Scientific American Supplement No. 275
by
Various
Part 2 out of 3
electricity and light have been discovered, and at the present time they
are tumbling in in great numbers.
It was found by Faraday that many other transparent media besides heavy
glass would show the phenomenon if placed between the poles, only in a less
degree; and the very important observation that air itself exhibits the
same phenomenon, though to an exceedingly small extent, has just been made
by Kundt and Rontgen in Germany.
Dr. Kerr, of Glasgow, has extended the result to opaque bodies, and has
shown that if light be passed through magnetized _iron_ its plane is
rotated. The film of iron must be exceedingly thin, because of its opacity,
and hence, though the intrinsic rotating power of iron is undoubtedly very
great, the observed rotation is exceedingly small and difficult to observe;
and it is only by a very remarkable patience and care and ingenuity that
Dr. Kerr has obtained his result. Mr. Fitzgerald, of Dublin, has examined
the question mathematically, and has shown that Maxwell's theory would have
enabled Dr. Kerr's result to be predicted.
Another requirement of the theory is that bodies which are transparent
to light must be insulators or non-conductors of electricity, and that
conductors of electricity are necessarily opaque to light. Simple
observation amply confirms this; metals are the best conductors, and are
the most opaque bodies known. Insulators such as glass and crystals are
transparent whenever they are sufficiently homogeneous, and the very
remarkable researches of Prof. Graham Bell in the last few months have
shown that even _ebonite_, one of the most opaque insulators to ordinary
vision, is certainly transparent to some kinds of radiation, and
transparent to no small degree.
[The reason why transparent bodies must insulate, and why conductors must
be opaque, was here illustrated by mechanical models.]
A further consequence of the theory is that the velocity of light in a
transparent medium will be affected by its electrical strain constant; in
other words, that its refractive index will bear some close but not yet
quite ascertained relation to its specific inductive capacity. Experiment
has partially confirmed this, but the confirmation is as yet very
incomplete. But there are a number of results not predicted by theory, and
whose connection with the theory is not clearly made out. We have the fact
that light falling on the platinum electrode of a voltameter generates a
current, first observed, I think, by Sir W. R. Grove--at any rate, it is
mentioned in his "Correlation of Forces"--extended by Becquerel and Robert
Sabine to other substances, and now being extended to fluorescent and other
bodies by Prof. Minchin. And finally--for I must be brief--we have
the remarkable action of light on selenium. This fact was discovered
accidentally by an assistant in the laboratory of Mr. Willoughby Smith, who
noticed that a piece of selenium conducted electricity very much better
when light was falling upon it than when it was in the dark. The light of
a candle is sufficient, and instantaneously brings down the resistance to
something like one-fifth of its original value.
I could show you these effects, but there is not much to see; it is an
intensely interesting phenomenon, but its external manifestation is not
striking--any more than Faraday's heavy glass experiment was.
This is the phenomenon which, as you know, has been utilized by Prof.
Graham Bell in that most ingenious and striking invention, the photophone.
By the kindness of Prof. Silvanus Thompson, I have a few slides to show the
principle of the invention, and Mr. Shelford Bidwell has been kind enough
to lend me his home-made photophone, which answers exceedingly well for
short distances.
I have now trespassed long enough upon your patience, but I must just
allude to what may very likely be the next striking popular discovery; and
that is the transmission of light by electricity; I mean the transmission
of such things as views and pictures by means of the electric wire. It has
not yet been done, but it seems already theoretically possible, and it may
very soon be practically accomplished.
* * * * *
INTERESTING ELECTRICAL RESEARCHES.
During the last six years Dr. Warren de la Rue has been investigating,
in conjunction with Dr. Hugo Muller, the various and highly interesting
phenomena which accompany the electric discharge. From time to time the
results of their researches were communicated to the Royal Society, and
appeared in its Proceedings. Early last year Dr. De la Rue being requested
to bring the subject before the members of the Royal Institution, acceded
to the pressing invitation of his colleagues and scientific friends.
The discourse, which was necessarily long postponed on account of the
preparations that had to be made, was finally given on Friday, the 21st of
January, and was one of the most remarkable, from the elaborate nature of
the experiments, ever delivered in the theater of that deservedly famous
institution.
Owing to the great inconvenience of removing the battery from his
laboratory, Dr. de la Rue, despite the great expenditure, directed Mr. S.
Tisley to prepare, expressly for the lecture, a second series of 14,400
cells, and fit it up in the basement of the Royal Institution. The
construction of this new battery occupied Mr. Tisley a whole year, while
the charging of it extended over a fortnight.
The "de la Rue cell," if we may so call one of these elements, consists of
a zinc rod, the lower portion of which is embedded in a solid electrolyte,
viz., chloride of silver, with which are connected two flattened silver
wires to serve as electrodes. When these are united and the silver chloride
moistened, chemical action begins, and a weak but constant current is
generated.
The electromotive force of such a cell is 1.03 volts, and a current
equivalent to one volt passing through a resistance of one ohm was found to
decompose 0.00146 grain of water in one second. The battery is divided
into "cabinets," which hold from 1,200 to 2,160 small elements each. This
facilitates removal, and also the detection of any fault that may occur.
It will be remembered that in 1808 Sir Humphry Davy constructed his battery
of 2,000 cells, and thus succeeded in exalting the tiny spark obtained in
closing the circuit into the luminous sheaf of the voltaic arc. He also
observed that the spark passed even when the poles were separated by a
distance varying from 1/40 to 1/30 of an inch. This appears to have been
subsequently forgotten, as we find later physicists questioning the
possibility of the spark leaping over any interpolar distance. Mr. J.
P. Gassiot, of Clapham, demonstrated the inaccuracy of this opinion by
constructing a battery of 3,000 Leclanche cells, which gave a spark of
0.025 inch; a similar number of "de la Rue" cells gives an 0.0564 inch
spark. This considerable increase in potential is chiefly due to better
insulation.
The great energy of this battery was illustrated by a variety of
experiments. Thus, a large condenser, specially constructed by Messrs.
Varley, and having a capacity equal to that of 6,485 large Leyden jars,
was almost immediately charged by the current from 10,000 cells. Wires of
various kinds, and from 9 inches to 29 inches in length, were instantly
volatilized by the passage of the electricity thus stored up. The current
induced in the secondary wire of a coil by the discharge of the condenser
through the primary, was also sufficiently intense to deflagrate wires of
considerable length and thickness.
It was with such power at his command that Dr. De la Rue proceeded to
investigate several important electrical laws. He has found, for example,
that the positive discharge is more intermittent than the negative,
that the arc is always preceded by a streamer-like discharge, that its
temperature is about 16,000 deg., and its length at the ordinary pressure
of the atmosphere, when taken between two points, varies as the square
of the number of cells. Thus, with a battery of 1,000 cells, the arc was
0.0051 inch, with 11,000 cells it increased to 0.62 inch. The same law was
found to hold when the discharge took place between a point and a disk; it
failed entirely, however, when the terminals were two disks.
It was also shown that the voltaic arc is not a phenomenon of conduction,
but is essentially a disruptive discharge, the intervals between the
passage of two successive static sparks being the time required for the
battery to collect sufficient power to leap over the interposed resistance.
This was further confirmed by the introduction of a condenser, when the
intervals were perceptibly larger.
Faraday proved that the quantity of electricity necessary to produce a
strong flash of lightning would result from the decomposition of a single
grain of water, and Dr. de la Rue's experiments confirm this extraordinary
statement. He has calculated that this quantity of electricity would be
5,000 times as great as the charge of his large condenser, and that a
lightning flash a mile long would require the potential of 3,500,000 cells,
that is to say, of 243 of his powerful batteries.
In experimenting with "vacuum" tubes, he has found that the discharge is
also invariably disruptive. This is an important point, as many physicists
speak and write of the phenomenon as one of conduction. Air, in every
degree of tenuity, refuses to act as a conductor of electricity. These
experiments show that the resistance of gaseous media diminishes with the
pressure only up to a certain point, beyond which it rapidly increases.
Thus, in the case of hydrogen, it diminishes up to 0.642 mm., 845
millionths; it then rises as the exhaustion proceeds, and at 0.00065 mm.,
8.6 millionths, it requires as high a potential as at 21.7 mm., 28.553
millionths. At 0.00137 mm., 1.8 millionth, the current from 11,000 cells
would not pass through a tube for which 430 cells sufficed at the pressure
of minimum resistance. At a pressure of 0.0055 mm., 0.066 millionth, the
highest exhaust obtained in any of the experiments, even a one-inch spark
from an induction coil refused to pass. It was also ascertained that there
is neither condensacian nor dilatation of the gas in contact with the
terminals prior to the passage of the discharge.
These researches naturally led to some speculation about the conditions
under which auroral phenomena may occur. Observers have variously stated
the height at which the aurora borealis attains its greatest brilliancy
as ranging between 124 and 281 miles. Dr. de la Rue's conclusions fix
the upper limit at 124 miles, and that of maximum display at 37 miles,
admitting also that the aurora may sometimes occur at an altitude of a few
thousand feet.
The aurora was beautifully illustrated by a very large tube, in which the
theoretical pressure was carefully maintained, the characteristic roseate
tinge being readily produced and maintained.
In studying the stratifications observed in vacuum tubes, Dr. de la Rue
finds that they originate at the positive pole, and that their steadiness
may be regulated by the resistance in circuit, and that even when the least
tremor cannot be detected by the eye, they are still produced by rapid
pulsations which may be as frequent as ten millions per second.
Dr. de la Rue concluded his interesting discourse by exhibiting some of the
finest tubes of his numerous and unsurpassed collection.--_Engineering_
* * * * *
MEASURING ELECTROMOTIVE FORCE.
Coulomb's torsion balance has been adapted by M. Baille to the measurement
of low electromotive forces in a very successful manner, and has been found
preferable by him to the delicate electrometers of Sir W. Thomson. It
is necessary to guard it from disturbances due to extraneous electric
influences and the trembling of the ground. These can be eliminated
completely by encircling the instrument in a metal case connected to
earth, and mounting it on solid pillars in a still place. Heat also has a
disturbing effect, and makes itself felt in the torsion of the fiber and
the cage surrounding the lever. These effects are warded off by inclosing
the instrument in a non-conducting jacket of wood shavings.
The apparatus of M. Baille consists of an annealed silver torsion wire of
2.70 meters long, and a lever 0.50 meter long, carrying at each extremity
a ball of copper, gilded, and three centimeters in diameter. Similar balls
are fixed at the corners of a square 20.5 meters in the side, and connected
in diagonal pairs by fine wire. The lever placed at equal distances from
the fixed balls communicates, by the medium of the torsion wire, with the
positive pole of a battery, P, the other pole being to earth.
Owing to some unaccountable variations in the change of the lever or
needle, M. Baille was obliged to measure the change at each observation.
This was done by joining the + pole of the battery to the needle, and one
pair of the fixed balls, and observing the deflection; then the deflection
produced by the other balls was observed. This operation was repeated
several times.
The battery, X, to be measured consisted of ten similar elements, and one
pole of it was connected to the fixed balls, while the other pole was
connected to the earth. The needle, of course, remained in contact with the
+ pole of the charging battery, P.
