Scientific American Supplement, No. 446, July 19, 1884
by
Various
Part 2 out of 3
Mr. Conrad Cooke said, "The first and most striking principle of Hughes'
microphone is a shaking and variable contact between the two parts
constituting the microphone." "The shaking and variable contact is
produced by the movable portion being effected by sound." "Under Hughes'
system, where gas carbon was used, the instruments could not possibly
work upon the principle of pressure." "I am satisfied that it is not
pressure in the sense of producing a change of resistance." "I do not
think pressure has anything to do with it."
Professor Blyth said: "The Hughes microphone depends essentially upon
the looseness or delicacy of contact." "I have heard articulate speech
with such an instrument without a diaphragm." "There is no doubt that to
a certain extent there must be a change in the number of points of
surface contact when the pencil is moved." "The action of the Hughes
microphone depends more or less upon the looseness or delicacy of the
contact and upon the changes in the number of points of surface contact
when the pencil is moved."
Mr. Oliver Heaviside, in _The Electrician_ of 10th February last,
writes: "There should be no jolting or scraping." "Contacts, though
light, should not be loose."
[Illustration: Fig. 2.]
A writer, who signs "W.E.H.," in _The Electrician_ of 24th February
last, says: "The variation of current arises from a variation of
conductivity between the electrodes, consequent upon the variation of
the closeness or pressure of contact;" and also, "there must be a
variation of pressure between the electrodes when the transmitter is in
action."
It seems, then, that some scientific men agree that variation of
pressure is required to produce action in a microphone, and some of them
admit that a microphone with loose contacts will transmit articulate
speech, while others deny it, and some admit that a jolting or shaking
motion of the parts of the microphone does not interfere with articulate
speech, while others say such motion would break the circuit, and cannot
be relied on.
I will now describe two microphones in which there is a shaking or
jolting motion, and loose contacts, and no variation of pressure of the
carbons against one another, and both of these microphones when used
with an induction coil and battery give most excellent articulation. One
of these microphones is made as follows: Two flat plates of carbon are
secured to a block of cork, insulated from each other; into a hole of
each carbon a pin of carbon fits loosely, projecting above the carbons;
another flat piece of carbon, having two holes in it, bridges over the
two lower carbons, being kept in its place by the pins of carbon which
fit loosely in the holes in it, the bottom carbons being connected with
the battery; a block of cork has a flat side of it cut out so as when
secured to the lower cork the carbons will not come in contact with it,
yet be close enough to it to keep the carbons from falling apart. The
cork covering the carbons forms a dome.
Any good telephone receiver when used in connection with this
microphone, reproduces articulate speech with remarkable distinctness,
especially hissing sounds, and with a loud and full tone.
A description of this microphone was published in _La Lumiere
Electrique_, of 15th April, 1882, and a drawing thereof on 29th April of
same year.
Another form of microphone is made as follows: Two blocks of gas carbon,
C, B, each about one and a half inches long and one inch square, having
each a circular hole one and a quarter inches deep and half inch in
diameter; these two blocks are embedded in a block of cork, C, about
one-quarter of an inch apart, these holes facing each other, each block
forming a terminal of the battery and induction coil; a pencil of
carbon, C, P, about three-eighths of an inch in diameter, and two inches
long, having a ring of ebonite, V, fixed around its center, is placed in
the holes of the two fixed blocks; the ebonite ring fitting loosely in
between the two blocks so as to prevent the pencil from touching the
bottom of the holes in the blocks. The space between the blocks is
closed with wax, W, to exclude the air, but not to touch the ring on the
pencil. A block of cork fitting close to the carbon blocks on all sides
is then firmly secured to the other block of cork. The microphone should
lie horizontally or at a slight angle.
This microphone produces in any good telephone perfect articulation in a
loud and full tone. In these microphones there is certainly "looseness
and delicacy of contact," and there is a "jolting or shaking motion,"
and it does not seem possible that there can be any "pressure of one
carbon against another."
I repeat the question I asked at the beginning of this communication,
and hope that it may elicit from you, or some of our scientific men, an
explanation of the theory of the action of this form of microphone.
W.C. BARNEY.
* * * * *
THE DEMBINSKI MICROPHONIC TELEPHONE TRANSMITTER.
This apparatus, which is shown by Figs. 1, 2, and 3, consists of a
wooden case, A, of oblong shape, closed by a lid fixed by hinges to the
top or one side of the case. The lid is actually a frame for holding a
piece of wire gauze, L L, through which the sound waves from the voice
can pass. In the case a flat shallow box, E F (or several boxes), is
placed, on the lid of which the carbon microphone, D C (Figs. 1 and 3),
which is of the ordinary construction, is placed. The box is of thin
wood, coated inside with petroleum lamp black, for the purpose of
increasing the resonance. It is secured in two lateral slides, fixed to
the case. The bottom of the box is pierced with two openings, resembling
those in a violin (Fig. 2). Lengthwise across the bottom are stretched a
series of brass spiral springs, G G G, which are tuned to a chromatic
scale. On the bottom of the case a similar series of springs, not shown,
are secured. The apparatus is provided with an induction coil, J, which
is connected to the microphone, battery, and telephone receiver (which
may be of any known description) in the usual manner.
[Illustration: Fig. 1.]
The inventors claim that the use of the vibrating springs give to the
transmitter an increased power over those at present in use. They state
that the instrument has given very satisfactory results between Ostende
and Arlon, a distance of 314 kilometers (about 200 miles). It does not
appear, however, that microphones of the ordinary Gower-Bell type, for
example, were tried in competition with the new invention, and in the
absence of such tests the mere fact that very satisfactory results were
obtained over a length of 200 miles proves very little. With reference
to a statement that whistling could be very clearly heard, we may remark
that experience has many times proved that the most indifferent form of
transmitter will almost always respond well and even powerfully to such
forms of vibration.--_Electrical Review_.
[Illustration: Fig. 2.]
[Illustration: Fig. 3.]
* * * * *
NEW GAS LIGHTERS.
We are going to make known to our readers two new styles of electric
lighters whose operation is sure and quick, and the use of which is just
as economical as that of those quasi-incombustible little pieces of wood
that we have been using for some years under the name of matches.
[Illustration: Fig. 1.--MODE OF USING THE GAS LIGHTER.]
The first of these is a portable apparatus designed for lighting gas
burners, and is based upon the calorific properties of the electric
spark produced by the induction bobbin. Its internal arrangement is such
as to permit of its being used with a pile of very limited power and
dimensions. The apparatus has the form of a rod of a length that may be
varied at will, according to the height of the burner to be lighted, and
which terminates at its lower part in an ebonite handle about 4
centimeters in width by 20 in length (Fig. 1). This handle is divided
into two parts, which are shown isolatedly in Fig. 2, and contains the
pile and bobbin. The arrangement of the pile, A, is kept secret, and all
that we can say of it is that zinc and chloride of silver are employed
as a depolarizer. It is hermetically closed, and carries at one of its
extremities a disk, B, and a brass ring, C, attached to its poles and
designed to establish a communication between the pile and bobbin when
the two parts of the apparatus are screwed together. To this end, two
elastic pieces, D and E, fit against B and C and establish a contact. It
is asserted that the pile is capable of being used 25,000 times before
it is necessary to recharge it. H is an ebonite tube that incloses and
protects the induction bobbin, K, whose induced wire communicates on the
one hand with the brass tube, L, and on the other with an insulated
central conductor, M, which terminates at a point very near the
extremity of the brass tube. The currents induced in this wire produce a
series of sparks between the tube, L, and the rod, M, which light the
gas when the extremity of the apparatus is placed in proximity with the
burner.
[Illustration: Fig. 2. MECHANISM OR THE INDUCTION SPARK GAS LIGHTER.]
The ingenious and new part of the system lies in the mode of exciting
the induced currents. When the extremity of the tube, L, is brought near
the gas burner that is to be lighted, it is only necessary to shove the
botton, F, from left to right in order to produce a _limited_ number of
sparks sufficient to effect the lighting. The motion of the button has
not for effect, as might be believed, the closing of the circuit of the
pile upon the inducting circuit of the bobbin. In fact in its normal
position, the vibrator is distant from its contact, and the closing of
the circuit would produce no action. The motion of F produces a
_mechanical_ motion of the spring of the vibrator, which latter acts for
a few instants and produces a certain number of contacts that give rise
to an equal number of sparks. Owing to this arrangement, the expenditure
of electric energy required by each lighting is limited; and, an another
hand, the vibrator, which would be incapable of operating if it had to
be set in motion by the direct current from the pile, can be actuated
_mechanically_. As the motion of the vibrator is derived from the hand
of the operator, and not from the pile, it will be comprehended that the
latter can, everything being equal, produce a larger number of lightings
than an ordinary bobbin and vibrator.
[Illustration: Fig. 3.--INCANDESCENT GAS LIGHTER.]
Dr. Naret's _Fiat Lux_ (Fig. 3) is simpler in its operation, and cheaper
of application, since it takes its current from the ordinary piles that
supply domestic call-bells. It consists essentially of a fine platinum
wire supported by a tilting device in connection with the two poles of a
pile composed of three Leclanche elements. Upon exerting a vertical
pressure on the button placed to the left of the apparatus, either
directly or by means of a cord, we at the same time turn the cock and
cause the platinum spiral to approach, and the latter then becomes
incandescent as a consequence of the closing of the circuit of the pile.
After the burner is lighted it is only necessary to leave the apparatus
to itself. The cock remains open, the spiral recedes from the burner,
the circuit opens anew, and the burner remains lighted until the gas is
turned off. This device, then, is particularly appropriate in all cases
where there is a pressing need of light, for a single maneuver suffices
to open the cock and effect a lighting of the burner.--_La Nature_.
* * * * *
DISTRIBUTION OF HEAT WHICH IS DEVELOPED BY FORGING.
On the 8th of June. 1874, Tresca presented to the French Academy some
considerations respecting the distribution of heat in forging a bar of
platinum, and stated the principal reasons which rendered that metal
especially suitable for the purpose. He subsequently experimented, in a
similar way, with other metals, and finally adopted Senarmont's method
for the study of conductibility. A steel or copper bar was carefully
polished on its lateral faces, and the polished portion covered with a
thin coat of wax. The bar thus prepared was placed under a ram, of known
weight, P, which was raised to a height, H, where it was automatically
released so as to expend upon the bar the whole quantity of work _T=PH,_
between the two equal faces of the ram and the anvil. A single shock
sufficed to melt the wax upon a certain zone and thus to limit, with
great sharpness, the part of the lateral faces which had been raised
during the shock to the temperature of melting wax. Generally the zone
of fusion imitates the area comprised between the two branches of an
equilateral hyperbola, but the fall can be so graduated as to restrict
this zone, which then takes other forms, somewhat different, but always
symmetrical. If A is the area of this zone, b the breadth of the bar, d
the density of the metal, c its capacity for heat, and t-t0 the excess
of the melting temperature of wax over the surrounding temperature, it
is evident that, if we consider A as the base of a horizontal prism
which is raised to the temperature t, the calorific effect may be
expressed by:
Ab x d x C(t-t0);
and on multiplying this quantity of heat by 425 we find, for the value
of its equivalent in work,
T' = 425 AbdC(t-t0).
On comparing T' to T we may consider the experiment as a mechanical
operation, having a minimum of:
T'/T = (425/PH)AbdC(t-t0).
After giving diagrams and tables to illustrate the geometrical
disposition of the areas of fusion, Tresca feels justified in concluding
that the development of heat depends upon the form of the faces and the
intensity of the shock; that the points of greatest heat correspond to
the points of greatest flow of the metal, and that this flow is really
the mechanical phenomenon which gives rise to the calorific phenomenon;
that for action sufficiently energetic and for bars of sufficient
dimensions, about 0.8 of the labor expended on the blow may be found
again in the heat; that the figures formed in the melted wax for shocks
of less intensity furnish a kind of diagram of the distribution of the
heat and of the deformation in the interior of the bar, but that the
calculation of the coefficient of efficiency does not yield satisfactory
results in the case of moderate blows.--_Comptes Rendus_.
* * * * *
TIN IN CANNED FOODS.
[Footnote: Read at an evening meeting of the Pharmaceutical Society,
March 5, 1884.]
By PROFESSOR ATTFIELD, F.R.S., ETC.
From time to time, during the past twelve years, paragraphs have
appeared in newspapers and other periodicals tending in effect to warn
the public at least against the indiscriminate use of canned foods. And
whenever there has been any foundation in fact for such cautions, it has
commonly rested on the alleged presence and harmfulness of tin in the
food. At the worst, the amount of tin present has been absurdly small,
affording an opportunity for one literary representative of medicine to
state that before a man could be seriously affected by the tin, even if
it occurred in the form of a compound of the metal, he would have to
consume at a meal ten pounds of the food containing the largest amount
of tin ever detected.
But the greatest proportions of tin thus referred to are, according to
my experiments, far beyond those ever likely to be actually present in
the food itself in the form of a compound of tin; present, that is to
say, on account of the action of the fluids or juices of the food on the
tin of the can. Such action and such consequent solution of the tin, and
consequent admixture of a possibly assimilable compound of tin with the
food, in my opinion never occurs to an extent which in relation to
health has any significance whatever. The occurrence of tin, not as a
compound, but as the metal itself, is, if possible, still less
important.
During the last fifteen years I have frequently examined canned foods,
not only with respect to the food itself as food, and to the process of
canning, but with regard to the relation of the food to, or the
influence if any of the metal of, the can itself. So lately as within
the past two or three months I have examined sixteen varieties of canned
food for metals, with the following results:
Decimal parts of
a grain of tin
(or other foreign
metal) present in
Name of article a quarter of a lb.
examined.
Salmon none.
Lobsters none.
Oysters 0.004
Sardines none.
Lobster paste none.
Salmon paste none.
Bloater paste 0.002
Potted beef none.
Potted tongue none.
Potted "Strasbourg" none.
Potted ham 0.002
Luncheon tongue 0.003
Apricots 0.007
Pears 0.003
Tomatoes 0.007
Peaches 0.004
These proportions of metal are, I say, undeserving of serious notice. I
question whether they represent more than the amounts of tin we
periodically wear off tin saucepans in preparing food--a month ago I
found a trace of tin in water which had been boiled in a tin kettle--or
the silver we wear off our forks and spoons. There can be little doubt
that we annually pass through our systems a sensible amount of such
metals, metallic compounds, and other substances that do not come under
the denomination of food; but there is no evidence that they ever did or
are ever likely to do harm or occasion us the slightest inconvenience.
Harm is far more likely to come to us from noxious gases in the air we
breathe than from foreign substances in the food we eat.
But whence come the much less minute amounts of tin--still harmless, be
it remembered--which have been stated to be occasionally present in
canned foods? They come from the minute particles of metal chipped off
from the tin sheets in the operations of cutting, bending, or hammering
the parts of the can, or possibly melted off in the operations necessary
for the soldering together of the joints of the can. Some may, perhaps,
be cut, off by the knife in opening a can. At all events I not
unfrequently find such minute particles of metal on carefully washing
the external surfaces of a mass of meat just removed from a can, or on
otherwise properly treating canned food with the object of detecting
such particles. The published processes for the detection of tin in
canned food will not reveal more than the amounts stated in the table,
or about those amounts; that is to say, a few thousandths or perhaps two
or three hundredths of a grain, if this precaution be adopted. If such
care be not observed, the less minute amounts may be found. I did not
detect any metallic particles in the twelve samples of canned food just
mentioned, but during the past few years I have occasionally found small
pieces of metal, perhaps amounting in some of the cases to a few tenths
of a grain per pound. Now and then small shot-like pieces of tin, or
possibly solder, may be met with; but no one has ever found, to my
knowledge, such a quantity of actual metallic tin, tinned iron, or
solder as, from the point of view of health, can have any significance
whatever.
The largest amount of tin I ever detected in actual solution in food was
in some canned soup, containing a good deal of lemon juice. It amounted
to only three-hundredths of a grain in a half pint of the soup as sent
to table. Now, Christison says that quantities of 18 to 44 grains of the
very soluble chloride of tin were required to kill dogs in from one to
four days. Orfila says that several persons on one occasion dressed
their dinner with chloride of tin, mistaking it for salt. One person
would thus take not less than 20 to 30 grains of this soluble compound
of tin. Yet only a little gastric and bowel disturbance followed, and
from this all recovered in a few days. Pereira says that the dose of
chloride of tin as an antispasmodic and stimulant is from 1/16 to 1/2 a
grain repeated two or three times daily. Probably no article of canned
food, not even the most acid fruit, if in a condition in which it can be
eaten, has ever contained, in an ordinary table portion, as much of a
soluble salt of tin as would amount to a harmless or useful medicinal
dose.
Metallic particles of tin are without any effect on man. A thousand
times the quantity ever found in a can of tinned food would do no harm.
Food as acid as say ordinary pickles would dissolve tin. Some
manufacturers once proposed using tin stoppers to their bottles of
pickles. But the tin was slowly dissolved by the acid of the vinegar.
These pickles, however, had a distinctly nasty "metallic" flavor. The
idea was abandoned. Probably any article of food containing enough tin
to disagree with the system would be too nasty to eat. Purchasers of
food may rest assured that the action taken by this firm would be that
usually followed. It is not to the interest of manufacturers or other
venders to offend the senses of purchasers, still less to do them actual
harm, even if no higher motive comes into force.
In the early days of canning, it is just possible that the use of
"spirits of salt" in soldering may have resulted in the presence of a
little stannous, plumbous, or other chloride in canned food; but such a
fault would soon be detected and corrected, and as a matter of fact,
resin-soldering is to my knowledge more generally employed--indeed, for
anything I know to the contrary, is exclusively employed--in canning
food. Any resin that trained access would be perfectly harmless. It is
just possible, also, that formerly the tin itself may have contained
lead, but I have not found any lead in the sheet tin used for canning of
late years.
In conclusion: 1. I have never been able to satisfy myself that a can of
ordinary tinned food contains even a useful medicinal dose of such a
true soluble _compound_ of tin as is likely to have any effect on man.
2. As for the metal itself, that is the filings or actual metallic
particles or fragments, one ounce is a common dose as a vermifuge;
harmless even in that quantity to man, and not always so harmful as
could be desired to the parasites for whose disestablishment it is
administered. One ounce might be contained in about four hundredweight
of canned food. 3. If a possibly harmful quantity of a soluble compound,
of tin be placed in a portion of canned food, the latter will be so
nasty and so unlike any ordinary nasty flavor, so "metallic," in fact,
that no sane person will eat it. 4. Respecting the globules of solder
(lead and tin) that are occasionally met with in canned food, I believe
most persons detect them in the mouth and remove them, as they would
shots in game. But if swallowed, they do no harm. Pereira says that
metallic lead is probably inert, and that nearly a quarter of a pound
has been administered to a dog without any obvious effects. He goes on
to say that as it becomes oxidized it occasionally acquires activity,
quoting Paulini's statement that colic was produced in a patient who had
swallowed a leaden bullet. To allay alarm in the minds of those who fear
they might swallow pellets of solder, I may add that Pereira cites
Proust for the assurance that an alloy of tin and lead is less easily
oxidized than pure lead. 5. Unsoundness in meat does not appear to
promote the corrosion or solution of tin. I have kept salmon in cans
till it was putrid, testing it occasionally for tin. No trace of tin was
detected. Nevertheless, food should not be allowed to remain for a few
days, or even hours, in saucepans, metal baking pans, or opened tins or
cans, otherwise it _may_ taste metallic. 6. Unsound food, canned or
uncanned, may, of course, injure health, and where canned food really
has done harm, the harm has in all probability been due to the food and
not to the can. 7. What has been termed idiosyncrasy must also be borne
in mind. I know a man to whom oatmeal is a poison. Some people cannot
eat lobsters, either fresh or tinned. Serious results have followed the
eating of not only oatmeal or shell fish, but salmon and mutton;
_hydrate_ (misreported _nitrate_) of tin being gratuitously suggested as
being contained in the salmon in one case. Possibly there were cases of
idiosyncrasy in the eater, possibly the food was unsound, possibly other
causes altogether led to the results, but certainly, to my mind, the tin
had nothing whatever to do with the matter.
In my opinion, given after well weighing all evidence hitherto
forthcoming, the public have not the faintest cause for alarm respecting
the occurrence of tin, lead, or any other metal in canned foods.--_Phar.
Jour, and Trans., March 8, 1884, p. 719_.
[In reference to Prof. Attfield's statement contained in the closing
paragraph, we remark: It is well known that mercury is an ingredient of
the solder used in some canning concerns, as it makes an easier melting
and flowing solder. In THE SCIENTIFIC AMERICAN for May 27, 1876, in a
report of the proceedings of the New York Academy of Science, will be
seen the statement of Prof. Falke, who found metallic mercury in a can
of preserved corn beef, together with a considerable quantity of
albuminate of mercury.--EDS. S.A.]
* * * * *
VILLA AT DORKING.
The house shown in the illustration was lately erected from the designs
of Mr. Charles Bell, F.R.I.B.A. Although sufficiently commodious, the
cost has been only about 1,050_l_.--_The Architect_.
[Illustration: SUGGESTIONS IN ARCHTECTURE.--AN ENGLISH COTTAGE. COST,
$5,250.]
* * * * *
Valerianate of cerium in the vomiting of pregnancy is recommended by Dr.
Blondeau in a communication to the _Societe de Therapeutique_. He gives
it in doses of 10 centigrammes three times a day.--_Medical Record_.
* * * * *
[Illustration: ARM CHAIR IN THE LOUVRE COLLECTION, PARIS; FLENISH
RENAISSANCE.--_From The Workshop._]
* * * * *
TECHNICAL EDUCATION IN AMERICA.
If there is one point more than another in which the exuberant youth and
vitality of the American nation is visible it is in that of education,
the provision for which is on a most generous scale, carried out with a
determination at which the older countries of the Eastern Hemisphere
have only arrived by slow degrees and painful experience. Of course the
Americans, being young, and having come to the fore, so to speak,
full-fledged, have been able to profit by the lessons which they have
derived from their neighbors--though it is none the less to their credit
that they have profited so well and so quickly. Technical and industrial
education has received a more general recognition, and been developed
more rapidly, than the general education of the country, partly for the
reason that there is no uniform system of the latter throughout the
States, but that each individual State and Territory does that which is
right in its own eyes. The principal reason, however, is that to possess
the knowledge, how to work is the first creed of the American, who
considers that the right to obtain that knowledge is the birthright of
every citizen, and especially when the manual labor has to be
supplemented by a vigorous use of brains. The Americans as a rule do not
like heavy or coarse manual labor, thinking it beneath them; and,
indeed, when they can get Irish and Chinese to do it for them, perhaps
they are not far wrong. But the idea of idleness and loafing is very far
from the spirit of the country, and this is why we see the necessity for
industrial education so vigorously recognized, both as a national duty,
and by private individuals or communities of individuals.