The deflections were read from a clear glass scale, placed at a distance
of 3.30 meters from the needle, and the results worked out from Coulomb's
static formula,
C a = (4 m m')/d squared, with
______________
/ sum((p/g) r squared)
O = / -------------
\/ C
[TEX: O = \sqrt{\frac{\sum \frac{p}{g} r^2}{C}}]
In M. Baillie's experiments, O = 437 cubed, and sum(pr squared)= 32171.6 (centimeter
grammes), the needle having been constructed of a geometrical form.
The following numbers represent the potential of an element of the
battery--that is to say, the quantity of electricity that the pole of that
battery spreads upon a sphere of one centimeter radius. They are expressed
in units of electricity, the unit being the quantity of electricity which,
acting upon a similar unit at a distance of one centimeter, produces a
repulsion equal to one gramme:
Volta pile 0.03415 open circuit.
Zinc, sulphate of copper, copper 0.02997 "
Zinc, acidulated water, copper, sulphate of copper 0.03709 "
Zinc, salt water, carbon peroxide of manganese 0.05282 "
Zinc, salt water, platinum, chloride of platinum 0.05027 "
Zinc, acidulated water, carbon nitric acid 0.06285 "
These results were obtained just upon charging the batteries, and are,
therefore, slightly higher than the potentials given after the batteries
became older. The sulphate of copper cells kept about their maximum value
longest, but they showed variations of about 10 per cent.
* * * * *
TELEPHONY BY THERMIC CURRENTS.
While in telephonic arrangements, based upon the principle of magnetic
induction, a relatively considerable expenditure of force is required in
order to set the tightly stretched membrane in vibration, in the so-called
carbon telephones only a very feeble impulse is required to produce the
differences in the current necessary for the transmission of sounds. In
order to produce relatively strong currents, even in case of sound-action
of a minimum strength, Franz Kroettlinger, of Vienna, has made an
interesting experiment to use thermo electric currents for the transmission
of sound to a distance. The apparatus which he has constructed is
exceedingly simple. A current of hot air flowing from below upward is
deflected more or less from its direction by the human voice. By its action
an adjacent thermo-battery is excited, whose current passes through the
spiral of an ordinary telephone, which serves as the receiving instrument.
As a source of heat the inventor uses a common stearine candle, the flame
of which is kept at one and the same level by means of a spring similar to
those used in carriage lamps. On one side of the candle is a sheet metal
voice funnel fixed upon a support, its mouth being covered with a movable
sliding disk, fitted with a suitable number of small apertures. On the
other side a similar support holds a funnel-shaped thermo-battery. The
single bars of metal forming this battery are very thin, and of such a
shape that they may cool as quickly as possible. Both the speaking-funnel
and the battery can be made to approach, at will, to the stream of warm air
rising up from the flame. The entire apparatus is inclosed in a tin case
in such a manner that only the aperture of the voice-funnel and the polar
clamps for securing the conducting wires appear on the outside. The inside
of the case is suitably stayed to prevent vibration. On speaking into the
mouth-piece of the funnel, the sound-waves occasion undulations in the
column of hot air which are communicated to the thermo-battery, and in this
manner corresponding differences are produced in the currents in the wires
leading to the receiving instrument.--_Oesterreichische-Ungarische Post._
* * * * *
THE TELECTROSCOPE.
By MONS. SENLECQ, of Ardres.
This apparatus, which is intended to transmit to a distance through a
telegraphic wire pictures taken on the plate of a camera, was invented in
the early part of 1877 by M. Senlecq, of Ardres. A description of the first
specification submitted by M. Senlecq to M. du Moncel, member of the
Paris Academy of Sciences, appeared in all the continental and American
scientific journals. Since then the apparatus has everywhere occupied the
attention of prominent electricians, who have striven to improve on it.
Among these we may mention MM. Ayrton, Perry, Sawyer (of New York),
Sargent (of Philadelphia), Brown (of London), Carey (of Boston), Tighe (of
Pittsburg), and Graham Bell himself. Some experimenters have used many
wires, bound together cable-wise, others one wire only. The result has
been, on the one hand, confusion of conductors beyond a certain distance,
with the absolute impossibility of obtaining perfect insulation; and,
on the other hand, an utter want of synchronism. The unequal and slow
sensitiveness of the selenium likewise obstructed the proper working of the
apparatus. Now, without a relative simplicity in the arrangement of the
conducting wires intended to convey to a distance the electric current with
its variations of intensity, without a perfect and rapid synchronism
acting concurrently with the luminous impressions, so as to insure the
simultaneous action of transmitter and receiver, without, in fine, an
increased sensitiveness in the selenium, the idea of the telectroscope
could not be realized. M. Senlecq has fortunately surmounted most of these
main obstacles, and we give to-day a description of the latest apparatus he
has contrived.
TRANSMITTER.
A brass plate, A, whereon the rays of light impinge inside a camera, in
their various forms and colors, from the external objects placed before the
lens, the said plate being coated with selenium on the side intended to
face the dark portion of the camera This brass plate has its entire surface
perforated with small holes as near to one another as practicable. These
holes are filled with selenium, heated, and then cooled very slowly, so as
to obtain the maximum sensitiveness. A small brass wire passes through the
selenium in each hole, without, however, touching the plate, on to the
rectangular and vertical ebonite plate, B, Fig. 1, from under this plate
at point, C. Thus, every wire passing through plate, A, has its point
of contact above the plate, B, lengthwise. With this view the wires are
clustered together when leaving the camera, and thence stretch to their
corresponding points of contact on plate, B, along line, C C. The surface
of brass, A, is in permanent contact with the positive pole of the battery
(selenium). On each side of plate, B, are let in two brass rails, D and E,
whereon the slide hereinafter described works.
[Illustration: Fig. 1]
Rail, E, communicates with the line wire intended to conduct the various
light and shade vibrations. Rail, D, is connected with the battery wire.
Along F are a number of points of contact corresponding with those along
C C. These contacts help to work the apparatus, and to insure the perfect
isochronism of the transmitter and receiver. These points of contact,
though insulated one from the other on the surface of the plate, are all
connected underneath with a wire coming from the positive pole of a special
battery. This apparatus requires two batteries, as, in fact, do all
autographic telegraphs--one for sending the current through the selenium,
and one for working the receiver, etc. The different features of this
important plate may, therefore, be summed up thus:
FIGURE 1.
D. Brass rail, grooved and connected with the line wire working the
receiver.
F. Contacts connected underneath with a wire permanently connected with
battery.
C. Contacts connected to insulated wires from selenium.
E. Brass rail, grooved, etc., like D.
RECEIVER.
A small slide, Fig. 2, having at one of its angles a very narrow piece of
brass, separated in the middle by an insulating surface, used for setting
the apparatus in rapid motion. This small slide has at the points, D D, a
small groove fitting into the brass rails of plate, B, Fig. 1, whereby it
can keep parallel on the two brass rails, D and E. Its insulator, B, Fig.
2, corresponds to the insulating interval between F and C, Fig. 1.
A, Fig. 3, circular disk, suspended vertically (made of ebonite or other
insulating material). This disk is fixed. All round the inside of its
circumference are contacts, connected underneath with the corresponding
wires of the receiving apparatus. The wires coming from the seleniumized
plate correspond symmetrically, one after the other, with the contacts of
transmitter. They are connected in the like order with those of disk, A,
and with those of receiver, so that the wire bearing the No. 5 from the
selenium will correspond identically with like contact No. 5 of receiver.
D, Fig. 4, gutta percha or vulcanite insulating plate, through which pass
numerous very fine platinum wires, each corresponding at its point of
contact with those on the circular disk, A.
The receptive plate must be smaller than the plate whereon the light
impinges. The design being thus reduced will be the more perfect from the
dots formed by the passing currents being closer together.
B, zinc or iron or brass plate connected to earth. It comes in contact with
chemically prepared paper, C, where the impression is to take place. It
contributes to the impression by its contact with the chemically prepared
paper.
In E, Fig. 3, at the center of the above described fixed plate is a
metallic axis with small handle. On this axis revolves brass wheel, F, Fig.
5.
[Illustration: FIG. 2]
On handle, E, presses continuously the spring, H, Fig. 3, bringing the
current coming from the selenium line. The cogged wheel in Fig. 5 has at a
certain point of its circumference the sliding spring, O, Fig. 5, intended
to slide as the wheel revolves over the different contacts of disk, A, Fig.
3.
This cogged wheel, Fig. 5, is turned, as in the dial telegraphs, by a rod
working in and out under the successive movements of the electro-magnet,
H, and of the counter spring. By means of this rod (which must be of a
non-metallic material, so as not to divert the motive current), and of an
elbow lever, this alternating movement is transmitted to a catch, G, which
works up and down between the cogs, and answers the same purpose as the
ordinary clock anchor.
[Illustration: FIG. 3]
This cogged wheel is worked by clockwork inclosed between two disks, and
would rotate continuously were it not for the catch, G, working in and out
of the cogs. Through this catch, G, the wheel is dependent on the movement
of electro-magnet. This cogged wheel is a double one, consisting of two
wheels coupled together, exactly similar one with the other, and so fixed
that the cogs of the one correspond with the void between the cogs of the
others. As the catch, G, moves down it frees a cog in first wheel, and both
wheels begin to turn, but the second wheel is immediately checked by catch,
G, and the movement ceases. A catch again works the two wheels, turn half a
cog, and so on. Each wheel contains as many cogs as there are contacts on
transmitter disk, consequently as many as on circular disk, A, Fig. 3, and
on brass disk within camera.
[Illustration: FIG. 4]
[Illustration: FIG. 5]
Having now described the several parts of the apparatus, let us see how it
works. All the contacts correspond one with the other, both on the side of
selenium current and that of the motive current. Let us suppose that the
slide of transmitter is on contact No. 10 for instance; the selenium
current starting from No. 10 reaches contact 10 of rectangular transmitter,
half the slide bearing on this point, as also on the parallel rail,
communicates the current to said rail, thence to line, from the line to
axis of cogged wheel, from axis to contact 10 of circular fixed disk,
and thence to contact 10 of receiver. At each selenium contact of the
rectangular disk there is a corresponding contact to the battery and
electro-magnet. Now, on reaching contact 10 the intermission of the current
has turned the wheel 10 cogs, and so brought the small contact, O, Fig. 5,
on No. 10 of the fixed circular disk.
As may be seen, the synchronism of the apparatus could not be obtained in
a more simple and complete mode--the rectangular transmitter being placed
vertically, and the slide being of a certain weight to its fall from the
first point of contact sufficient to carry it rapidly over the whole length
of this transmitter.
The picture is, therefore, reproduced almost instantaneously; indeed, by
using platinum wires on the receiver connected with the negative pole, by
the incandescence of these wires according to the different degrees of
electricity we can obtain a picture, of a fugitive kind, it is true, but
yet so vivid that the impression on the retina does not fade during the
relatively very brief space of time the slide occupies in traveling over
all the contacts. A Ruhmkorff coil may also be employed for obtaining
sparks in proportion to the current emitted. The apparatus is regulated
in precisely the same way as dial telegraphs, starting always from first
contact. The slide should, therefore, never be removed from the rectangular
disk, whereon it is held by the grooves in the brass rails, into which it
fits with but slight friction, without communicating any current to the
line wires when not placed on points of contact.
* * * * *
[Continued from SUPPLEMENT No. 274, page 4368.]
THE VARIOUS MODES OF TRANSMITTING POWER TO A DISTANCE.
[Footnote: A paper lately read before the Institution of Mechanical
Engineers.]
By ARTHUR ACHARD, of Geneva.
But allowing that the figure of 22 H. P., assumed for this power (the
result in calculating the work with compressed air being 19 H. P.) may be
somewhat incorrect, it is unlikely that this error can be so large that its
correction could reduce the efficiency below 80 per cent. Messrs. Sautter
and Lemonnier, who construct a number of compressors, on being consulted
by the author, have written to say that they always confined themselves in
estimating the power stored in the compressed air, and had never measured
the gross power expended. Compressed air in passing along the pipe, assumed
to be horizontal, which conveys it from the place of production to the
place where it is to be used, experiences by friction a diminution of
pressure, which represents a reduction in the mechanical power stored up,
and consequently a loss of efficiency.
The loss of pressure in question can only be calculated conveniently on the
hypothesis that it is very small, and the general formula,
p1 - p 4L
------- = ---- f(u),
[Delta] D
[TEX: \frac{p_1 - p}{\Delta} = \frac{4L}{D}f(u)]
is employed for the purpose, where D is the diameter of the pipe, assumed
to be uniform, L the length of the pipe, p1 the pressure at the entrance, p
the pressure at the farther end, u the velocity at which the compressed air
travels, [Delta] its specific weight, and f(u) the friction per unit of
length. In proportion as the air loses pressure its speed increases, while
its specific weight diminishes; but the variations in pressure are assumed
to be so small that u and [Delta] may be considered constant. As regards
the quantity f(u), or the friction per unit of length, the natural law
which regulates it is not known, audit can only be expressed by some
empirical formula, which, while according sufficiently nearly with the
facts, is suited for calculation. For this purpose the binomial formula, au
+ bu squared, or the simple formula, b1 u squared, is generally adopted; a b and b1 being
coefficients deduced from experiment. The values, however, which are to
be given to these coefficients are not constant, for they vary with the
diameter of the pipe, and in particular, contrary to formerly received
ideas, they vary according to its internal surface. The uncertainty in this
respect is so great that it is not worth while, with a view to accuracy, to
relinquish the great convenience which the simple formula, b1 u squared, offers.
It would be better from this point of view to endeavor, as has been
suggested, to render this formula more exact by the substitution of a
fractional power in the place of the square, rather than to go through
the long calculations necessitated by the use of the binomial au + bu squared.
Accordingly, making use of the formula b1 u squared, the above equation becomes,
p1 - p 4L
------- = ---- b1 u squared;
[Delta] D
[TEX: \frac{p_1 - p}{\Delta} = \frac{4L}{D} b_1 u^2]
or, introducing the discharge per second, Q, which is the usual figure
supplied, and which is connected with the velocity by the relation, Q =
([pi] D squared u)/4, we have
p1 - p 64 b1
------- = --------- L Q squared.
[Delta] [pi] squared D^5
[TEX: \frac{p_1 - p}{\Delta} = \frac{64 b_1}{\pi^2 D^5} L Q^2]
Generally the pressure, p1, at the entrance is known, and the pressure, p,
has to be found; it is then from p1 that the values of Q and [Delta] are
calculated. In experiments where p1 and p are measured directly, in order
to arrive at the value of the coefficient b1, Q and [Delta] would be
calculated for the mean pressure 1/2(p1 + p). The values given to the
coefficient b1 vary considerably, because, as stated above, it varies with
the diameter, and also with the nature of the material of the pipe. It
is generally admitted that it is independent of the pressure, and it is
probable that within certain limits of pressure this hypothesis is in
accordance with the truth.
D'Aubuisson gives for this case, in his _Traite d'Hydraulique_, a rather
complicated formula, containing a constant deduced from experiment, whose
value, according to a calculation made by the author, is approximately b1 =
0.0003. This constant was determined by taking the mean of experiments made
with tin tubes of 0.0235 meter (15/16 in.), 0.05 meter (2 in.), and 0.10
meter (4 in.) diameter; and it was erroneously assumed that it was correct
for all diameters and all substances.
M. Arson, engineer to the Paris Gas Company, published in 1867, in the
_Memoires de la Societe des Ingenieurs Civils de France_, the results of
some experiments on the loss of pressure in gas when passing through pipes.
He employed cast-iron pipes of the ordinary type. He has represented the
results of his experiments by the binomial formula, au + bu squared, and gives
values for the coefficients a and b, which diminish with an increase in
diameter, but would indicate greater losses of pressure than D'Aubuisson's
formula. M. Deviller, in his _Rapport sur les travaux de percement du
tunnel sous les Alpes_, states that the losses of pressure observed in the
air pipe at the Mont Cenis Tunnel confirm the correctness of D'Aubuisson's
formula; but his reasoning applies to too complicated a formula to be
absolutely convincing.
Quite recently M. E. Stockalper, engineer-in-chief at the northern end of
the St. Gothard Tunnel, has made some experiments on the air conduit of
this tunnel, the results of which he has kindly furnished to the author.
These lead to values for the coefficient b1 appreciably less than that
which is contained implicitly in D'Aubuisson's formula. As he experimented
on a rising pipe, it is necessary to introduce into the formula the
difference of level, h, between the two ends; it then becomes
p1 - p 64 b1
------- = --------- L Q squared + h.
[Delta] [pi] squared D^5
[TEX: \frac{p_1 - p}{\Delta} = \frac{64 b_1}{\pi^2 D^5} L Q^2 + h]
The following are the details of the experiments: First series of
experiments: Conduit consisting of cast or wrought iron pipes, joined by
means of flanges, bolts, and gutta percha rings. D = 0.20 m. (8 in.); L =
4,600 m. (15,100 ft,); h= 26.77 m. (87 ft. 10 in.). 1st experiment: Q =
0.1860 cubic meter (6.57 cubic feet), at a pressure of 1/2(p1 + p), and a
temperature of 22 deg. Cent. (72 deg. Fahr.); p1 = 5.60 atm., p =5.24 atm. Hence p1
- p = 0.36 atm.= 0.36 x 10,334 kilogrammes per square meter (2.116 lb. per
square foot), whence we obtain b1=0.0001697. D'Aubuisson's formula would
have given p1 - p = 0.626 atm.; and M. Arson's would have given p1 - p =
0.9316 atm. 2d experiment: Q = 0.1566 cubic meter (5.53 cubic feet), at a
pressure of 1/2(p1 + p), and a temperature of 22 deg. Cent. (72 deg. Fahr.); p1
= 4.35 atm., p = 4.13 atm. Hence p1 - p = 0.22 atm. = 0.22 X 10,334
kilogrammes per square meter (2,116 lb. per square foot); whence we obtain
b1 = 0.0001816. D'Aubuisson's formula would have given p1 - p = 0.347 atm;
and M. Arson's would have given p1 - p = 0.5382 atm. 3d experiment: Q =
0.1495 cubic meter (5.28 cubic feet) at a pressure of 1/2(p1 + p) and a
temperature 22 deg. Cent. (72 Fahr.); p1 = 3.84 atm., p = 3.65 atm. Hence p1 -
p = 0.19 atm. = 0.19 X 10,334 kilogrammes per square meter (2.116 lb. per
square foot); whence we obtain B1 = 0.0001966. D'Aubuisson's formula would
have given p1 - p = 0.284 atm., and M. Arson's would have given p1 - p =
0.4329 atm. Second series of experiments: Conduit composed of wrought-iron
pipes, with joints as in the first experiments. D = 0.15 meter (6 in.), L
- 0.522 meters (1,712 ft.), h = 3.04 meters (10 ft.) 1st experiments: Q =
0.2005 cubic meter (7.08 cubic feet), at a pressure of 1/2(p1 + p), and a
temperature of 26.5 deg. Cent. (80 deg. Fahr.); p1 = 5.24 atm., p = 5.00 atm. Hence
p1 - p = 0.24 atm. =0.24 x 10,334 kilogrammes per square meter (2,116 lb.
per square foot); whence we obtain b1 = 0.3002275. 2nd experiment: Q =
0.1586 cubic meter (5.6 cubic feet), at a pressure of 1/2(p1 + p), and a
temperature of 26.5 deg. Cent. (80 deg. Fahr.); p1 = 3.650 atm., p = 3.545 atm.
Hence p1 - p = 0.105 atm. = 0.105 x 10,334 kilogrammes per square meter
(2,116 lb. per square foot); whence we obtain b1 = 0.0002255. It is clear
that these experiments give very small values for the coefficient. The
divergence from the results which D'Aubuisson's formula would give is due
to the fact that his formula was determined with very small pipes. It is
probable that the coefficients corresponding to diameters of 0.15 meter
(6 in.) and 0.20 meter (8 in.) for a substance as smooth as tin, would be
still smaller respectively than the figures obtained above.
The divergence from the results obtained by M. Arson's formula does not
arise from a difference in size, as this is taken into account. The author
considers that it may be attributed to the fact that the pipes for the St.
Gothard Tunnel were cast with much greater care than ordinary pipes, which
rendered their surface smoother, and also to the fact that flanged joints
produce much less irregularity in the internal surface than the ordinary
spigot and faucet joints.
Lastly, the difference in the methods of observation and the errors which
belong to them, must be taken into account. M. Stockalper, who experimented
on great pressures, used metallic gauges, which are instruments on whose
sensibility and correctness complete reliance cannot be placed; and
moreover the standard manometer with which they were compared was one of
the same kind. The author is not of opinion that the divergence is owing to
the fact that M. Stockalper made his observations on an air conduit, where
the pressure was much higher than in gas pipes. Indeed, it may be assumed
that gases and liquids act in the same manner; and, as will be [1]
explained later on, there is reason to believe that with the latter a rise
of pressure increases the losses of pressure instead of diminishing them.
[Transcribers note 1: corrected from 'as will we explained']
All the pipes for supplying compressed air in tunnels and in headings of
mines are left uncovered, and have flanged joints; which are advantages not
merely as regards prevention of leakage, but also for facility of laying
and of inspection. If a compressed air pipe had to be buried in the ground
the flanged joint would lose a part of its advantages; but, nevertheless,
the author considers that it would still be preferable to the ordinary
joint.
It only remains to refer to the motors fed with the compressed air.
This subject is still in its infancy from a practical point of view. In
proportion as the air becomes hot by compression, so it cools by expansion,
if the vessel containing it is impermeable to heat. Under these conditions
it gives out in expanding a power appreciably less than if it retained its
original temperature; besides which the fall of temperature may impede the
working of the machine by freezing the vapor of water contained in the air.
If it is desired to utilize to the utmost the force stored up in the
compressed air it is necessary to endeavor to supply heat to the air during
expansion so as to keep its temperature constant. It would be possible
to attain this object by the same means which prevent heating from
compression, namely, by the circulation and injection of water. It would
perhaps be necessary to employ a little larger quantity of water for
injection, as the water, instead of acting by virtue both of its heat of
vaporization and of its specific heat, can in this case act only by virtue
of the latter. These methods might be employed without difficulty for air
machines of some size. It would be more difficult to apply them to small
household machines, in which simplicity is an essential element; and we
must rest satisfied with imperfect methods, such as proximity to a stove,
or the immersion of the cylinder in a tank of water. Consequently loss of
power by cooling and by incomplete expansion cannot be avoided. The only
way to diminish the relative amount of this loss is to employ compressed
air at a pressure not exceeding three or four atmospheres.