From whatever source it is provided, technical education in the United
States comes mainly within the scope of two classes of institutions,
viz., agricultural and mechanical colleges; although the two are, as
often as not, combined under one establishment, and particularly it
forms the subject of a national grant. Indeed, it may be said that the
scope of industrial education embraces three classes: the farmer, the
mechanic, and the housekeeper; and in the far West we find that
provision is made for the education of these three classes in the same
schools, it being an accepted idea in the newer States that man and
woman (the housekeeper) are coworkers, and are, therefore, entitled to
equal and similar educational privileges. On the other hand, in the more
conservative East and South, we find that the sexes are educated
distinct from each other. In the East, there is generally, also, a
separation of subjects. In Massachusetts, for instance, the colleges of
agriculture and mechanics are separate affairs, the students being
taught in different institutions, viz., the agricultural college and the
institute of technology. In Missouri the separation is less defined, the
School of Mines and Metallurgy being the, only part that is distinct
from the other departments of the University.
One of the chief reasons for the necessity for hastening the extension
of technical education in America was the almost entire disappearance of
the apprenticeship system, which, in itself, is mainly due to the
subdivision of labor so prevalent in the manufacture of everything, from
pins to locomotives. The increased use of machinery, the character of
which is such as often to put an end to small enterprises, has promoted
this subdivision by accumulating workmen in large groups. The beginner,
confining himself to one department, is soon able to earn wages, and so
he usually continues as he begins. Mr. C.B. Stetson has written on this
subject with great force and earnestness, and it will not be amiss to
quote a sentence as to the advantages enjoyed by the technically
workman. He says that "it is the rude or dexterous workman, rather than
the really skilled one, who is supplanted by machinery. Skilled labor
requires thinking; but a machine never thinks, never judges, never
discriminates. Though its employment does, indeed, enable rude laborers
to do many things now which formerly could only be done by dexterous
workmen, it is clear that its use has decidedly increased the relative
demand for skilled labor as compared with unskilled, and there is
abundant room for an additional increase, if it is true, as declared by
the most eminent authority, that the power now expended can be readily
made to yield three or four times its present results, and ultimately
ten or twenty times, when masters and workmen can be had with sufficient
intelligence and skill for the direction and manipulation of the tools
and machinery that would be invented."
The establishment of colleges and universities by the aid of national
grants has depended very much for their character upon the industrial
tendencies of the respective States, it being understood that the land
grants have principally been given to those of the newer States and
Territories which required development, although some of the
institutions of the older States on the Atlantic seaboard have also been
recipients of the same fund, which in itself only dates from an act of
Congress in 1862. In California and Missouri, both States abounding in
mineral resources, there are courses in mining and metallurgy provided
in the institutions receiving national aid. In the great grain-producing
sections of the Mississippi Valley the colleges are principally devoted
to agriculture, whereas the characteristic feature of the Iowa and
Kansas schools is the prominence given to industries.
We need not devote attention to the aims and arrangements of the
agricultural colleges proper, but will pass at once to those which deal
with the mechanical arts, dealing first of all with those that are
assisted by the national land grant. Taking them alphabetically, we have
first the State Agricultural College of Colorado, in the mechanical and
drawing department of which shops for bench work in wood and iron and
for forging have been recently erected, this institution being one of
the newest in America. In the Illinois Industrial University the student
of mechanical engineering receives practice in five shops devoted to
pattern-making, blacksmithing, moulding and founding, benchwork for
iron, and machine tool-work for iron. In the first shop the practice
consists of planing, chiseling, turning, and the preparation of patterns
for casting. The ordinary blacksmithing operations take place in the
second shop, and those of casting in the third. In the fourth there is,
first of all, a course of freehand benchwork, and afterward the fitting
of parts is undertaken. In the fifth shop all the fundamental operations
on iron by machinery are practiced, the actual work being carefully
outlined beforehand by drawings. This department of the University
consists, in point of fact, of three separate schools, destined to
qualify the student for every kind of engineering--mining, railway,
mechanical, and architectural. In addition to the shops and machine
rooms, there are well furnished cabinets of geological and mineralogical
specimens, chemical laboratories for assaying and metallurgy, stamp
mill, furnaces, etc., and, in fact, every known vehicle for practical
instruction. The school of architecture prepares students for the
building profession. Among the subjects in this branch are office work
and shop practice, constructing joints in carpentry and joinery, cabinet
making and turning, together with modeling in clay. The courses in
mathematics, mechanics and physics are the same as those in the
engineering school; but the technical studies embrace drawing from
casts, wood, stone, brick, and iron construction, turners' work,
slating, plastering, painting, and plumbing, architectural drawing and
designing, the history and aesthetics of architecture, estimates,
agreements specification, heating, lighting, draining, and ventilation.
The student's work from scale drawing occupies three terms, carpentry
and joinery being taught in the first year, turning and cabinet making
in the second, metal and stone work in the third. A more condensed
course, known as the builder's course, is given to those who can only
stop one year. The machine shop has a steam engine of 16 horse power,
two engines and three plain lathes, a planer, a large drill press, a
pattern shop, a blacksmith's shop, all of the machinery having been
built on the spot. The carpenter's shop is likewise supplied with
necessary machine tools, such as saws, planers, tenoning machine,
whittlers, etc., the power being furnished by the machine shop. At the
date of the last University report, there were 41 students in the
courses of mechanical engineering, 41 in those of civil engineering, 3
in mining engineering, and 14 in architecture. Tuition is free in all
the University classes, though each student has to pay a matriculation
fee of $10, and the incidental expenses amount to about $23 annually. He
is charged for material used or apparatus broken, but not for the
ordinary wear and tear of instruments. It should be mentioned that the
endowment of the Illinois Industrial University is from scrip received
from the Government for 480,000 acres of land, of which 454,460 have
been sold for $319,178. The real estate of the University, partly made
up by donations and partly by appropriations made in successive sessions
by the State of Illinois, is estimated at $450,000.
The Purdue University in Indiana, named after its founder, who gave
$150,000, which was supplemented by another $50,000 from the State and a
bond grant of 390,000 acres, also provides a very complete mechanical
course, with shop instruction, divided as follows:
Bench working in wood for 12 weeks, or 120 hours.
Wood-turning " 4 " " 40 "
Pattern-making " 12 " " 120 "
Vise-work in iron " 10 " " 100 "
Forging in iron and steel " 18 " " 180 "
Machine tool-work in iron " 20 " " 200 "
The course in carpentry and joinery embraces: 1. Exercising in sawing
and planing to dimensions. 2 Application, or box nailed together. 3
Mortise and tenon joints; a plain mortise and tenon; an open dovetailed
mortise and tenon (dovetailed halving); a dovetailed keyed mortise and
tenon. 4. Splices. 5. Common dovetailing. 6. Lap dovetailing and
rabbeting. 7. Blind or secret dovetail. 8. Miter-box. 9. Carpenter's
trestle. 10. Panel door. 11. Roof truss. 12. Section of king-post truss
roof. 13. Drawing model.
The course in wood turning includes: 1. Elementary principles: first,
straight turning; second, cutting in; third, convex curves with the
chisel; fourth, compound curves formed with the gouge. 2. File and
chisel handles. 3. Mallets. 4. Picture frames (chuck work). 5. Card
receiver (chuck work). 6. Watch safe (chuck work). 7. Ball.
In the pattern-making course the student is supposed to have some skill
in bench and lathe work, which will be increased; the direct object
being to teach what forms of pattern are in general necessary, and how
they must be constructed in order to get a perfect mould from them. The
character of the work differs each year. For instance, for the last
year, besides simpler patterns easily drawn from the sand, such as
glands, ball-cranks, etc., there were a series of flanged pipe-joints
for 21/2 in. pipes, including the necessary core boxes; also pulley
patterns from 6 in. to 10 in. diameter, built in segments for strength,
and to prevent warping and shrinkage; and, lastly, a complete set of
patterns for a three horse-power horizontal steam engine, all made from
drawings of the finished piece. In the vise work in iron, the chief
requirements are these: 1, given a block of cast iron 4 in. by 2 in. by
11/2 in. in thickness, to reduce the thickness 1/4 in. by chipping, and then
finishing with the file; 2, to file a round hole square; 3, to file a
round hole into elliptical; 4, given a 3 in. cube of wrought iron, to
cut a spline 3 in. by 3/8 in. by 1/4 in., and second, when the under side
is a one half round hollow--these two cuts involve the use of the cope
chisel and the round nose chisel, and are examples of very difficult
chipping; 5, round tiling or hand-vise work; 6, scraping; 7, special
examples of fitting. In the forging classes are elementary processes,
driving, bending, and upsetting; courses in welding; miscellaneous
forging; steel forging, including hardening and tempering in all its
details.
It is worth mentioning that in the industrial art school of the Purdue
University there were 13 of the fair sex as students, besides one in the
chemical school, and two going through the mechanical courses just
detailed, showing that the scope of woman's industry is less limited in
America than in England. The Iowa State Agricultural College has also
two departments of mechanical and civil engineering, the former
including a special course of architecture. The workshop practice, which
occupies three forenoons of 21/2 hours each per week, is, however, of more
general character, and is not pursued with such a regard to any special
calling as in the case of the Purdue University.
The Kansas State Agricultural College has a course of carpentry, though
designed rather more to meet the everyday necessities of a farmer's
life. In fact, all the students are obliged to attend these classes, and
take the same first lessons in sawing, planing, lumber dressing, making
mortises, tenons, and joints, and in general use of tools--just the kind
of instruction that every English lad should have before he is shipped
off to the Colonies. This farmer's course in the Kansas College provides
for a general training in mechanical handiwork, but facilities are given
also to those who wish to follow out the trade, and special instruction
is provided in the whole range of work, from framing to stair-building,
as also in iron work, such as ordinary forging, filing, tempering, etc.
Of the students attending this college, 75 percent, are from farmers'
homes, and the majority of the remainder from the families of mechanics
and tradesmen.
The State College of Maine provides courses for both civil and
mechanical engineers, and has two shops equipped according to the
Russian system. Forge and vise work are taught in them, though it is not
the object of the college so much to teach the details of any one trade
as to qualify students by general knowledge to undertake any of them
afterward. A much more complete and thorough technical education is
given in the Massachusetts Institute of Technology at Boston, where
there are distinct classes for civil, mechanical, mining, geological,
and architectural engineering. The following are the particulars of the
instruction in the architectural branch, which commences in the
student's second year, with Greek, Roman, and Mediaeval architectural
history, the Orders and their applications, drawing, sketching, and
tracing, analytic geometry, differential calculus, physics, descriptive
geometry, botany, and physical geography. In the third year the course
is extended to the theory of decoration, color, form, and proportion;
conventionalism, symbolism, the decorative arts, stained glass, fresco
painting, tiles, terra-cotta, original designs, specifications, integral
calculus, strength of materials, dynamics, bridges and roofs,
stereotomy. In the fourth year the student is turned out a finished
architect, after a course of the history of ornament, the theory of
architecture, stability of structure, flow of gases, shopwork
(carpentry), etc.
The number of students in this very comprehensive Institute of
Technology was, by the latest report, 390, of whom 138 were undergoing
special courses, 39 were in the schools of mechanical art, and 49 in the
Lowell School of Practical Design. Tuition is charged at the rate of 200
dols. for the institute proper, and 150 dols. for the mechanical
schools, the average expenses per student being about 254 dols. There
are 10 free scholarships, of which two are given for mechanical art. The
Lowell School has been established by the trustee of the Lowell
Institute to afford free technical education, under the auspices of the
Institute of Technology, to both sexes--a large number of young women
availing themselves of it in connection with their factory work at
Lowell. The courses include practical designs for manufactures, and the
art of making patterns for prints, delaines, silks, paperhangings,
carpets, oilcloth, etc., and the school is amply provided with pattern
looms. Indeed, the whole of the appliances for practical teaching at the
Institute are on such a complete scale that at the risk of being a
little tedious it is as well to enumerate them. They comprise
laboratories devoted to chemistry, mineralogy, metallurgy, and
industrial chemistry; there are also microscopic, spectroscopic, and
organic laboratories. In other branches there are laboratories and
museums of steam engineering, mining, and metallurgy, biology and
architecture, together with an observatory, much used in connection with
geodesy and practical astronomy. The steam engineering laboratory
provides practice in testing, adjusting, and managing steam machinery.