The only real practical advance made in this matter is M. Mekarski's
compressed air engine for tramways. In this engine the air is made to pass
through a small boiler containing water at a temperature of about 120 deg.
Cent. (248 deg. Fahr.), before entering the cylinder of the engine. It must
be observed that in order to reduce the size of the reservoirs, which
are carried on the locomotive, the air inside them must be very highly
compressed; and that in going from the reservoir into the cylinder it
passes through a reducing valve or expander, which keeps the pressure of
admission at a definite figure, so that the locomotive can continue working
so long as the supply of air contained in the reservoir has not come down
to this limiting pressure. The air does not pass the expander until after
it has gone through the boiler already mentioned. Therefore, if the
temperature which it assumes in the boiler is 100 deg. Cent. (212 deg. Fahr.), and
if the limiting pressure is 5 atm., the gas which enters the engine will be
a mixture of air and water vapor at 100 deg. Cent.; and of its total pressure
the vapor of water will contribute I atm. and the air 4 atm. Thus this
contrivance, by a small expenditure of fuel, enables the air to act
expansively without injurious cooling, and even reduces the consumption of
compressed air to an extent which compensates for part of the loss of power
arising from the preliminary expansion which the air experiences before its
admission into the engine. It is clear that this same contrivance, or what
amounts to the same thing, a direct injection of steam, at a sufficient
pressure, for the purpose of maintaining the expanding air at a constant
temperature, might be tried in a fixed engine worked by compressed air with
some chance of success.
Whatever method is adopted it would be advantageous that the losses of
pressure in the pipes connecting the compressors with the motors should be
reduced as much as possible, for in this case that loss would represent
a loss of efficiency. If, on the other hand, owing to defective means of
reheating, it is necessary to remain satisfied with a small amount of
expansion, the loss of pressure in the pipe is unimportant, and has only
the effect of transferring the limited expansion to a point a little lower
on the scale of pressures. If W is the net disposable force on the shaft
of the engine which works the compressor, v1 the volume of air at the
compressor, p1. given by the compressor, and at the temperature of the
surrounding air, and p0 the atmospheric pressure, the efficiency of the
compressor, assuming the air to expand according to Boyle's law, is given
by the well-known formula--
p1 v1 log (p1 / p0)
-------------------.
W
[TEX: \frac{p_1 v_1 \log \frac{p_1}{p_0}}{W}]
Let p2 be the value to which the pressure is reduced by the loss of
pressure at the end of the conduit, and v2 the volume which the air
occupies at this pressure and at the same temperature; the force stored
up in the air at the end of its course through the conduit is p2 v2
log(p2/p0); consequently, the efficiency of the conduit is
p2 v2 log(p2/p0)
----------------
p1 v1 log(p1/p0)
[TEX: \frac{p_2 v_2 \log\frac{p_2}{p_0}}{p_2 v_2 \log\frac{p_2}{p_0}}]
a fraction that may be reduced to the simple form
log(p2/p0)
----------,
log(p1/p0)
[TEX: \frac{\log\frac{p_2}{p_0}}{\log\frac{p_2}{p_0}}]
if there is no leakage during the passage of the air, because in that cause
p2 v2 = p1 v1. Lastly, if W1 is the net disposable force on the shaft of
the compressed air motor, the efficiency of this engine will be,
W1
----------------
p2 v2 log(p2/p0)
[TEX: \frac{W_1}{p_2 v_2 \log \frac{p_2}{p_0}}]
and the product of these three partial efficiencies is equal to W1/W, the
general efficiency of the transmission.
III. _Transmission by Pressure Water_.--As transmission of power by
compressed air has been specially applied to the driving of tunnels, so
transmission by pressure water has been specially resorted to for lifting
heavy loads, or for work of a similar nature, such as the operations
connected with the manufacture of Bessemer steel or of cast-iron pipes.
The author does not propose to treat of transmissions established for this
special purpose, and depending on the use of accumulators at high pressure,
as he has no fresh matter to impart on this subject, and as he believes
that the remarkable invention of Sir William Armstrong was described for
the first time, in the "Proceedings of the Institution of Mechanical
Engineers." His object is to refer to transmissions applicable to general
purposes.
The transmission of power by water may occur in another form. The motive
force to be transmitted may be employed for working pumps which raise the
water, not to a fictitious height in an accumulator, but to a real height
in a reservoir, with a channel from this reservoir to distribute the water
so raised among several motors arranged for utilizing the pressure. The
author is not aware that works have been carried out for this purpose.
However, in many towns a part of the water from the public mains serves to
supply small motors--consequently, if the water, instead of being brought
by a natural fall, has been previously lifted artificially, it might be
said that a transmission of power is here grafted on to the ordinary
distribution of water.
Unless a positive or negative force of gravity is introduced into the
problem, independently of the force to be transmitted, the receivers of
the water pressure must be assumed to be at the same level as the forcing
pumps, or more correctly, the water discharged from the receivers to be at
the same level as the surface of the water from which the pumps draw their
supply. In this case the general efficiency of transmission is the product
of three partial efficiencies, which correspond exactly to those mentioned
with regard to compressed air. The height of lift, contained in the
numerator of the fraction which expresses the efficiency of the pumps, is
not to be taken as the difference in level between the surface of the water
in the reservoir and the surface of the water whence the pumps draw their
supply; but as this difference in level, plus the loss of pressure in the
suction pipe, which is usually very short, and plus the loss in the channel
to the reservoir, which may be very long. A similar loss of initial
pressure affects the efficiency of the discharge channel. The reservoir, if
of sufficient capacity, may become an important store of power, while the
compressed air reservoir can only do so to a very limited extent.
Omitting the subject of the pumps, and passing on at once to the discharge
main, the author may first point out that the distinction between the
ascending and descending mains of the system is of no importance, for two
reasons: first, that nothing prevents the motors being supplied direct from
the first alone; and second, that the one is not always distinct from the
other. In fact, the reservoir may be connected by a single branch pipe with
the system which goes from the pumps to the motors; it may even be placed
at the extreme end of this system beyond the motors, provided always that
the supply pipe is taken into it at the bottom. The same formula may be
adopted for the loss of initial pressure in water pipes as for compressed
air pipes, viz.,
p1 - p 64 b1
------- = --------- L Q squared +- h;
[Delta] [pi] squared D^5
[TEX: \frac{p_1 - p}{\Delta} = \frac{64 b_1}{\pi^2 D^5} L Q^2 \pm h]
h being the difference of level between the two ends of the portion of
conduit of length, L, and the sign + or - being used according as the
conduit rises or falls. The specific weight, [delta], is constant, and the
quotients, p1/[delta] and p/[delta], represent the heights, z and z1, to
which the water could rise above the pipes, in vertical tubes branching
from it, at the beginning and end of the transit. The values assigned to
the coefficient b1 in France, are those determined by D'Arcy. For new
cast-iron pipes he gives b1 - 0.0002535 + 1/D 0.000000647; and recommends
that this value should be doubled, to allow for the rust and incrustation
which more or less form inside the pipes during use. The determination of
this coefficient has been made from experiments where the pressure has
not exceeded four atmospheres; within these limits the value of the
coefficient, as is generally admitted, is independent of the pressure. The
experiments made by M. Barret, on the pressure pipes of the accumulator at
the Marseilles docks, seem to indicate that the loss of pressure would be
greater for high pressures, everything else being equal. This pipe, having
a diameter of 0.127 m. (5 in.), was subjected to an initial pressure of 52
atmospheres. The author gives below the results obtained for a straight
length 320 m. (1050 ft) long; and has placed beside them the results which
D'Arcy's formula would give.
Loss of head, in meters or ft. respectively
per 100 meters or ft. run of pipes.
+-----------------^-------------------+
| |
Calculated loss.
+-----------^-----------+
| |
Velocity of flow Actual loss
per second. observed. Old pipes. New pipes.
Meters. Feet. Met. or Ft. Met. or Ft. Met. or Ft.
0.25 0.82 1.5 0.12 0.06
0.50 1.64 2.5 0.48 0.24
0.75 2.46 3.7 1.08 0.54
1.00 3.28 5.5 1.92 0.96
1.25 4.10 6.1 3.00 1.50
1.50 4.92 7.3 4.32 2.16
1.75 5.74 8.0 5.88 2.94
2.00 6.56 10.2 7.68 3.84
2.25 7.38 11.7 9.72 4.86
2.50 8.20 14.0 12.00 6.00
Moreover, these results would appear to indicate a different law from that
which is expressed by the formula b1 u squared, as is easy to see by representing
them graphically. It would be very desirable that fresh experiments should
be made on water pipes at high pressure, and of various diameters. Of
machines worked by water pressure the author proposes to refer only to two
which appear to him in every respect the most practical and advantageous.
One is the piston machine of M. Albert Schmid, engineer at Zurich. The
cylinder is oscillating, and the distribution is effected, without an
eccentric, by the relative motion of two spherical surfaces fitted one
against the other, and having the axis of oscillation for a common axis.
The convex surface, which is movable and forms part of the cylinder, serves
as a port face, and has two ports in it communicating with the two ends of
the cylinder. The concave surface, which is fixed and plays the part of a
slide valve, contains three openings, the two outer ones serving to admit
the pressure water, and the middle one to discharge the water after it has
exerted its pressure. The piston has no packing. Its surface of contact has
two circumferential grooves, which produce a sort of water packing acting
by adhesion. A small air chamber is connected with the inlet pipe, and
serves to deaden the shocks. This engine is often made with two cylinders,
having their cranks at right angles.
The other engine, which is much less used, is a turbine on Girard's system,
with a horizontal axis and partial admission, exactly resembling in
miniature those which work in the hydraulic factory of St. Maur, near
Paris. The water is introduced by means of a distributer, which is fitted
in the interior of the turbine chamber, and occupies a certain portion
of its circumference. This turbine has a lower efficiency than Schmid's
machine, and is less suitable for high pressures; but it possesses this
advantage over it, that by regulating the amount of opening of the
distributer, and consequently the quantity of water admitted, the force can
be altered without altering the velocity of rotation. As it admits of great
speeds, it could be usefully employed direct, without the interposition of
spur wheels or belts for driving magneto-electric machines employed for the
production of light, for electrotyping, etc.
In compressed air machines the losses of pressure due to incomplete
expansion, cooling, and waste spaces, play an important part. In water
pressure machines loss does not occur from these causes, on account of the
incompressibility of the liquid, but the frictions of the parts are the
principal causes of loss of power. It would be advisable to ascertain
whether, as regards this point, high or low pressures are the most
advantageous. Theoretical considerations would lead the author to imagine
that for a piston machine low pressures are preferable. In conclusion, the
following table gives the efficiencies of a Girard turbine, constructed by
Messrs. Escher Wyss & Co., of Zurich, and of a Schmid machine, as measured
by Professor Fliegnor, in 1871:
ESCHER WYSS & CO'S TURBINE.
Effective Head of Water. Revolutions Efficiency.
per minute.
Meters. Feet. Revs. Per cent.
20.7 67.9 628 68.5
20.7 67.9 847 47.4
24.1 79.0 645 68.5
27.6 90.5 612 65.7
27.6 90.5 756 68.0
31.0 101.7 935 56.9
31.0 101.7 1,130 35.1
SCHMID MOTOR.
8.3 27.2 226 37.4
11.4 37.4 182 67.4
14.5 47.6 254 53.4
17.9 58.7 157 86.2
20.7 67.9 166 89.6
20.7 67.9 225 74.6
24.1 79.0 238 76.7
24.1 79.0 389 64.0
27.6 90.5 207 83.9
It will be observed that these experiments relate to low pressures; it
would be desirable to extend them to higher pressures.
IV. _Transmission by Electricity._--However high the efficiency of an
electric motor may be, in relation to the chemical work of the electric
battery which feeds it, force generated by an electric battery is too
expensive, on account of the nature of the materials consumed, for a
machine of this kind ever to be employed for industrial purposes. If,
however, the electric current, instead of being developed by chemical
work in a battery, is produced by ordinary mechanical power in a
magneto-electric or dynamo-electric machine, the case is different; and
the double transformation, first of the mechanical force into an electric
current, and then of that current into mechanical force, furnishes a means
for effecting the conveyance of the power to a distance.
It is this last method of transmission which remains to be discussed. The
author, however, feels himself obliged to restrict himself in this matter
to a mere summary; and, indeed, it is English physicists and engineers who
have taken the technology of electricity out of the region of empiricism
and have placed it on a scientific and rational basis. Moreover, they are
also taking the lead in the progress which is being accomplished in this
branch of knowledge, and are best qualified to determine its true bearings.
When an electric current, with an intensity, i, is produced, either by
chemical or mechanical work, in a circuit having a total resistance, R, a
quantity of heat is developed in the circuit, and this heat is the exact
equivalent of the force expended, so long as the current is not made use of
for doing any external work. The expression for this quantity of heat, per
unit of time, is Ai squaredR; A being the thermal equivalent of the unit of power
corresponding to the units of current and resistance, in which i and R are
respectively expressed. The product, i squaredR, is a certain quantity of power,
which the author proposes to call _power transformed into electricity_.
When mechanical power is employed for producing a current by means of
a magneto-electric or dynamo-electric machine--or, to use a better
expression, by means of a _mechanical generator of electricity_--it is
necessary in reality to expend a greater quantity of power than i squaredR in
order to make up for losses which result either from ordinary friction
or from certain electro magnetic reactions which occur. The ratio of the
quantity, i squaredR, to the power, W, actually expended per unit of time is
called the efficiency of the generator. Designating it by K, we obtain, W
= i squaredR/K. It is very important to ascertain the value of this efficiency,
considering that it necessarily enters as a factor into the evaluation of
all the effects to be produced by help of the generator in question. The
following table gives the results of certain experiments made early in
1879, with a Gramme machine, by an able physicist, M Hagenbach, Professor
at the University at Basle, and kindly furnished by him to the author:
Revolutions per minute 935 919.5 900.5 893
Total resistance in Siemens' units 2.55 3.82 4.94 6.06
Total resistance in absolute units 2.435 3.648 4.718 5.787
x10^9 x10^9 x10^9 x10^9
Intensity in chemical units 17.67 10.99 8.09 6.28
Intensity in absolute units 2.828 1.759 1.295 1.005
Work done i squaredR in absolute units 1948.6 1129.2 791.3 584.9
x10^7 x10^7 x10^7 x10^7
Work done i squaredR in kilogrammes 198.6 115.1 80.66 59.62
Power expended in kilogrammes 301.5 141.0 86.25 83.25
Efficiency, per cent. 65.9 81.6 93.5 71.6
M. Hagenbach's dynamometric measurements were made by the aid of a brake.
After each experiment on the electric machine, he applied the brake to the
engine which he employed, taking care to make it run at precisely the same
speed, with the same pressure of steam, and with the same expansion as
during experiment. It would certainly be better to measure the force
expended during and not after the experiment, by means of a registering
dynamometer. Moreover, M. Hagenbach writes that his measurements by means
of the brake were very much prejudiced by external circumstances; doubtless
this is the reason of the divergences between the results obtained.
About the same time Dr. Hopkinson communicated to this institution the
results of some very careful experiments made on a Siemens machine. He
measured the force expended by means of a registering dynamometer, and
obtained very high coefficients of efficiency, amounting to nearly 90 per
cent. M. Hagenbach also obtained from one machine a result only a little
less than unity. Mechanical generators of electricity are certainly
capable of being improved in several respects, especially as regards their
adaptation to certain definite classes of work. But there appears to
remain hardly any margin for further progress as regards efficiency. Force
transformed into electricity in a generator may be expressed by i [omega] M
C; [omega] being the angular velocity of rotation; M the magnetism of one
of the poles, inducing or induced, which intervenes; and C a constant
specially belonging to each apparatus, and which is independent of
the units adopted. This constant could not be determined except by
an integration practically impossible; and the product, M C, must be
considered indivisible. Even in a magneto-electric machine (with permanent
inducing magnets), and much more in a dynamo-electric machine (inducing by
means of electro-magnets excited by the very current produced) the product,
M C, is a function of the intensity. From the identity of the expressions,
i squaredR and i [omega] M C we obtain the relation M C = IR/[omega] which
indicates the course to be pursued to determine experimentally the law
which connects the variations of M C with those of i. Some experiments made
in 1876, by M. Hagenbach, on a Gramme dynamo-electric machine, appear to
indicate that the magnetism, M C, does not increase indefinitely with the
intensity, but that there is some maximum value for this quantity. If,
instead of working a generator by an external motive force, a current is
passed through its circuit in a certain given direction, the movable part
of the machine will begin to turn in an opposite direction to that in which
it would have been necessary to turn it in order to obtain a current in the
aforesaid direction. In virtue of this motion the electro-magnetic forces
which are generated may be used to overcome a resisting force. The machine
will then work as a motor or receiver. Let i be the intensity of the
external current which works the motor, when the motor is kept at rest. If
it is now allowed to move, its motion produces, in virtue of the laws of
induction, a current in the circuit of intensity, i1, in the opposite
direction to the external current; the effective intensity of the current
traversing the circuit is thus reduced to i - i1. The intensity of the
counter current is given, like that of the generating current, by the
equation, i1 squaredR = i1 [omega]1 M1 C1, or i1R = [omega]1 M1 C1, the index, 1,
denoting the quantities relating to the motor. Here M1 C1 is a function of
i - i1, not of i. As in a generator the force transformed into electricity
has a value, i [omega] M C, so in a motor the force developed by
electricity is (i - i1) [omega]1 M1 C1. On account, however, of the losses
which occur, the effective power, that is the disposable power on the shaft
of the motor, will have a smaller value, and in order to arrive at it a
coefficient of efficiency, K1, must be added. We shall then have W1 = K1
(i-i1) [omega]1 M1 C1. The author has no knowledge of any experiments
having been made for obtaining this efficiency, K1. Next let us suppose
that the current feeding the motor is furnished by a generator, so that
actual transmission by electricity is taking place. The circuit, whose
resistance is R, comprises the coils, both fixed and movable, of the
generator and motor, and of the conductors which connect them. The
intensity of the current which traverses the circuit had the value, i, when
the motor was at rest; by the working of the motor it is reduced to i - i1.
The power applied to the generator is itself reduced to W-[(i-i1)[omega]
M C]/K. The prime mover is relieved by the action of the counter current,
precisely as the consumption of zinc in the battery would be reduced by the
same cause, if the battery was the source of the current. The efficiency
of the transmission is W1/W. Calculation shows that it is expressed by the
following equations:W1/W = K K1 [([omega]11 M1 C1)/([omega]1 M C)], or = K
K1 [([omega]11 M1 C)/([omega]11 M1 C1 + (i-i1) R)]; expressions in which
it must be remembered M C and M1 C1 are really functions of (i-i1). This
efficiency is, then, the product of three distinct factors, each evidently
less than unity, namely, the efficiency belonging to the generator, the
efficiency belonging to the motor, and a third factor depending on the rate
of rotation of the motor and the resistance of the circuit. The influence
which these elements exert on the value of the third factor cannot be
estimated, unless the law is first known according to which the magnetisms,
M C, M1 C C1, vary with the intensity of the current.
GENERAL RESULTS.
Casting a retrospective glance at the four methods of transmission of power
which have been examined, it would appear that transmission by ropes forms
a class by itself, while the three other methods combine into a natural
group, because they possess a character in common of the greatest
importance. It may be said that all three involve a temporary
transformation of the mechanical power to be utilized into potential
energy. Also in each of these methods the efficiency of transmission is
the product of three factors or partial efficiencies, which correspond
exactly--namely, first, the efficiency of the instrument which converts
the actual energy of the prime mover into potential energy; second, the
efficiency of the instrument which reconverts this potential energy into
actual energy, that is, into motion, and delivers it up in this shape
for the actual operations which accomplish industrial work; third, the
efficiency of the intermediate agency which serves for the conveyance of
potential energy from the first instrument to the second.
This last factor has just been given for transmission by electricity. It
is the exact correlative of the efficiency of the pipe in the case of
compressed air or of pressure water. It is as useful in the case of
electric transmission, as of any other method, to be able, in studying the
system, to estimate beforehand what results it is able to furnish, and for
this purpose it is necessary to calculate exactly the factors which compose
the efficiency.
In order to obtain this desirable knowledge, the author considers that the
three following points should form the aim of experimentalists: First,
the determination of the efficiency, K, of the principal kinds of
magneto-electric, or dynamo-electric machines working as generators;
second, the determination of the efficiency, K1, of the same machines
working as motors; third, the determination of the law according to which
the magnetism of the cores of these machines varies with the intensity of
the current. The author is of opinion that experiments made with these
objects in view would be more useful than those conducted for determining
the general efficiency of transmission, for the latter give results only
available under precisely similar conditions. However, it is clear that
they have their value and must not be neglected.
There are, moreover, many other questions requiring to be elucidated by
experiment, especially as regards the arrangement of the conducting wires:
but it is needless to dwell further upon this subject, which has been ably
treated by many English men of science--for instance, Dr. Siemens and
Professor Ayrton. Nevertheless, for further information the author would
refer to the able articles published at Paris, by M. Mascart, in the
_Journal de Physique_, in 1877 and 1878. The author would gladly have
concluded this paper with a comparison of the efficiencies of the four
systems which have been examined, or what amounts to the same thing--with a
comparison of the losses of power which they occasion. Unfortunately, such
a comparison has never been made experimentally, because hitherto the
opportunity of doing it in a demonstrative manner has been wanting, for the
transmission of power to a distance belongs rather to the future than to
the present time. Transmission by electricity is still in its infancy; it
has only been applied on a small scale and experimentally.
Of the three other systems, transmission by means of ropes is the only one
that has been employed for general industrial purposes, while compressed
air and water under pressure have been applied only to special purposes,
and their use has been due much more to their special suitableness for
these purposes than from any considerations relative to loss of power.
Thus the effective work of the compressed air used in driving the
tunnels through the Alps, assuming its determination to be possible, was
undoubtedly very low; nevertheless, in the present state of our appliances
it is the only process by which such operations can be accomplished. The
author believes that transmission by ropes furnishes the highest proportion
of useful work, but that as regards a wide distribution of the transmitted
power the other two methods, by air and water, might merit a preference.