The appliances in connection with mining and metallurgy include a
five-stamp battery, Blake crusher, automatic machine jigs, an engine
pulverizer, a Root and a Sturtevant blower, with blast reverberating,
wasting, cupellation, and fusion furnaces, and all other means for
reducing ores. The architectural museum contains many thousand casts,
models, photographs, and drawings. The shops for handwork are large and
well arranged, and include a vise-shop, forge shop, machine, tool, and
lathe shops, foundry, rooms for pattern making, weaving, and other
industrial institutions. The vise-shop contains four heavy benches, with
32 vises attached, giving a capacity for teaching 128 students the
course every ten weeks, or 640 in a year of fifty weeks. The forge-shop
has eight forges. The foundry has 16 moulding benches, an oven for core
baking, and a blast furnace of one-half ton capacity. The
pattern-weaving room is provided with five looms, one of them in
20-harness, and 4-shuttle looms, and another an improved Jacquard
pattern loom. It may safely be said that there is nor an establishment
in the world better equipped for industrial and technical education than
this Institute of Massachusetts.--_London Building News_.
* * * * *
IVORY GETTING SCARCE.--The stock of ivory in London is estimated at
about forty tons in dealers' private warehouses, whereas formerly they
usually held about one hundred tons. One fourth of all imported into
England goes to the Sheffield cutlers. No really satisfactory substitute
for ivory has been found, and millions await the discoverer of one. The
existing substitutes will not take the needed polish.
* * * * *
THE ANAESTHETICS OF JUGGLERS.
Fakirs are religious mendicants who, for the purpose of exciting the
charity of the public, assume positions in which it would seem
impossible that they could remain, submit themselves to fearful
tortures, or else, by their mode of living, their abstinence, and their
indifference to inclement weather and to external things, try to make
believe that, owing to their sanctity, they are of a species superior to
that of common mortals.
In the Indies, these fakirs visit all the great markets, all religious
fetes, and usually all kinds of assemblages, in order to exhibit,
themselves. If one of them exhibits some new peculiarity, some curious
deformity, a strange posture, or, finally, any physiological curiosity
whatever that surpasses those of his confreres, he becomes the
attraction of the fete, and the crowd surrounds him, and small coin and
rupees begin to fall into his bowl.
Fakirs, like all persons who voluntarily torture themselves, are curious
examples of the modifications that will, patience, and, so to speak,
"art" can introduce into human nature, and into the sensitiveness and
functions of the organs. If these latter are capable of being improved,
of having their functions developed and of acquiring more strength (as,
for example, the muscles of boxers, the breast of foot racers, the voice
of singers, etc.), these same organs, on the contrary, can be atrophied
or modified, and their functions be changed in nature. It is in such
degradation and such degeneration of human nature that fakirs excel, and
it is from such a point of view that they are worth studying.
We may, so to speak, class these individuals according to the grades of
punishments that they inflict upon themselves, or according to the
deformities that they have caused themselves to undergo. But, as we have
already said, the number of both of these is extremely varied, each
fakir striving in this respect to eclipse his fellows. It is only
necessary to open a book of Indian travel to find descriptions of fakirs
in abundance; and such descriptions might seem exaggerated or unlikely
were they not so concordant. The following are a few examples:
_Immovable fakirs_.--The number of these is large. They remain immovable
in the spot they have selected, and that too for an exceedingly long
period of time. An example of one of these is cited who remained
standing for twelve years, his arms crossed upon his breast, without
moving and without lying or sitting down. In such cases charitable
persons always take it upon themselves to prevent the fakir from dying
of starvation. Some remain sitting, immovable, and apparently lifeless,
while others, who lie stretched out upon the ground, look like corpses.
It may be easily imagined what a state one of these beings is in after a
few months or years of immobility. He is extremely lean, his limbs are
atrophied, his body is black with filth and dust, his hair is long and
dishevelled, his beard is shaggy, his finger and toe nails have become
genuine claws, and his aspect is frightful. This, however, is a
character common to all fakirs.
We may likewise class among the immovables those fakirs who cause
themselves to be interred up to the neck, and who remain thus with their
head sticking out of the ground either during the entire time the fair
or fete lasts or for months and years.
_Anchylotic Fakirs_.--The number of fakirs who continue to hold one or
both arms outstretched is very large in India. The following description
of one of them is given by a traveler: "He was a goussain--a religious
mendicant--who had dishevelled hair and beard, and horrible tattooings
upon his face, and, what was most hideous, was his left arm, which,
withered and anchylosed, stuck up perpendicularly from the shoulder. His
closed hand, surrounded by straps, had been traversed by the nails,
which, continuing to grow, had bent like claws on the other side.
Finally, the hollow of this hand, which was filled with earth, served as
a pot for a small sacred myrtle."
Other fakirs hold their two arms above their head, the hands crossed,
and remain perpetually in such a position. Others again have one or both
arms extended. Some hang by their feet from the limb of a tree by means
of a cord, and remain head downward for days at a time, with their face
uncongested and their voice clear, counting their beads and mumbling
prayers.
One of the most remarkable peculiarities of fakirs is the faculty that
certain of them possess of remaining entirely buried in vaults and
boxes, and inclosed in bags, etc., for weeks and months, and, although
there is a certain deceit as regards the length of their absolute
abstinence, it nevertheless seems to be a demonstrated fact that, after
undergoing a peculiar treatment, they became plunged into a sort of
lethargy that allows them to remain for several days or weeks without
taking food. Certain fakirs that have been interred under such
conditions have, it appears, passed ten months or a year in their grave.
_Tortured Fakirs_.--Fakirs that submit themselves to tortures are very
numerous. Some of them perform exercises analogous to those of the
Aissaoua. Mr. Rousselet, in his voyage to the Indies, had an opportunity
of seeing some of these at Bhopal, and the following is the picturesque
description that he gives of them: "I remarked some groups of religious
mendicants of a frightfully sinister character. They were Jogins, who,
stark naked and with dishevelled hair, were walking about, shouting, and
dancing a sort of weird dance. In the midst of their contortions they
brandished long, sharp poniards, of a special form, provided with steel
chains. From time to time, one of these hallucinated creatures would
drive the poniard into his body (principally into the sides of his
chest), into his arms, and into his legs, and would only desist when, in
order to calm his apparent fury, the idlers who were surrounding him
threw a sufficient number of pennies to him."
At the time of the feast of the Juggernaut one sees, or rather one _did_
see before the English somewhat humanized this ceremony, certain fakirs
suspended by their flesh from iron hooks placed along the sides of the
god's car. Others had their priests insert under their shoulder blades
two hooks, that were afterward fixed to a long pole capable of pivoting
upon a post. The fakirs were thus raised about thirty feet above ground,
and while being made to spin around very rapidly, smilingly threw
flowers to the faithful. Others, again, rolled over mattresses garnished
with nails, lance-points, poniards, and sabers, and naturally got up
bathed in blood. A large number cause 120 gashes (the sacred number) to
be made in their back and breast in honor of their god. Some pierce
their tongue with a long and narrow poniard, and remain thus exposed to
the admiration of the faithful. Finally, many of them are content to
pass points of iron or rods made of reed through folds in their skin. It
will be seen from this that fakirs are ingenious in their modes of
exciting the compassion and charity of the faithful.
Elsewhere, among a large number of savage tribes and half-civilized
peoples, we find aspirants to the priesthood of the fetiches undergoing,
under the direction of the members of the religious caste that they
desired to enter, ordeals that are extremely painful. Now, it has been
remarked for a long time that, among the neophytes, although all are
prepared by the same hands, some undergo these ordeals without
manifesting any suffering, while others cannot stand the pain, and so
run away with fright. It has been concluded from this that the object of
such ordeals is to permit the caste to make a selection from among their
recruits, and that, too, by means of anesthetics administered to the
chosen neophytes.
In France, during the last two centuries, when torturing the accused was
in vogue, some individuals were found to be insensible to the most
fearful tortures, and some even, who were plunged into a species of
somnolence or stupefaction, slept in the hands of the executioner.
What are the processes that permit of such results being reached?
Evidently, we cannot know them all. A certain number are caste, sect, or
family secrets. Many are known, however, at least in a general way. The
processes naturally vary, according to the object to be attained. Some
seem to consist only in an effort of the will. Thus, those fakirs who
remain immovable have no need of any special preparation to reach such a
result, and the same is the case with those who are interred up to the
neck, the will alone sufficing. Fakirs probably pass through the same
phases that invalids do who are forced to keep perfectly quiet through a
fracture or dislocation. During the first days the organism revolts
against such inaction, the constraint is great, the muscles contract by
starts, and then the patient gets used to it; the constraint becomes
less and less, the revolt of the muscles becomes less frequent, and the
patient becomes reconciled to his immobility. It is probable that after
passing several months or years in a state of immobility fakirs no
longer experience any desire to change their position, and even did they
so desire, it would be impossible owing to the atrophy of their muscles
and the anchylosis of their joints.
Those fakirs who remain with one or several limbs immovable and in an
abnormal position have to undergo a sort of preparation, a special
treatment; they have to enter and remain two or three mouths in a sort
of cage or frame of bamboo, the object of which is to keep the limb that
is to be immobilized in the position that it is to preserve. This
treatment, which is identical with the one employed by surgeons for
curing affections of the joints, has the effect of soldering or
anchylosing the articulation. When such a result is reached, the fakir
remains, in spite of himself and without fatigue, with outstretched
arms, and, in order to cause them to drop, he would have to undergo a
surgical operation.
As for those voluntary tortures that cause an effusion of blood, the
insensibility of those who are the victims of it is explainable when we
reflect that _India_ is _the_ country _par excellence_ of anaesthetic
plants. It produces, notably, Indian hemp and poppy, the first of which
yields hashish and the other opium. Now it is owing to these two
narcotics, taken in a proper dose, either alone or combined according to
a formula known to Hindoo fakirs and jugglers, but ignored by the lower
class, that the former are able to become absolutely insensible
themselves or make their adepts so.
[Illustration: INDIAN FAKIRS IN VARIOUS POSITIONS.]
There is, especially, a liquor known in the Indian pharmacopoeia under
the name of _bang_, that produces an exciting intoxication accompanied
with complete insensibility. Now the active part of bang consists of a
mixture of opium and hashish. It was an analogous liquor that the
Brahmins made Indian widows take before leading them to the funeral
pile. This liquor removed from the victims not only all consciousness of
the act that they were accomplishing, but also rendered them insensible
to the flames. Moreover, the dose of the anaesthetic was such that if, by
accident, the widow had escaped from the pile (something that more than
once happened, thanks to English protection), she would have died
through poisoning. Some travelers in Africa speak of an herb called
_rasch_, which is the base of anaesthetic preparations employed by
certain Arabian jugglers and sorcerers.
It was hashish that the Old Man of the Mountain, the chief of the sect
of Assassins, had recourse to for intoxicating his adepts, and it was,
it is thought, by the use of a virulent solanaceous plant--henbane,
thornapple, or belladonna--that he succeeded in rendering them
insensible. We have unfortunately lost the recipe for certain
anaesthetics that were known in ancient times, some of which, such as the
_Memphis stone_, appear to have been used in surgical operations. We are
also ignorant of what the wine of myrrh was that is spoken of in the
Bible.