* * * * *
THE HOTCHKISS REVOLVING GUN.
The Hotchkiss revolving gun, already adopted in the French navy and by
other leading European nations, has been ordered for use in the German navy
by the following decree of the German Emperor, dated January 11 last: "On
the report made to me, I approve the adoption of the Hotchkiss revolving
cannon as a part of the artillery of my navy; and each of my ships,
according to their classification, shall in general be armed with this
weapon in such a manner that every point surrounding the vessel may be
protected by the fire of at least two guns at a minimum range of 200
meters."
* * * * *
THALLIUM PAPERS AS OZONOMETERS.
Schoene has given the results of an extended series of experiments on the
use of thallium paper for estimating approximately the oxidizing material
in the atmosphere, whether it be hydrogen peroxide alone, or mixed with
ozone, or perhaps also with other constituents hitherto unknown. The
objection to Schoenbein's ozonometer (potassium iodide on starch paper) and
to Houzeau's ozonometer (potassium iodide on red litmus paper) lies in
the fact that their materials are hygroscopic, and their indications vary
widely with the moisture of the air. Since dry ozone does not act on these
papers, they must be moistened; and then the amount of moisture varies the
result quite as much as the amount of ozone. Indeed, attention has been
called to the larger amount of ozone near salt works and waterfalls, and
the erroneous opinion advanced that ozone is formed when water is finely
divided. And Boettger has stated that ozone is formed when ether is
atomized; the fact being that the reaction he observed was due to the
H_2O_2 always present in ether. Direct experiments with the Schoenbein
ozonometer and the psychrometer gave parallel curves; whence the author
regards the former as only a crude hygrometer. These objections do not lie
against the thallium paper, the oxidation to brown oxide by either ozone or
hydrogen peroxide not requiring the presence of moisture, and the color,
therefore, being independent of the hygrometric state of the air. Moreover,
when well cared for, the papers undergo no farther change of color and may
be preserved indefinitely. The author prepares the thallium paper a few
days before use, by dipping strips of Swedish filtering paper in a solution
of thallous hydrate, and drying. The solution is prepared by pouring a
solution of thallous sulphate into a boiling solution of barium hydrate,
equivalent quantities being taken, the resulting solution of thallous
hydrate being concentrated in vacuo until 100 c.c. contains 10 grammes
Tl(OH). For use the strips are hung in the free air in a close vessel,
preferably over caustic lime, for twelve hours. Other papers are used, made
with a two per cent. solution. These are exposed for thirty-six hours. The
coloration is determined by comparison with a scale having eleven degrees
of intensity upon it. Compared with Schoenbein's ozonometer, the results are
in general directly opposite. The thallium papers show that the greatest
effect is in the daytime, the iodide papers that it is at night. Yearly
curves show that the former generally indicate a rise when the latter give
a fall. The iodide curve follows closely that of relative humidity, clouds,
and rain; the thallium curve stands in no relation to it. A table of
results for the year 1879 is given in monthly means, of the two thallium
papers, the ozonometer, the relative humidity, cloudiness, rain, and
velocity of wind.--_G. F. B., in Ber. Berl. Chem. Ces._
* * * * *
THE AUDIPHONE IN ENGLAND.
The audiphone has been recently tried in the Board School for Deaf and
Dumb at Turin street, Bethnal Green, with very satisfactory results--so
satisfactory that the report will recommend its adoption in the four
schools which the London Board have erected for the education of the deaf
and dumb. Some 20 per cent. of the pupils in deaf and dumb schools have
sufficient power of hearing when assisted by the audiphone to enable them
to take their places in the classes of the ordinary schools.
* * * * *
CONDUCTIVITY OF MOIST AIR.
Many physical treatises still assert that moist air conducts electricity,
though Silberman and others have proved the contrary. An interesting
experiment bearing on this has been described lately by Prof. Marangoni.
Over a flame is heated some water in a glass jar, through the stopper of
which passes a bent tube to bell-jar (held obliquely), which thus gets
filled with aqueous vapor. The upper half of a thin Leyden jar charged is
brought into the bell-jar, and held there four or five seconds; it is
then found entirely discharged. That the real cause of this, however, is
condensation of the vapor on the part of the glass that is not coated with
tin foil (the liquid layer acting by conduction) can be proved; for if that
part of the jar be passed several times rapidly through the flame, so as
to heat it to near 100 deg. C., before inserting in the bell-jar, a different
effect will be had; the Leyden jar will give out long sparks after
withdrawal. This is because the glass being heated no longer condenses the
vapor on its surface, and there is no superficial conduction, as in the
previous case.
* * * * *
FLOATING PONTOON DOCK.
Considerable attention has been given for some years past to the subject of
floating pontoon docks by Mr. Robert Turnbull, naval architect, of South
Shields, Eng., who has devised the ingenious arrangement which forms the
subject of the annexed illustration. The end aimed at and now achieved by
Mr. Turnbull was so to construct floating docks or pontoons that they may
rise and fall in a berth, and be swung round at one end upon a center post
or cylinder--nautically known as a dolphin--projecting from the ground at
a slight distance from the berth. The cylinder is in deep water, and,
when the pontoon is swung and sunk to the desired depth by letting in the
necessary amount of water, a vessel can be floated in and then secured. The
pontoon, with the vessel on it, is then raised by pumping out the contained
water until she is a little above the level of the berth. The whole is then
swung round over the berth, the vessel then being high and dry to enable
repairs or other operations to be conducted. For this purpose, one end of
the pontoon is so formed as to enable it to fit around the cylinder, and
to be held to it as to a center or fulcrum, about which the pontoon can be
swung. The pontoon is of special construction, and has air-chambers at the
sides placed near the center, so as to balance it. It also has chambers at
the ends, which are divided horizontally in order that the operation of
submerging within a berth or in shallow water may be conducted without
risk, the upper chambers being afterwards supplied with water to sink the
pontoon to the full depth before a vessel is hauled in. When the ship is in
place, the pontoon with her is then lifted above the level of the berth in
which it has to be placed, and then swung round into the berth. In some
cases, the pontoon is provided with a cradle, so that, when in berth, the
vessel on the cradle can be hauled up a slip with rails arranged as
a continuation of the cradle-rails of the pontoon, which can be then
furnished with another cradle, and another vessel lifted.
It is this latter arrangement which forms the subject of our illustration,
the vessel represented being of the following dimensions: Length between
perpendiculars, 350 feet; breadth, moulded, 40 feet; depth, moulded, 32
feet; tons, B. M., 2,600; tons net, 2,000. At A, in fig. 1, is shown in
dotted lines a portion of the vessel and pontoon, the ship having just been
hauled in and centered over the keel blocks. At B, is shown the pontoon
with the ship raised and swung round on to a low level quay. Going a step
further in the operation, we see at C, the vessel hauled on to the slipways
on the high-level quay. In this case the cylinder is arranged so that
the vessel may be delivered on to the rails or slips, which are arranged
radially, taking the cylinder as the center. There may be any number of
slips so arranged, and one pontoon may be made available for several
cylinders at the deep water parts of neighboring repairing or building
yards, in which case the recessed portion of the pontoon, when arranged
around the cylinder, has stays or retaining bars fitted to prevent it
leaving the cylinder when the swinging is taking place, such as might
happen in a tideway.
[Illustration: Fig. 1. IMPROVED FLOATING PONTOON DRY DOCK.]
The arrangements for delivering vessels on radial slips is seen in plan at
fig. 2, where A represents the river or deep water; B is the pontoon with
the vessel; C being the cylinder or turning center; D is the low-level
quay on to which the pontoon carrying the ship is first swung; E is the
high-level quay with the slip-ways; F is an engine running on rails around
the radial slips for drawing the vessels with the cradle off the pontoon,
and hauling them up on to the high-level quay; and G shows the repairing
shops, stores, and sheds. A pontoon attached to a cylinder may be fitted
with an ordinary wet dock; and then the pontoon, before or after the vessel
is upon it, can be slewed round to suit the slips up which the vessel has
to be moved, supposing the slips are arranged radially. In this case, the
pivot end of the pontoon would be a fixture, so to speak, to the cylinder.
The pontoon may also be made available for lifting heavy weights, by
fitting a pair of compound levers or other apparatus at one end, the
lifting power being in the pontoon itself. In some cases, in order to
lengthen the pontoon, twenty-five or fifty foot lengths are added at
the after end. When not thus engaged, those lengths form short pontoons
suitable for small vessels.--_Iron_.
* * * * *
WEIRLEIGH, BRENCHLEY, KENT.
Some few years since, Mr. Harrison Weir (whose drawings of natural history
are known probably to a wider circle of the general public than the works
of most artists), wishing to pursue his favorite study of animals and
horticulture, erected on the steep hillside of the road leading from
Paddock Wood to Brenchley, a small "cottage ornee" with detached studio.
Afterward desiring more accommodation, he carried out the buildings shown
in our illustrations. Advantage has been taken of the slope of the hill on
one side, and the rising ground in the rear on the other, to increase the
effect of the buildings and meet the difficulty of the levels. The two
portions--old, etched, and new, shown as black--are connected together by a
handsome staircase, which is carried up in the tower, and affords access to
the various levels. The materials are red brick, with Bathstone dressings,
and weather-tiling on the upper floors. Black walnut, pitch pine, and
sequoias have been used in the staircase, and joiner's work to the
principal rooms. The principal stoves are of Godstone stone only, no iron
or metal work being used. The architects are Messrs. Wadmore & Baker, of 35
Great St. Helens, E.C.; the builders, Messrs. Penn Brothers, of Pembury,
Kent.--_Building News_.
[Illustration: ARTISTS HOMES NO 11 "WEIRLEIGH" BRENCHLEY, KENT. THE
RESIDENCE OF HARRISON WEIR ESQ'RE WADMORE & BAKER ARCHITECTS]
* * * * *
RAPID BREATHING AS A PAIN OBTUNDER IN MINOR SURGERY, OBSTETRICS, THE
GENERAL PRACTICE OF MEDICINE AND OF DENTISTRY.
[Footnote: Read before the Philadelphia County Medical Society, May 12,
1880, by W. G. A. Bonwill, M.D., D.D.S., Philadelphia.]
Through the kind invitation of your directors, I am present to give you
the history of "rapid breathing" as an analgesic agent, as well as my
experience therein since I first discovered it. It is with no little
feeling of modesty that I appear before such a learned and honorable
body of physicians and surgeons, and I accept the privilege as a high
compliment. I trust the same liberal spirit which prompted you to call this
subject to the light of investigation will not forsake you when you have
heard all I have to say and you sit in judgment thereon. Sufficient time
has now elapsed since the first promulgation of the subject for the shafts
of ridicule to be well nigh spent (which is the common logic used to crush
out all new ideas), and it is to be expected that gentlemen will look upon
it with all the charity of a learned body, and not be too hasty to condemn
what they have had but little chance to investigate; and, of course, have
not practiced with that success which can only come from an intelligent
understanding of its application and _modus operandi_.
Knowing the history of past discoveries, I was well prepared for the
crucible. I could not hope to be an exception. But, so far, the medical
profession have extended me more favor than I have received at the hands of
the dental profession.