We are likewise ignorant of the composition of the anaesthetic soap, the
use of which became so general in the 15th and 16th centuries that,
according to Taboureau, it was difficult to torture persons who were
accused. The stupefying recipe was known to all jailers, who, for a
consideration, communicated it to prisoners. It was this use of
anaesthetics that gave rise to the rule of jurisprudence according to
which partial or general insensibility was regarded as a certain sign of
sorcery. We may cite a certain number of preparations, which vary
according to the country, and to which is attributed the properly of
giving courage and rendering persons insensible to wounds inflicted by
the enemy. In most cases alcohol forms the base of such beverages,
although the _maslach_ that Turkish soldiers drink just before a battle
contains none of it, on account of a religious precept. It consists of
different plant-juices, and contains, especially, a little opium.
Cossacks and Tartars, just before battle, take a fermented beverage in
which has been infused a species of toadstool (_Agaricus muscarius_),
and which renders them courageous to a high degree.
As well known, the old soldiers of the First Empire taught the young
conscripts that in order to have courage and not feel the blows of the
enemy, it was only necessary to drink a glass of brandy into which
gunpowder had been poured.--_La Nature_.
* * * * *
[SCHOOL OF MINES QUARTERLY.]
THE DEPOSITION OF ORES.
By J.S. NEWBERRY.
MINERAL VEINS.
In the _Quarterly_ for March, 1880, a paper was published on "The Origin
and Classification of Ore Deposits," which treated, among other things,
of mineral veins. These were grouped in three categories, namely: 1.
Gash Veins; 2. Segregated Veins; 3. Fissure Veins; and were defined as
follows:
_Gash Veins_.--Ore deposits confined to a single bed or formation of
_limestone_, of which the joints, and sometimes planes of bedding,
enlarged by the solvent power of atmospheric water carrying carbonic
acid, and forming crevices, galleries, or caves, are lined or filled
with ore leached from the surrounding rock, e.g., the lead deposits of
the Upper Mississippi and Missouri.
_Segregated Veins_.--Sheets of quartzose matter, chiefly lenticular and
conforming to the bedding of the inclosing rocks, but sometimes filling
irregular fractures across such bedding, found only in metamorphic
rocks, limited in extent laterally and vertically, and consisting of
material indigenous to the strata in which they occur, separated in the
process of metamorphism, e.g., quartz ledges carrying gold, copper, iron
pyrites, etc., in the Alleghany Mountains, New England, Canada, etc.
_Fissure Veins_.--Sheets of metalliferous matter filling fissures caused
by subterranean force, usually in the planes of faults, and formed by
the deposit of various minerals brought from a lower level by water,
which under pressure and at a high temperature, having great solvent
power, had become loaded with matters leached from different rocks, and
deposited them in the channels of escape as the pressure and temperature
were reduced.
Since that article was written, a considerable portion of several years
has been spent by the writer continuing the observations upon which it
was based. During this time most of the mining centers of the Western
States and Territories, as well as some in Mexico and Canada, were
visited and studied with more or less care. Perhaps no other portion of
the earth's surface is so rich in mineral resources as that which has
been covered by these observations, and nowhere else is to be found as
great a variety of ore deposits, or those which illustrate as well their
mode of formation. This is so true that it maybe said without
exaggeration that no one can intelligently discuss the questions that
have been raised in regard to the origin and mode of formation of ore
bodies without transversing and studying the great mining belt of our
Western States and Territories.
The observations made by the writer during the past four years confirm
in all essentials the views set forth in the former article in the
_Quarterly_, and while a volume might be written describing the
phenomena exhibited by different mines and mining districts, the array
of facts thus presented would be, for the most part, simply a
re-enforcement of those already given.
The present article, which must necessarily be short, would hardly have
a _raison d'etre_ except that it affords an opportunity for an addition
which should be made to the classes of mineral veins heretofore
recognized in this country, and it seems called for by the recent
publication of theories on the origin of ore deposits which are
incompatible with those hitherto presented and now held by the writer,
and which, if allowed to pass unquestioned, might seem to be
unquestionable.
BEDDED VEINS.
Certain ore deposits which have recently come under my observation
appear to correspond very closely with those that Von Cotta has taken as
types of his class of "bedded veins," and as no similar ones have been
noticed by American writers on ore deposits they have seemed to me
worthy of description.
These are zones or layers of a sedimentary rock, to the bedding of which
they are conformable, impregnated with ore derived from a foreign
source, and formed long subsequent to the deposition of the containing
formation. Such deposits are exemplified by the Walker and Webster, the
Pinon, the Climax, etc., in Parley's Park, and the Green-Eyed Monster,
and the Deer Trail, at Marysvale, Utah. These are all zones in quartzite
which have been traversed by mineral solutions that have by substitution
converted such layers into ore deposits of considerable magnitude and
value.
The ore contained in these bedded veins exhibits some variety of
composition, but where unaffected by atmospheric action consists of
argentiferous galena, iron pyrites carrying gold, or the sulphides of
zinc and copper containing silver or gold or both. The ore of the Walker
and Webster and the Pinon is chiefly lead-carbonate and galena, often
stained with copper-carbonate. That of the Green Eyed Monster--now
thoroughly oxidized as far as penetrated--forms a sheet from twenty to
forty feet in thickness, consisting of ferruginous, sandy, or talcose
soft material carrying from twenty to thirty dollars to the ton in gold
and silver. The ore of the Deer Trail forms a thinner sheet containing
considerable copper, and sometimes two hundred to three hundred dollars
to the ton in silver.
The rocks which hold these ore deposits are of Silurian age, but they
received their metalliferous impregnation much later, probably in the
Tertiary, and subsequent to the period of disturbance in which they were
elevated and metamorphosed. This is proved by the fact that in places
where the rock has been shattered, strings of ore are found running off
from the main body, crossing the bedding and filling the interstices
between the fragments, forming a coarse stock-work.
Bedded veins may be distinguished from fissure veins by the absence of
all traces of a fissure, the want of a banded structure, slickensides,
selvages, etc.; from gash veins and the floors of ore which often
accompany them, as well as from segregated veins, they are distinguished
by the nature of the inclosing rock and the foreign origin of the ore.
Sometimes the plane of junction between two contiguous sheets of rock
has been the channel through which has flowed a metalliferous solution,
and the zone where the ore has replaced by substitution portions of one
or both strata. These are often called blanket veins in the West, but
they belong rather to the category of contact deposits as I have
heretofore defined them. Where such sheets of ore occupy by preference
the planes of contact between adjacent strata, but sometimes desert such
planes, and show slickensided walls, and banded structure, like the
great veins of Bingham, Utah, these should be classed as true fissure
veins.
THEORIES OF ORE DEPOSIT.
The recently published theories of the formation of mineral veins, to
which I have alluded, are those of Prof. Von Groddek[1] and Dr.
Sandberger,[2] who attribute the filling of veins to exudations of
mineral solutions from the wall rocks (i.e., lateral secretions), and
those of Mr. S.F. Emmons,[3] and Mr. G.F. Becker,[4] who have been
studying, respectively, the ore deposits of Leadville and of the
Comstock, by whom the ores are credited to the leaching of adjacent
_igneous_ rocks.
[Footnote 1: Die Lehre von den Lagerstatten der Erze, von Dr. Albrecht
von Groddek, Leipzig. 1879.]
[Footnote 2: Untersuchungen uber Erzgange, von Fridolin Sandberger,
Weisbaden, 1882.]
[Footnote 3: Geology and Mining Industry of Leadville, Annual Report,
Director U.S. Geol. Surv., 1881.]
[Footnote 4: Geology of the Comstock Lode and Washoe District, G.F.
Becker, Washington, 1883.
It is but justice to Messrs. Becker and Emmons to say that theirs are
admirable studies, thorough and exhaustive, of great interest and value
to both mining engineers and geologists, and most creditable to the
authors and the country. No better work of the kind has been done
anywhere, and it will detract little from its merit even if the views of
the authors on the theoretical question of the sources of the ores shall
not be generally adopted.]
The lack of space must forbid the full discussion of these theories at
the present time, but I will briefly enumerate some of the facts which
render it difficult for me to accept them.
First, _the great diversity of character exhibited by different sets of
fissure veins which cut the same country rock_ seems incompatible with
any theory of lateral secretion. These distinct systems are of different
ages, of diversified composition, and have evidently drawn their supply
of material from different sources. Hundreds of cases of this kind could
be cited, but I will mention only a few; among others the Humboldt, the
Bassick, and the Bull Domingo, near Rosita and Silver Cliff, Colorado.
These are veins contained in the same sheet of eruptive rock, but the
ores are as different as possible. The Humboldt is a narrow fissure
carrying a thin ore streak of high grade, consisting of sulphides of
silver, antimony, arsenic, and copper; the Bassick is a great
conglomerate vein containing tellurides of silver and gold,
argentiferous galena, blende, and yellow copper; the Bull Domingo is
also a great fissure filled with rubbish containing ore chimneys of
galena with tufts of wire silver. I may also cite the Jordan, with its
intersecting and yet distinct and totally different veins; the Galena,
the Neptune, and the American Flag, in Bingham Canon, Utah; and the
closely associated yet diverse system of veins the Ferris, the
Washington, the Chattanooga, the Fillmore, etc., in Bullion Canon at
Marysvale. In these and many other groups which have been examined by
the writer, the same rocks are cut by veins of different ages, having
different bearings, and containing different ores and veinstones. It
seems impossible that all these diversified materials should have been
derived from the same source, and the only rational explanation of the
phenomena is that which I have heretofore advocated, the ascent of
metalliferous solutions from different and deep seated sources.
Another apparently unanswerable argument against the theory of lateral
secretion is furnished by the cases _where the same vein traverses a
series of distinct formations, and holds its character essentially
unaffected by changes in the country rock_. One of many such may be
cited in the Star vein at Cherry Creek, Nevada, which, nearly at right
angles to their strike, cuts belts of quartzite, limestone, and slate,
maintaining its peculiar character of ore and gangue throughout.
This and all similar veins have certainly been filled with material
brought from a distance, and not derived from the walls.
LEACHING OF IGNEOUS ROCKS.
The arguments against the theory that mineral veins have been produced
by the leaching of superficial _igneous_ rocks are in part the same as
those already cited against the general theory of lateral secretion.
They may be briefly summarized as follows:
1. Thousands of mineral veins in this and other countries occur in
regions remote from eruptive rocks. Into this category come most of
those of the eastern half of the Continent, viz., Canada, New England,
the Alleghany belt, and the Mississippi Valley. Among those I will refer
only to a few selected to represent the greatest range of character,
viz., the Victoria lead mine, near Sault Ste. Marie, the Bruce copper
mine on Lake Huron, the gold-bearing quartz veins of Madoc, the Gatling
gold vein of Marmora, the Acton and the Harvey Hill copper mines of
Canada, the copper veins of Ely, Vermont, and of Blue Hills, Maine, the
silver-bearing lead veins of Newburyport, Mass.; most of the segregated
gold veins of the Alleghany belt, the lead veins of Rossie, Ellenville,
and at other localities farther South; the copper bearing veins of
Virginia, North Carolina, and Tennessee; the veins carrying
argentiferous galena in Central Kentucky and in Southern Illinois; the
silver, copper, and antimony veins of Arkansas; and the lead and zinc
deposits of Missouri and the Upper Mississippi.
In these widely separated localities are to be found fissure,
segregated, and gash veins, and a great diversity of ores, which have
been derived, sometimes from the adjacent rocks--as in the segregated
veins of the Alleghany belt and the gash veins of the Mississippi
region--and in other cases--where they are contained in true fissure
veins--from a foreign source, but all deposited without the aid of
superficial igneous rocks, either as contributors of matter or force.
2. In the great mineral belt of the Far West, where volcanic emanations
are so abundant, and where they have certainly played an important part
in the formation of ore deposits, the great majority of veins are not in
immediate contact with trap rocks, and they could not, therefore, have
furnished the ores.