My first conception of the analgesic property of a pain obtunder in
contradistinction to its anaesthetic effect, which finally led to the
discovery of the inhalation of common air by "rapid breathing," was in 1855
or 1856, while performing upon my own teeth certain operations which gave
me intense pain (and I could not afford to hurt myself) without a resort to
ether and chloroform. These agents had been known so short a time that no
one was specially familiar with their action. Without knowing whether I
could take chloroform administered by myself, and at the same time perform
with skill the excavation of extremely sensitive dentine or tooth-bone, as
if no anaesthetic had been taken, and not be conscious of pain, was more
than the experience of medical men at that time could assure me. But,
having a love for investigation of the unknown, I prepared myself for the
ordeal. By degrees I took the chloroform until I began to feel very plainly
its primary effects, and knowing that I must soon be unconscious, I applied
the excavator to the carious tooth, and, to my surprise, found no pain
whatever, but the sense of touch and hearing were marvelously intensified.
The small cavity seemed as large as a half bushel; the excavator more the
size of an ax; and the sound was equally magnified. That I might not be
mistaken, I repeated the operation until I was confident that anaesthetics
possessed a power not hitherto known--that of analgesia. To be doubly
certain, I gave it in my practice, in many cases with the same happy
results, which saved me from the risks incident to the secondary effects of
anaesthetics, and which answered for all the purposes of extracting from
one to four teeth. Not satisfied with any advance longer than I could find
a better plan, I experimented with the galvanic current (to and fro) by so
applying the poles that I substituted a stronger impression by electricity
from the nerve centers or ganglia to the peripheries than was made from the
periphery to the brain. This was so much of a success that I threw
aside chloroform and ether in removing the living nerve of a tooth with
instruments instead of using arsenic; and for excavating sensitive caries
in teeth, preparatory to filling, as well as many teeth extracted by it.
But this was short-lived, for it led to another step. Sometimes I would
inflict severe pain in cases of congested pulps or from its hasty
application, or pushing it to do too much, when my patient invariably would
draw or inhale the breath _very forcibly and rapidly_. I was struck with
the repeated coincidence, and was led to exclaim: "Nature's anaesthetic."
This then reminded me of boyhood's bruises. The involuntary action of every
one who has a finger hurt is to place it to the mouth and draw violently in
the air and hold it for an instant, and again repeat it until the pain is
subdued. The same action of the lungs occurs, except more powerfully,
in young children who take to crying when hurt. It will be noticed they
breathe very rapidly while furiously crying, which soon allays the
irritation, and sleep comes as the sequel. Witness also when one is
suddenly startled, how violently the breath is taken, which gives relief.
The same thing occurs in the lower animals when pain is being inflicted at
the hand of man.
This was advance No. 3, and so sure was I of this new discovery, that I at
once made an application while removing decay from an extremely sensitive
tooth. To be successful, I found I must make the patient take the start,
and I would follow with a thrust from the excavator, which move would be
accomplished before the lungs could be inflated. This was repeated for
at least a minute, until the operation was completed, I always following
immediately or synchronously with the inhalation.
This led to step No. 4, which resulted in its application to the extracting
of teeth and other operations in minor surgery.
Up to this time I had believed the sole effect of the rapid inhalation was
due to mere diversion of the will, and this was the only way nature could
so violently exert herself--that of controlling the involuntary action of
the lungs to her uses by the _safety valve_, or the voluntary movement.
The constant breathing of the patient for thirty seconds to a minute left
him in a condition of body and mind resembling the effects of ether and
chloroform in their primary stages. I could but argue that the prolonged
breathing each time had done it; and, if so, then there must be some
specific effect over and above the mere diversion by the will. To what
could it be due? To the air alone, which went in excess into the lungs in
the course of a minute! Why did I not then immediately grasp the idea of
its broader application as now claimed for it? It was too much, gentlemen,
for that hour. Enough had been done in this fourth step of conception to
rest in the womb of time, until by evolution a higher step could be made at
the maturity of the child. Being self-satisfied with my own baby, I watched
and caressed it until it could take care of itself, and my mind was again
free for another conception.
The births at first seemed to come at very short intervals; but see how
long it was between the fourth and the fifth birth. It was soon after that
my mind became involved in inventions--a hereditary outgrowth--and the
electric mallet and then the dental engine, the parent of your surgical
engine, to be found in the principal hospitals of this city, took such
possession of my whole soul, that my air analgesic was left slumbering. It
was not until August, 1875--nineteen years after--that it again came up in
full force, without any previous warning.
This time it was no law of association that revived it; but it seemed
the whispering of some one in the air--some ethereal spirit, if you
please--which instituted it, and advanced the following problem: "Nitrous
oxide gas is composed of the same elements as ordinary air, with a larger
equivalent of oxygen, except it is a chemical compound, not a mechanical
mixture, and its anaesthetic effects are said to be due to the excess of
oxygen. If this be a fact, then why can you not produce a similar effect by
rapid breathing for a minute, more or less, by which a larger quantity of
oxygen is presented in the lungs for absorption by the blood?"
This query was soon answered by asking myself another: "If the rapid
inhalation of air into the lungs does not increase the heart's action and
cause it to drive the blood in exact ratio to the inhalations, then _I can_
produce partial anaesthesia from this excess of oxygen brought about by the
voluntary movements over their ordinary involuntary action of the lungs."
The next question was: Will my heart be affected by this excess of air in
the lungs to such an extent that there will be a full reciprocity between
them? Without making any trial of it, I argued that, while there is no
other muscular movement than that of the chest as under the control of the
will, and as nature has given to the will the perfect control over the
lungs to supply more or less air, as is demanded by the pneumogastric nerve
for the immediate wants of the economy, when the _involuntary action_ is
not sufficient; and the heart not being under the control of the will, and
its action never accelerated or diminished except by a specific poison, or
from the general activity of the person in violent running or working, the
blood is forced into the heart faster and must get rid of it, when a larger
supply of oxygen is demanded and rapid breathing must occur, or asphyxia
result. I was not long in deciding that the heart _would not be
accelerated_ but a trifle--say a tenth--and, under the circumstances, I
said: "The air _is_ an anaesthetic."
From this rapid course of argument, I was so profoundly convinced of its
truth, that without having first tried it upon my own person, I would have
sat where I was, upon the curbstone, and had a tooth removed with the
perfect expectation of absence of pain and of still being conscious of
touch. While yet walking with my children, I commenced to breathe as
rapidly as possible, and, as anticipated, found my steps growing shorter
and shorter, until I came to a stand, showing to my mind clearly that my
argument in advance was right, so far as locomotion was concerned; and,
upon referring to my pulse, I found but little acceleration.
To what other conclusion could I arrive from this argument, with the
foundation laid nineteen years before, when I established on my own person
by experiment the fact of analgesia as induced from chloroform, with the
many experiments in rapid respiration on tooth bone?
From this moment until its first application to the extraction of a tooth
you can well imagine my suspense. That I might not fail in the very first
attempt, I compelled myself and others in my household to breathe rapidly
to investigate the phenomenon. This gave me some idea as to the proper
method of proceeding in its administering.
The first case soon appeared, and was a perfect success, going far beyond
my anticipations, for the effect was such as to produce a partial paralysis
of the hands and arms to the elbow. Again and again I tried it in every
case of extraction and many other experiments, doubting my own senses for
a long time at a result so anomalous and paradoxical. I was reminded just
here of a phenomenon which gave me additional proof--that of blowing a
dull fire to revive it. For a minute or so one blows and blows in rapid
succession until, rising from the effort, a sense of giddiness for a
few moments so overcomes that the upright position is with difficulty
maintained. In this condition you are fitted for having a tooth extracted
or an abscess lanced.
Believing that I had something new to offer which might be of use to
suffering humanity, I read the first article upon it Nov. 17, 1875, before
the Franklin Institute. Shortly after I was invited before the Northern
Medical Society of this city to address them thereon. A number of medical
gentlemen have been using it in their practice, while the bulk of them have
spurned it as "negative" and preposterous, without an effort at trying it,
which I can _now_ very well understand.
Unless one is aware of the fact that in the use of any agent which has the
power to suspend the volition, it can be taken to that point where he is
still conscious of _touch and hearing_, and at the same time not cognizant
of pain inflicted, the action of rapid breathing could not be understood.
And I regret to say that of three-fourths of the medical men I have talked
with on the subject they had not been aware of such a possibility from
ether and chloroform. Until this analgesic state could be established in
their minds it was impossible to convince them that the excess of oxygen,
as obtained by rapid breathing, could be made to produce a similar effect.
_I_ should have been as reluctant as any one to believe it, had I not
personally experienced the effect while performing an operation which would
otherwise have been very painful. Such a result could not well be reached
by any course of reasoning.
Has it proven in my practice what has been claimed for it--a substitute
for the powerful anaesthetics in minor operations in surgery? Most
emphatically, yes! So completely has it fulfilled its humble mission in
my office, that I can safely assert there has not been more than five per
cent. of failures. I have given it under all circumstances of diseased
organs, and have seen no other than the happiest results in its after
effects. It may well be asked just here: Why has it not been more generally
and widely used by the dental profession as well as the medical, if it is
really what is claimed for it? The most satisfactory and charitable answer
to be given is, the failure upon their part to comprehend the _fact_ as
existing in chloroform and ether that there is such a state as analgesia;
or, in other words, that the animal economy is so organized, while the
sense of touch is not destroyed, but rather increased, the mind of the
subject fails to perceive a sense of pain when anaesthetics are given, and
the effects are manifested in the primary stage. As I before intimated,
such is the knowledge possessed by most of those who administer ether and
chloroform. This was enough to cause nearly every one to look upon it as a
bubble or air castle. Many gentlemen told me they tried it upon themselves,
and, while it affected them very seriously by giddiness, they still
_retained consciousness_; and, such being the case, no effect could be
produced for obtunding pain. Others told me they were afraid to continue
the breathing alarmed at the vertigo induced. And the practitioner who has
adopted it more effectively than any other laughed at me when I first told
him of the discovery; but his intimate association with me changed his
views after much explanation and argument between us.
It was hardly to be expected that without this knowledge of analgesia,
and without any explanation from me as to the _modus operandi_ of rapid
breathing, other than a few suggestions or directions as to how the effect
was induced, even the most liberal of medical men should be able to make
it effective, or have the least disposition to give it a preliminary trial
upon themselves, and, of course, would not attempt it upon a patient.
Notwithstanding, it found a few adherents, but only among my personal
_medical_ friends, with whom I had an opportunity to explain what I
believed its physiological action, and the cases of success in my own
practice. To this I have submitted as among the inevitable in the calendar
of discoveries of all grades.
My own profession have attempted to _ridicule_ it out of its birthright
and possible existence, which style of argument is not resorted to by true
logicians.
To all this I can truly say I have not for one moment faltered. I could
afford to wait. The liberality of this society alone fully compensates for
the seeming indisposition of the past, believing that it is proper that
every advance should be confronted, and, if in time found worthy, give it
God speed.