A volume might be formed by a list of the cases of this kind, but I can
here allude to a few only, most of which I have myself examined, viz.:
_(a.)_ The great ore chambers of the San Carlos Mountains in Chihuahua,
the largest deposits of ore of which I have any knowledge. These are
contained in heavy beds of limestone, which are cut in various places by
trap dikes, which, as elsewhere, have undoubtedly furnished the stimulus
to chemical action that has resulted in the formation of the ore bodies,
but are too remote to have supplied the material.
_(b.)_ The silver mines of Santa Eulalia, in Chihuahua, from which
during the last century one hundred and twelve millions of dollars were
taken, opened on ore deposits situated in Cretaceous limestones like
those of San Carlos, and apparently similar ore-filled chambers; an
igneous rock caps the hills in the vicinity, but is nowhere in contact
or even proximity to the ore bodies. (See Kimball, _Amer. Jour. Sci,_.
March, 1870.)
_(c.)_ The great chambers of Tombstone, and the copper veins of the
Globe District, the Copper Queen, etc., in Arizona.
_(d.)_ The large bodies of silver-ore at Lake Valley, New Mexico;
chambers in limestone, like _c_.
_(e.)_ The Black Hawk group of gold mines, the Montezuma, Georgetown,
and other silver mines in the granite belt of Colorado.
_(f.)_ The great group of veins and chambers in the Bradshaw, Lincoln,
Star, and Granite districts of Southern Utah, where we find a host of
veins of different character in limestone or granite, with no trap to
which the ores can be credited.
_(g.)_ The Crismon Mammoth vein of Tintic.
_(h.)_ The group of mines opened on the American Fork, on Big and Little
Cottonwood, and in Parley's Park, including the Silver Bell, the Emma,
the Vallejo, the Prince of Wales, the Kessler, the Bonanza, the Climax,
the Pinon, and the Ontario. (The latter, the greatest silver mine now
known in the country, lies in quartzite, and the trap is near, but not
in contact with the vein.)
_(i.)_ In Nevada, the ore deposits of Pioche, Tempiute, Tybo, Eureka,
White Pine, and Cherry Creek, on the east side of the State, with those
of Austin, Belmont, and a series too great for enumeration in the
central and western portions.
_(j.)_ In California, the Bodie, Mariposa, Grass Valley, and other
mines.[1]
_(k.)_ In Idaho, those of the Poor Man in the Owyhee district, the
principal veins of the Wood River region, the Ramshorn at Challis, the
Custer and Charles Dickens, at Bonanza City, etc.
[Footnote 1: See Redmond's Report _(California Geol. Survey Mining
Statistics, No 1),_ where seventy-seven mines are enumerated, of which
three are said to be in "porphyritic schist," all the others in granite,
mica schist, clay, slate, etc.]
In nearly all these localities we may find evidence not only that the
ore deposits have not been derived from the leaching of igneous rocks,
but also that they have not come from those of any kind which form the
walls of the veins.
The gold-bearing quartz veins of Deadwood are so closely associated with
dikes of porphyry, that they may have been considered as illustrations
of the potency of trap dikes in producing concentration of metals. But
we have conclusive evidence that the gold was there in Archaean times,
while the igneous rocks are all of modern, probably of Tertiary, date.
This proof is furnished by the "Cement mines" of the Potsdam sandstone.
This is the beach of the Lower Silurian sea when it washed the shores of
an Archaean island, now the Black Hills. The waves that produced this
beach beat against cliffs of granite and slate containing quartz veins
carrying gold. Fragments of this auriferous quartz, and the gold beaten
out of them and concentrated by the waves, were in places buried in the
sand beach in such quantity as to form deposits from which a large
amount of gold is now being taken. Without this demonstration of the
origin and antiquity of the gold, it might very well have been supposed
to be derived from the eruptive rock.
Strong arguments against the theory that the leaching of superficial
igneous rocks has supplied the materials filling mineral veins, are
furnished by the facts observed in the districts where igneous rocks are
most prevalent, viz.: (1.) _Such districts are proverbially barren of
useful minerals_. (2.) _Where these occur, the same sheet of rock may
contain several systems of veins with different ores and gangues._
The great lava plain of Snake River, the Pedrigal country of eastern
Oregon, Northern California and Mexico are without valuable ore
deposits. The same may be said of the Pancake Range and other mountain
chains of igneous rock in Nevada, while the adjacent ranges composed of
sedimentary rocks are rich in ore deposits of various kinds. A still
stronger case is furnished by the Cascade Mountains, which, north of the
California line, are composed almost exclusively of erupted material,
and yet in all this belt, so far as now known, not a single valuable
mine has been opened. In contrast with this is the condition of things
in California, where the Sierra Nevada is composed of metamorphic rocks
which have been shown to be the repositories of vast quantities of gold,
silver, and copper. Cases belonging to this category may be found at
Rosita and Silver Cliff, where the diversity in the ores of the mines
already enumerated can hardly be reconciled with the theory of a common
origin. At Lake City the prevailing porphyry holds the veins of the Ute
and Ulay and the Ocean Wave mines, which are similar, and the Hotchkiss,
the Belle, etc., entirely different.
We have no evidence that any volcanic eruption has drawn its material
from zones or magmas especially rich in metals or their ores, and on the
contrary, volcanic districts, like those mentioned, and regions, such as
the Sandwich Islands, where the greatest, eruptions have taken place,
are poorest in metalliferous deposits.
All the knowledge we have of the subject justifies the inference that
most of the igneous rocks which have been poured out in our Western
Territories are but fused conditions of sediments which form the
substructure of that country. Over the great mineral belt which lies
between the Sierra Nevada and the front range of the Rocky Mountains,
and extends not only across the whole breadth of our territory, but far
into Mexico, the surface was once underlain by a series of Palaeozoic
sedimentary strata not less than twenty to thirty thousand feet in
thickness; and beneath these, at the sides, and doubtless below, were
Archaeun rocks, also metamorphosed sediments. Through these the ores of
the metals were generally though sparsely distributed. In the
convulsions which have in recent times broken up this so long quiet and
stable portion of the earth's crust (and which have resulted in
depositing in thousands of cracks and cavities the ores we now mine),
portions of the old table-land were in places set up at high angles
forming mountain chains, and doubtless extending to the zone of fusion
below. Between these blocks of sedimentary rocks oozed up through the
lines of fracture quantities of fused material, which also sometimes
formed mountain chains; and it is possible and even probable that the
rocks composing the volcanic ridges are but phases of the same materials
that form the sedimentary chains There is, therefore, no _a priori_
reason why the leaching of one group should furnish more ore than the
other; but, as a matter of fact, the unfused sediments are much the
richer in ore deposits. This can only be accounted for, in my judgment,
by supposing that they have been the receptacles of ore brought from a
foreign source; and we can at least conjecture where and how gathered.
We can imagine, and we are forced to conclude, that there has been a
zone of solution below, where steam and hot water, under great pressure,
have effected the leaching of ore-bearing strata, and a zone of
deposition above, where cavities in pre-existent solidified and
shattered rocks became the repositories of the deposits made from
ascending solutions, when the temperature and pressure were diminished.
Where great masses of fused material were poured out, these must have
been for along time too highly heated to become places of deposition; so
long indeed that the period of active vein formation may have passed
before they reached a degree of solidification and coolness that would
permit their becoming receptacles of the products of deposition. On the
contrary, the masses of unfused and always relatively cool sedimentary
rocks which form the most highly metalliferous mountain ranges (White
Pine, Toyabe, etc.) were, throughout the whole period of disturbance, in
a condition to become such repositories. Certainly highly heated
solutions forced by an irresistible _vis a tergo_ through rocks of any
kind down in the heated zone, would be far more effective leaching
agents than cold surface water with feeble solvent power, moved only by
gravity, percolating slowly through superficial strata.
Richthofen, who first made a study of the Comstock lode, suggests that
the mineral impregnation of the vein was the result of a process like
that described, viz., the leaching of deep-seated rocks, perhaps the
same that inclose the vein above, by highly heated solutions which
deposited their load near the surface. On the other hand, Becker
supposes the concentration to have been effected by surface waters
flowing laterally through the igneous rocks, gathering the precious
metals and depositing them in the fissure, as lateral secretion produces
the accumulation of ore in the limestone of the lead region. But there
are apparently good reasons for preferring the theory of Richthofen:
viz., first, the veinstone of the Comstock is chiefly quartz, the
natural and common precipitate of _hot_ waters, since they are far more
powerful solvents of silica than cold. On the contrary, the ores
deposited from lateral secretion, as in the Mississippi lead region, at
low temperature contain comparatively little silica; second, the great
mineral belt to which reference has been made above is now the region
where nearly all the hot springs of the continent are situated. It is,
in fact, a region conspicuous for the number of its hot springs, and it
is evident that these are the last of the series of thermal phenomena
connected with the great volcanic upheavals and eruptions, of which this
region has been the theater since the beginning of the Tertiary age. The
geysers of Yellowstone Park, the hot springs of the Wamchuck district in
Oregon, the Steamboat Springs of Nevada, the geysers of California, the
hot springs of Salt Lake City, Monroe, etc., in Utah, and the Pagosa in
Colorado, are only the most conspicuous among thousands of hot springs
which continue in action at the present time. The evidence is also
conclusive that the number of hot springs, great as it now is in this
region, was once much greater. That these hot springs were capable of
producing mineral veins by material brought up in and deposited from
their waters, is demonstrated by the phenomena observable at the
Steamboat Springs, and which were cited in my former article as
affording the best illustration of vein formation.
The temperature of the lower workings of the Comstock vein is now over
150 deg.F., and an enormous quantity of hot water is discharged through the
Sutro Tunnel. This water has been heated by coming in contact with hot
rocks at a lower level than the present workings of the Comstock lode,
and has been driven upward in the same way that the flow of all hot
springs is produced. As that flow is continuous, it is evident that the
workings of the Comstock have simply opened the conduits of hot springs,
which are doing to-day what they have been doing in ages past, but much
less actively, i.e., bringing toward the surface the materials they have
taken into solution in a more highly heated zone below. Hence it seems
much more natural to suppose that the great sheets of ore-bearing quartz
now contained in the Comstock fissure were deposited by ascending
currents of hot alkaline waters, than by descending currents of those
which were cold and neutral The hot springs are there, though less
copious and less hot than formerly, and the natural deposits from hot
waters are there. Is it not more rational to suppose with Richthofen
that these are related as cause and effect, rather than that cold water
has leached the ore and the silica from the walls near the surface? Mr.
Becker's preference for the latter hypothesis seems to be due to the
discovery of gold and silver in the igneous rocks adjacent to the vein,
and yet, except in immediate contact with it, these rocks contain no
more of the precious metals than the mere trace which by refined tests
may be discovered everywhere. If, as we have supposed, the fissure was
for a long time filled with a hot solution charged with an unusual
quantity of the precious metals, nothing would be more natural than that
the wall rocks should be to some extent impregnated with them.
It will perhaps illuminate the question to inquire which of the springs
and water currents of this region are now making deposits that can be
compared with those which filled the Comstock and other veins. No one
who has visited that country will hesitate to say the hot and not the
cold waters. The immense silicious deposits, carrying the ores of
several metals, formed by the geysers of the Yellowstone, the Steamboat
Springs, etc., show what the hot waters are capable of doing; but we
shall search in vain for any evidence that the cold surface waters have
done or can do this kind of work.
At Leadville the case is not so plain, and yet no facts can be cited
which really _prove_ that the ore deposits have been formed by the
leaching of the overlying porphyry rather than by an outflow of heated
mineral solutions along the plane of junction between the porphyry and
the limestone. Near this plane the porphyry is often thoroughly
decomposed, is somewhat impregnated with ore, and even contains sheets
of ore within itself; but remote from the plane of contact with the
limestone, it contains little diffused and no concentrated ore. It is
scarcely more previous than the underlying limestones, and why a
solution that could penetrate and leach ores from it should be stopped
at the upper surface of the blue limestone is not obvious; nor why the
plane of junction between the porphyry and the _blue limestone_ should
be the special place of deposit of the ore.
If the assays of the porphyry reported by Mr. Emmons were accurately
made, and they shall be confirmed by the more numerous ones necessary to
settle the question, and the estimates he makes of the richness of that
rock be corroborated, an unexpected result will be reached, and, as I
think, a remarkable and exceptional case of the diffusion of silver and
lead through an igneous rock be established.
It is of course possible that the Leadville porphyries are only phases
of rocks rich in silver, lead, and iron, which underlie this region, and
which have been fused and forced to the surface by an ascending mass of
deeper seated igneous rock; but even if the argentiferous character of
the porphyry shall be proved, it will not be proved that such portions
of it as here lie upon the limestone have furnished the ore by the
descending percolation of cold surface waters. Deeper lying masses of
this same silver, lead, and iron bearing rock, digested in and leached
by _hot_ waters and steam under great pressure, would seem to be a more
likely source of the ore. If the surface porphyry is as rich in silver
as Mr. Emmous reports it to be, it is too rich, for the rock that has
furnished so large a quantity of ores as that which formed the ore
bodies which I saw in the Little Chief and Highland Chief mines,
respectively 90 feet and 162 feet thick, should be poor in silver and
iron and lead, and should be rotten from the leaching it had suffered,
but except near the ore-bearing contact it is compact and normal.
Such a digested, kaolinized, desilicated rock as we would naturally look
for we find in the porphyry _near the contact_; and its condition there,
so different from what it is remote from the contact, seems to indicate
an exposure to local and decomposing influences, such indeed as a hot
chemical solution forced up from below along the plane of contact would
furnish.
It is difficult to understand why the upper portions of the porphyry
sheet should be so different in character, so solid and homogeneous,
with no local concentrations or pockets of ore, if they have been
exposed to the same agencies as those which have so changed the under
surface.
Accepting all the facts reported by Mr. Emmons, and without questioning
the accuracy of any of his observations, or depreciating in any degree
the great value of the admirable study he has made of this difficult and
interesting field, his conclusion in regard to the source of the ore
cannot yet be insisted on as a logical necessity. In the judgment of the
writer, the phenomena presented by the Leadville ore deposits can be as
well or better accounted for by supposing that the plane of contact
between the limestone and porphyry has been the conduit through which
heated mineral solutions coming from deep seated and remote sources have
flowed, removing something from both the overlying and underlying
strata, and by substitution depositing sulphides of lead, iron, silver,
etc., with silica.
The ore deposits of Tybo and Eureka in Nevada, of the Emma, the Cave,
and the Horn Silver [1] mines in Utah, have much in common with those of
Leadville, and it is not difficult to establish for all of the former
cases a foreign and deep seated source of the ore. The fact that the
Leadville ore bodies are sometimes themselves excavated into chambers,
which has been advanced as proof of the falsity of the theory here
advocated, has no bearing on the question, as in the process of
oxidation of ores which were certainly once sulphides, there has been
much change of place as well as character; currents of water have flowed
through them which have collected and redeposited the cerusite in sheets
of "hard carbonate" or "sand carbonate," and have elsewhere produced
accumulations of kerargyrite, perhaps thousands of years after the
deposition of the sulphide ores had ceased and the oxidation had begun.
In the leaching and rearrangement of the ore bodies, nothing would be
more natural than that accumulations in one place should be attended by
the formation of cavities elsewhere.
[Footnote 1: The Horn Silver ore body lies in a fault fissure between a
footwall of limestone and a hanging wall of trachyte, and those who
consider the Leadville ores as teachings of the overlying porphyry would
probably also regard the ore of the Horn Silver mine as derived from the
trachyte hanging wall; but three facts oppose the acceptance of this
view, viz., let, the trachyte, except in immediate contact with the ore
body, seems to be entirely barren; 2d, the Horn Silver ore "chimney,"
perhaps fifty feet thick, five hundred feet wide, and of unknown depth,
is the only mass of ore yet found in a mile of well marked fissure; and
3d, the Carbonate mine opened near by in a strong fissure with a bearing
at right angles to that of the Horn Silver, and lying entirely within
the trachyte, yields ore of a totally different kind. Both are opened to
the depth of seven hundred feet with no signs of change or exhaustion.
If the ore were derived from the trachyte, it should be at least
somewhat alike in the two mines, should be more generally distributed in
the Horn Silver fissure, and might be expected to give out at, no great
depth.
If deposited by solutions coming from deep and different sources, the
observed differences in character would be natural; it would accumulate
as we find it in the channels of outflow, and would be as time will
probably prove it, perhaps variable in quantity, but indefinitely
continuous in depth.]
Another question which suggests itself in reference to the Leadville
deposits is this: If the Leadville ore was once a mass of sulphides
derived from the overlying porphyry by the percolation of surface
waters, why has the deposit ceased? The deposition of galena, blende,
and pyrite in the Galena lead mines still continues. If the leaching of
the Leadville porphyry has not resulted in the formation of alkaline
sulphide solutions, and the ore has come from the porphyry in the
condition of carbonate of lead, chloride of silver, etc., then the
nature of the deposition was quite different from that of the similar
ones of Tybo, Eureka, Bingham, etc., which are plainly gossans, and
indeed is without precedent. But if the process was similar to that in
the Galena lead region, and the ores were originally sulphides, their
formation should have continued and been detected in the Leadville
mines.
For all these reasons the theory of Mr. Emmons will be felt to need
further confirmation before it is universally adopted.
From what has gone before it must not be inferred that lateral secretion
is excluded by the writer from the list of agencies which have filled
mineral veins, for it is certain that the nature of the deposit made in
the fissure has frequently been influenced by the nature of the adjacent
wall rock. Numerous cases may be cited where the ores have increased or
decreased in quantity and richness, or have otherwise changed character
in passing from one formation to another; but even here the proof is
generally wanting that the vein materials have been furnished by the
wall rocks opposite the places where they are found.
The varying conductivity of the different strata in relation to heat and
electricity may have been an important factor. Trap dikes frequently
enrich veins where they approach or intersect them, and they have often
been the _primum mobile_ of vein formation, but chiefly, if not only, by
supplying heat, the mainspring of chemical action. The proximity of
heated masses of rock has promoted chemical action in the same way as do
the Bunsen burners or the sand baths in the laboratory; but no case has
yet come under my observation where it was demonstrable that the filling
of a fissure vein had been due to secretion from igneous or sedimentary
wall rocks.
In the Star District of Southern Utah the country rock is Palaeozoic
limestone, and it is cut by so great a number and variety of mineral
veins that from the Harrisburg, a central location, a rifle shot would
reach ten openings, all on as many distinct and different veins (viz.,
the Argus, Little Bilk, Clean Sweep, Mountaineer, St. Louis, Xenia,
Brant, Kannarrah, Central, and Wateree). The nearest trap rock is half a
mile or more distant, a columnar dike perhaps fifteen feet in thickness,
cutting the limestone vertically. On either side of this dike is a vein
from one to three feet in thickness, of white quartz with specks of ore.
Where did that quartz come from? From the limestone? But the limestone
contains very little silica, and is apparently of normal composition
quite up to the vein. From the trap? This is compact, sonorous basalt,
apparently unchanged; and that could not have supplied the silica
without complete decomposition.
I should rather say from silica bearing hot waters that flowed up along
the sides of the trap, depositing there, as in the numerous and varied
veins of the vicinity, mineral matters brought from a zone of solution
far below.
To summarize the conclusions reached in this discussion. I may repeat
that the results of all recent as well as earlier observations has been
to convince me that Richthofen's theory of the filling of the Comstock
lode is the true one, and that the example and demonstration of the
formation of mineral veins furnished by the Steamboat Springs is not
only satisfactory, but typical.
* * * * *
[NATURE.]
HABITS OF BURROWING CRAYFISHES IN THE UNITED STATES.
On May 13, 1883, I chanced to enter a meadow a few miles above
Washington, on the Virginia side of the Potomac, at the head of a small
stream emptying into the river. It was between two hills, at an
elevation of 100 feet above the Potomac, and about a mile from the
river. Here I saw many clayey mounds covering burrows scattered over the
ground irregularly both upon the banks of the stream and in the adjacent
meadow, even as far as ten yards from the bed of the brook. My curiosity
was aroused, and I explored several of the holes, finding in each a
good-sized crayfish, which Prof. Walter Faxon identified as _Cambarus
diogenes_, Girard _(C. obesus_, Hagen), otherwise known as the burrowing
crayfish. I afterward visited the locality several times, collecting
specimens of the mounds and crayfishes, which are now in the United
States National Museum, and making observations.
At that time of the year the stream was receding, and the meadow was
beginning to dry. At a period not over a month previous, the meadows, at
least as far from the stream as the burrows were found, had been covered
with water. Those burrows near the stream were less than six inches
deep, and there was a gradual increase in depth as the distance from the
stream became greater. Moreover, the holes farthest from the stream were
in nearly every case covered by a mound, while those nearer had either a
very small chimney or none at all, and subsequent visits proved that at
that time of year the mounds were just being constructed, for each time
I revisited the place the mounds were more numerous.
[Illustration: Fig. 1 Section of Crayfish burrow]
The length, width, general direction of the burrows, and number of the
openings were extremely variable, and the same is true of the mounds.
Fig. 1 illustrates a typical burrow shown in section. Here the main
burrow is very nearly perpendicular, there being but one oblique opening
having a very small mound, and the main mound is somewhat wider than
long. Occasionally the burrows are very tortuous, and there are often
two or three extra openings, each sometimes covered by a mound. There is
every conceivable shape and size in the chimneys, ranging from a mere
ridge of mud, evidently the first foundation, to those with a breadth
one-half the height. The typical mound is one which covers the
perpendicular burrow in Fig. 1, its dimensions being six inches broad
and four high. Two other forms are shown in Fig. 2. The burrows near the
stream were seldom more than six inches deep, being nearly
perpendicular, with an enlargement at the base, and always with at least
one oblique opening. The mounds were usually of yellow clay, although in
one place the ground was of fine gravel, and there the chimneys were of
the same character. They were always circularly pyramidal in shape, the
hole inside being very smooth, but the outside was formed of irregular
nodules of clay hardened in the sun and lying just as they fell when
dropped from the top of the mound. A small quantity of grass and leaves
was mixed through the mound, but this was apparently accidental.
The size of the burrows varied from half an inch to two inches in
diameter, being smooth for the entire distance, and nearly uniform in
width. Where the burrow was far distant from the stream, the upper part
was hard and dry. In the deeper holes I invariably found several
enlargements at various points in the burrow. Some burrows were three
feet deep, indeed they all go down to water, and, as the water in the
ground lowers, the burrow is undoubtedly projected deeper. The diagonal
openings never at that season of the year have perfect chimneys, and
seldom more than a mere rim. In no case did I find any connection
between two different burrows. In digging after the inhabitants I was
seldom able to secure a specimen from the deeper burrows, for I found
that the animal always retreated to the extreme end, and when it could
go no farther would use its claws in defense. Both males and females
have burrows, but they were never found together, each burrow having but
a single individual. There is seldom more than a pint of water in each
hole, and this is muddy and hardly suitable to sustain life.
[Illustration: Fig. 2 Crayfish Mound]
The neighboring brooks and springs were inhabited by another species of
crayfish, _Cambaras bartonii_, but although especial search was made for
the burrowing species, in no case was a single specimen found outside of
the burrows. _C. bartonii_ was taken both in the swiftly running
portions of the stream and in the shallow side pools, as well as in the
springs at the head of small rivers. It would swim about in all
directions, and was often found under stones and in little holes and
crevices, none of which appeared to have been made for the purpose of
retreat, but were accidental. The crayfishes would leave these little
retreats whenever disturbed, and swim away down stream out of sight.
They were often found some distance from the main stream under rocks
that had been covered by the brook at a higher watermark; but although
there was very little water under the rocks, and the stream had not
covered them for at least two weeks, they showed no tendency to burrow.
Nor have I ever found any burrows formed by the river species _Cumbarus
affinis._ although I have searched over miles of marsh land on the
Potomac for this purpose.
[Illustration: Fig. 2 Crayfish Mound (shorter)]
The brook near where my observations were made was fast decreasing in
volume, and would probably continue to do so until in July its bed would
be nearly dry. During the wet seasons the meadow is itself covered. Even
in the banks of the stream, then under water, there were holes, but they
all extended obliquely without exception, there being no perpendicular
burrows and no mounds. The holes extended in about six inches, and there
was never a perpendicular branch, nor even an enlargement at the end. I
always found the inhabitant near the mouth, and by quickly cutting off
the rear part of the hole could force him out, but unless forcibly
driven out it would never leave the hole, not even when a stick was
thrust in behind it. It was undoubtedly this species that Dr. Godman
mentioned in his "Rambles of a Naturalist," and which Dr. Abbott _(Am.
Nal.,_ 1873, p. 81) refers to _C. bartonii_. Although I have no proof
that this is so, I am inclined to believe that the burrowing crayfishes
retire to the stream in winter and remain there until early spring, when
they construct their burrows for the purpose of rearing their young and
escaping the summer droughts. My reason for saying this is that I found
one burrow which on my first visit was but six inches deep, and later
had been projected to a depth at least twice as great, and the
inhabitant was an old female.
I think that after the winter has passed, and while the marsh is still
covered with water, impregnation takes place and burrows are immediately
begun. I do not believe that the same burrow is occupied for more than
one year, as it would probably fill up during the winter. At first it
burrows diagonally, and as long as the mouth is covered with water is
satisfied with this oblique hole. When the water recedes, leaving the
opening uncovered, the burrow must be dug deeper, and the economy of a
perpendicular burrow must immediately suggest itself. From that time the
perpendicular direction is preserved with more or less regularity.
Immediately after the perpendicular hole is begun, a shorter opening to
the surface is needed for conveying the mud from the nest, and then the
perpendicular opening is made. Mud from this, and also from the first
part of the perpendicular burrow, is carried out of the diagonal opening
and deposited on the edge. If a freshet occurs before this rim of mud
has had a chance to harden, it is washed away, and no mound is formed
over the oblique burrow.
After the vertical opening is made, as the hole is bored deeper, mud is
deposited on the edge, and the deeper it is dug the higher the mound. I
do not think that the chimney is a necessary part of the nest, but
simply the result of digging. I carried away several mounds, and in a
week revisited the place, and no attempt had been made to replace them;
but in one case, where I had in addition partly destroyed the burrow by
dropping mud into it, there was a simple half rim of mud around the
edge, showing that the crayfish had been at work; and as the mud was dry
the clearing must have been done soon after my departure. That the
crayfish retreats as the water in the ground falls lower and lower is
proved by the fact that at various intervals there are bottled-shaped
cavities marking the end of the burrow at an earlier period. A few of
those mounds farthest from the stream had their mouths closed by a
pellet of mud. It is said that all are closed during the summer months.
How these animals can live for months in the muddy, impure water is to
me a puzzle. They are very sluggish, possessing none of the quick
motions of their allied _C. bartonii,_ for when taken out and placed
either in water or on the ground, they move very slowly. The power of
throwing off their claws when these are grasped is often exercised.
About the middle of May the eggs hatch, and for a time the young cling
to the mother, but I am unable to state how long they remain thus. After
hatching they must grow rapidly, and soon the burrow will be too small
for them to live in, and they must migrate. It would be interesting to
know more about the habits of this peculiar species, about which so
little has been written. An interesting point to settle would be how and
where it gets its food. The burrow contains none, either animal or
vegetable. Food must be procured at night, or when the sun is not
shining brightly. In the spring and fall the green stalks of meadow
grasses would furnish food, but when these become parched and dry they
must either dig after and eat the roots, or search in the stream. I feel
satisfied that they do not tunnel among the roots, for if they did so
these burrows would be frequently met with. Little has as yet been
published upon this subject, and that little covers only two spring
months--April and May--and it would be interesting if those who have an
opportunity to watch the species during other seasons, or who have
observed them at any season of the year, would make known their results.
RALPH S. TARR
* * * * *
OUR SERVANTS, THE MICROBES.
Who of us has not, in a partially darkened room, seen the rays of the
sun, as they entered through apertures or chinks in the shutters,
exhibit their track by lighting up the infinitely small corpuscles
contained in the air? Such corpuscles always exist, except in the
atmosphere of lofty mountains, and they constitute the dust of the air.
A microscopic examination of them is a matter of curiosity. Each flock
is a true museum (Fig. 1), wherein we find grains of mineral substances
associated with organic debris, and germs of living organisms, among
which must be mentioned the _microbes_.
Since the splendid researches of Mr. Pasteur and his pupils on
fermentation and contagious diseases, the question of microbes has
become the order of the day.
In order to show our readers the importance of the study of the
microbes, and the results that may be reached by following the
scientific method created by Mr. Pasteur, it appears to us indispensable
to give a summary of the history of these organisms. In the first place,
what is a microbe? Although much employed, the word has not been well
defined, and it would be easy to find several definitions of it. In its
most general sense, the term microbe designates certain colorless algae
belonging to the family Bacteriaceae, the principal forms of which are
known under the name of _Micrococcus. Bacterium, Bacillus. Vibrio,
/Spirillum, etc_.
In order to observe these different forms of Bacteriaceae it is only
necessary to examine microscopically a drop of water in which organic
matter has been macerated, when there will be seen _Micrococci_ (Fig. 2,
I.)looking like spherical granules, _Bacteria_ in the form of very short
rods, _Bacilli_ (Fig. 2, V.), _Vibriones_ (Fig. 2, IV.,) moving their
straight or curved filaments, and _Spirilli_ (Fig. 2, VI.), rolled up
spirally. These varied forms are not absolutely constant, for it often
happens in the course of its existence that a species assumes different
shapes, so that it is difficult to take the form of these algae as a
basis for classifying them, when all the phases of their development
have not been studied.
The Bacteriaceae are reproduced with amazing rapidity. If the temperature
is proper, a limpid liquid such as chicken or veal broth will, in a few
hours, become turbid and contain millions of these organisms.
Multiplication is effected through fission, that is to say, each globule
or filament, after elongating, divides into two segments, each of which
increases in its turn, to again divide into two parts, and so on (Fig.
2, I. b). But multiplication in this way only takes place when the
bacteria are placed in a proper nutritive liquid; and it ceases when the
liquid becomes impoverished and the conditions of life become difficult.
It is at this moment that the formation of _spores_ occurs--reproductive
bodies that are destined to permit the algae to traverse, without
perishing, those phases where life is impossible. The spores are small,
brilliant bodies that form in the center or at the extremity of each
articulation or globule of the bacterium (Fig. 2, II. l), and are set
free through the breaking up of the joints. There are, therefore, two
phases to be distinguished in the life of microbes--that of active life,
during which they multiply with great rapidity, are most active, and
cause sicknesses or fermentations, and that of retarded life, that is to
say, the state, of resting spores in which the organisms are inactive
and consequently harmless. It is curious to find that the resistance to
the two causes of destruction is very different in the two cases.
In the state of active life the bacterides are killed by a temperature
of from 70 to 80 degrees, while the spores require the application of a
temperature of from 100 to 120 degrees to kill them. Oxygen of a high
pressure, which is, as well known from Bert's researches, a poison for
living beings, kills many bacteria in the state of active life, but has
no influence upon their spores.
In a state of active life the bacteriae are interesting to study. The
absence of green matter prevents them from feeding upon mineral matter,
and they are therefore obliged to subsist upon organic matter, just as
do plants that are destitute of chlorophyl (such as fungi, broomrapes,
etc.). This is why they are only met with in living beings or upon
organic substances. The majority of these algae develop very well in the
air, and then consume oxygen and exhale carbonic acid, like all living
beings. If the supply of air be cut off, they resist asphyxia and take
the oxygen that they require from the compounds that surround them. The
result is a complete and rapid decomposition of the organic materials,
or a fermentation. Finally, there are even certain species that die in
the presence of free oxygen, and that can only live by protecting
themselves from contact with this gas through a sort of jelly. These are
ferments, such as _Bacillus amylobacter,_ or butyric ferment, and _B.
septicus_, or ferment of the putrefaction of nitrogenized substances.
[Illustration: FIG. 1.--ATMOSPHERIC DUST.]
These properties explain the regular distribution of bacteria in liquids
exposed to the air. Thus, in water in which plants have been macerated
the surface of the liquid is occupied by _Bacillus subtilis_. which has
need of free oxygen in order to live, while in the bulk of the liquid,
in the vegetable tissues, we find other bacteria, notably _B.
amylobacter_, which lives very well by consuming oxygen in a state of
combination. Bacteria, then, can only live in organic matters, now in
the presence and now in the absence of air.
What we have just said allows us to understand the process of
cultivating these organisms. When it is desired to obtain these algae,
we must take organic matters or infusions of such. These liquids or
substances are heated to at least 120 deg. in order to kill the germs that
they may contain, and this is called "sterilizing." In this sterilized
liquid are then sown the bacteria that it is desired to study, and by
this means they can be obtained in a state of very great purity.
The Bacteriaceae are very numerous. Among them we must distinguish those
that live in inert organic matters, alimentary substances, or debris of
living beings, and which cause chemical decompositions called
fermentations. Such are _Mycoderma aceti_, which converts the alcohol of
fermented beverages into vinegar; _Micrococcus ureae_, which converts
the urea of urine into carbonate of ammonia, and _Micrococcus
nitrificans,_ which converts nitrogenized matters into intrates, etc.
Some, that live upon food products, produce therein special coloring
matters; such are the bacterium of blue milk, and _Micrococcus
prodigiosus_ (Fig. 2, I.), a red alga that lives upon bread and forms
those bloody spots that were formerly considered by the superstitious as
the precursors of great calamities.
[Illustration: Fig. 2.--VARIOUS MICROBES. (Highly magnified.)]
Another group of bacteria has assumed considerable importance in
pathology, and that is the one whose species inhabit the tissues of
living animals, and cause more or less serious alterations therein, and
often death. Most contagious diseases and epidemics are due to algae of
this latter group. To cite only those whose origin is well known, we may
mention the bacterium that causes charbon, the micrococcus of chicken
cholera, and that of hog measles.
It will be seen from this sketch how important the study of these
organisms is to man, since be must defend his body against their
invasions or utilize them for bringing about useful chemical
modifications in organic matters.
_Our Servants._--We scarcely know what services microbes may render us,
yet the study of them, which has but recently been begun, has already
shown, through the remarkable labors of Messrs. Pasteur, Schloesing and
Muntz, Van Tieghem, Cohn, Koch, etc., the importance of these organisms
in nature. All of us have seen wine when exposed to air gradually sour,
and become converted into vinegar, and we know that in this case the
surface of the liquid is covered with white pellicles called "mother of
vinegar." These pellicles are made up of myriads of globules of
_Mycoderma aceti_. This mycoderm is the principal agent in the
acidification of wine, and it is it that takes oxygen from the air and
fixes it in the alcohol to convert it into vinegar. If the pellicle that
forms becomes immersed in the liquid, the wine will cease to sour.
The vinegar manufacturers of Orleans did not suspect the role of the
mother of vinegar in the production of this article when they were
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