From its first conception I have diligently labored to solve its _modus
operandi_, and the doubt in my own mind as to whether I could be mistaken
in my observations. I asked the opinion of our best chemical teachers if
air could have such effect. One attributed it to oxygen stimulation, and
the other to nitrogen. Another gentleman told me the medical profession had
come to the conclusion that it was possible for me to thus extract teeth,
but it was due solely to my strong _personal magnetism_ (which power I was
not before aware I possessed).
Now, from what I have related of the successive and natural steps which
finally culminated in this process or plan of analgesia induced by an
excess of ordinary air taken forcibly into the lungs above what is
necessary for life, and from what I shall state as to the apparently
anomalous or paradoxical effects, with its physiological action, and the
simple tests made upon each of my patients, I shall trust to so convince
you of its plausibility and possibility that it will be made use of in
hundreds of minor operations where ether and chloroform are now used.
Aside from my assertion and that of its friends, that the effects can be
produced by air alone, you must have some light shed upon the causes of its
physiological action, which will appeal to your _medical_ reason.
To assign an action to any drug is difficult, and in the cases of ether and
the other anaesthetics a quarter of a century still finds many conflicting
opinions. This being true, you will deal leniently with me for the opinion
I hold as to their analgesic action. Of course it will be objected to,
for the unseen is, to a great extent, unknowable. Enough for my argument,
however; it seems to suit the case very well without looking for another;
and while it was based on the phenomenon resulting from many trials, and
not the trials upon it as a previous theory, I shall be content with it
until a better one can be found.
What is it I claim as a new discovery, and the facts and its philosophy?
I have asserted that I can produce, from rapidly breathing common air at
the rate of a hundred respirations a minute, a similar effect to that from
ether, chloroform, and nitrous oxide gas, in their primary stages; and I
can in this way render patients sufficiently insensible to acute pain from
any operation where the time consumed is not over twenty to thirty seconds.
While the special senses are in partial action, the sense of pain is
obtunded, and in many cases completely annulled, consciousness and general
sensibility being preserved.
To accomplish this, each patient must be instructed how to act and what to
expect. As simple as it may seem, there is a proper and consistent plan to
enable you to reach full success. Before the patient commences to inhale he
is informed of the fact that, while he will be unconscious of pain, he
will know full, or partially well, every touch upon the person; that the
inhalation must be vigorously kept up during the whole operation without
for an instant stopping; that the more energetically and steadily he
breathes, the more perfect the effect, and that if he cease breathing
during the operation, pain will be felt. Fully impress them with this
idea, for the very good reason that they may stop when in the midst of an
operation, and the fullest effects be lost. It is obligatory to do so on
account of its evanescent effects, which demand that the patient be pushed
by the operator's own energetic appeals to "go on." It is very difficult
for any person to respire more than one hundred times to the minute, as he
will become by that time so exhausted as not to be able to breathe at all,
as is evidenced by all who have thus followed my directions. For the next
minute following the completion of the operation the subject will not
breathe more than once or twice. Very few have force enough left to raise
hand or foot. The voluntary muscles have nearly all been subjugated and
overcome by the undue effort at forced inhalation of one hundred over
seventeen, the normal standard. It will be more fully understood further on
in my argument why I force patients, and am constantly speaking to them to
go on.
I further claim that for the past four years, so satisfactory has been the
result of this system in the extracting of teeth and deadening extremely
sensitive dentine, there was no longer any necessity for chloroform,
ether, or nitrous oxide in the dental office. That such teeth as cannot be
extracted by its aid can well be preserved and made useful, except in a
very few cases, who will not be forced to breathe.
The anaesthetics, when used in major operations, where time is needed for
the operation, can be made more effective by a lesser quantity when given
in conjunction with "rapid breathing." Drs. Garrettson and Hews, who have
thus tried it, tell me it takes one-half to three-fourths less, and the
after effects are far less nauseating and unpleasant.
As an agent in labor where an anaesthetic is indicated, it is claimed by
one who has employed it (Dr. Hews) in nearly every case for three years, he
has used "rapid breathing" solely, and to the exclusion of chloroform and
ether. For this I have his assertion, and have no doubt of it whatever, for
if any agent could break down the action of the voluntary muscles of the
parts involved, which prevent the involuntary muscles of the uterus from
having their fullest effect, it is this. The very act of rapid breathing so
affects the muscles of the abdomen as to force the contents of the uterus
downward or outward, while the specific effect of the air at the end of a
minute's breathing leaves the subject in a semi-prostrate condition, giving
the uterus full chance to act in the interim, because free of the will to
make any attempt at withholding the involuntary muscles of the uterus from
doing their natural work. It is self evident; and in this agent we claim
here a boon of inestimable value. And not least in such cases is, there is
no danger of hemorrhage, since the cause of the effect is soon removed.
In attestation of many cases where it has been tried, I have asked the
mother, and, in some cases, the attendants, whether anything else had been
given, and whether the time was very materially lessened, there has been
but one response, and that in its favor.
Gentlemen, if we are not mistaken in this, you will agree with me in saying
that it is no mean thing, and should be investigated by intelligent men and
reported upon. From my own knowledge of its effects in my practice, I am
bound to believe this gentleman's record.
I further claim for it a special application in dislocations. It has
certainly peculiar merits here, as the will is so nearly subjugated by
it as to render the patient quite powerless to resist your effort at
replacing, and at the same time the pain is subdued.
It is not necessary I should further continue special applications; when
its _modus operandi_ is understood, its adaptation to many contingencies
will of a sequence follow.
It is well just here, before passing to the next point of consideration, to
answer a query which may arise at this juncture:
What are the successive stages of effects upon the economy from its
commencement until the full effect is observed, and what proof have I that
it was due to the amount of air inhaled?
The heart's action is not increased more than from seventy (the average) to
eighty and sometimes ninety, but is much enfeebled, or throwing a lesser
quantity of blood. The face becomes suffused, as in blowing a fire or in
stooping, which continues until the breathing is suspended, when the
face becomes paler. (Have not noticed any purple as from asphyxia by a
deprivation of oxygen.) The vision becomes darkened, and a giddiness soon
appears. The voluntary muscles furthest from the heart seem first to be
affected, and the feet and hands, particularly the latter, have a numbness
at their ends, which increases, until in many cases there is partial
paralysis as far as the elbow, while the limbs become fixed. The hands are
so thoroughly affected that, when open, the patient is powerless to close
them and _vice versa_. There is a vacant gaze from the eyes and looking
into space without blinking of the eyelids for a half minute or more. The
head seems incapable of being held erect, and there is no movement of the
arms or legs as is usual when in great pain. There is no disposition on the
part of the patient to take hold of the operator's hand or interfere with
the operation.
Many go on breathing mechanically after the tooth is removed, as if nothing
had occurred. Some are aware that the tooth has been extracted, and say
they felt it; others could not tell what had been accomplished. The
majority of cases have an idea of what is being done, but are powerless to
resist.
With the very intelligent, or those who stop to reason, I have to teach
them the peculiarities of being sensible of touch and not of pain.
One very interesting case I will state. In extracting seven teeth for a
lady who was very _unwilling_ to believe my statement as to touch and no
pain, I first removed three teeth after having inhaled for one minute, and
when fully herself, she stated that she could not understand why there was
no pain while she was conscious of each one extracted; it was preposterous
to believe such an effect could be possible, as her reason told her that
there is connected with tooth extracting pain in the part, and of severe
character, admitting, though, she felt no pain. She allowed one to be
removed without anything, and she could easily distinguish the change, and
exclaimed, "It is all the difference imaginable!" When the other three were
extracted, there was perfect success again as with the first three.
One of the most marked proofs of the effects of rapid breathing was that of
a boy of eleven years of age for whom I had to extract the upper and lower
first permanent molars on each side. He breathed for nearly a minute, when
I removed in about twenty seconds all four of the teeth, without a moment's
intermission or the stopping the vigorous breathing; and not a murmur,
sigh, or tear afterward.
He declared there was no pain, and we needed no such assertion, for there
was not the first manifestation from him that he was undergoing such a
severe operation.
Another case, the same day, when I had to extract the superior wisdom teeth
on both sides for an intelligent young lady of eighteen years, where I had
to use two pairs of forceps on each tooth (equivalent to extraction of four
teeth), and she was so profoundly affected afterward that she could; not
tell me what had been done other than that I had touched her four times.
She was overcome from its effects for at least a minute afterward. She was
delighted.
With such severe tests I fear very little the result in any case I can have
them do as I bid.
There can be no mistake that there is a _specific action_ from something.
It cannot be personal magnetism or mesmeric influence exerted by me, for
such cases are rare, averaging about 10 per cent, only of all classes.
Besides, in mesmeric influence the time has nothing to do with it; whereas,
in my cases, it cannot last over a half minute or minute at most. It cannot
be fear, as such cases are generally more apt to get hurt the worse. It is
not diversion of mind alone, as we have an effect above it.
There is no better way of testing whether pain has been felt than by taking
the lacerated or contused gums of the patient between the index finger
and thumb and making a gentle pressure to collapse the alveolar borders;
invariably, they will cry out lustily, _that is pain_! This gives undoubted
proof of a specific agent. There is no attempt upon my _own_ part to exert
any influence over my patients in any way other than that they shall
believe what I say in regard to _giving_ them _no pain_ and in the
following of my orders. Any one who knows how persons become mesmerized can
attest that it was not the _operator who forces them under it against
their will_, but it is a peculiar state into which any one who has within
themselves this temperament can _place_ themselves where any one who knows
how can have control. It is not the will of the operator. I therefore
dismiss this as unworthy of consideration in connection with rapid
breathing.
Then you may now ask, To what do I attribute this very singular phenomenon?
Any one who followed, in the earlier part of this paper, the course of
the argument in my soliloquy, after twenty years had elapsed from my
observation upon myself of the analgesic effects of chloroform, can almost
give something of an answer.
That you may the more easily grasp what I shall say, I will ask you, If it
be possible for any human being to make one hundred inhalations in a minute
and the heart's action is not increased more than ten or twenty pulsations
over the normal, what should be the effect upon the brain and nerve
centers?
If the function of oxygen in common air is to set free in the blood,
either in the capillaries alone, or throughout the whole of the arterial
circulation, carbonic acid gas; and that it cannot escape from the system
unless it do so in the lungs as it passes in the general current--except
a trace that is removed by the skin and kidneys--and that the quantity of
carbonic acid gas set free is in exact relation to the amount of oxygen
taken into the blood, what effect _must be_ manifested where one hundred
respirations in one minute are made--five or six times the normal
number--while the heart is only propelling the blood a very little faster
through the lungs, and _more feebly_--say 90 pulsations at most, when to
be in proportion it should be 400 to 100 respirations to sustain life any
length of time?
You cannot deny the fact that a definite amount of oxygen can be absorbed
and is absorbed as fast as it is carried into the lungs, even if there be
one hundred respirations to the minute, while the pulsations of the heart
are only ninety! Nature has _made it_ possible to breathe so rapidly to
meet any emergency; and we can well see its beautiful application in the
normal action of both the heart and lungs while one is violently running.
What would result, and that very speedily, were the act of respiration to
remain at the standard--say 18 or 20--when the heart is in violent action
from this running? Asphyxia would surely end the matter! And why? The
excessive exercise of the whole body is setting free from the tissues such
an amount of excretive matter, and carbon more largely than all the others,
that, without a relative action of the lungs to admit the air that oxygen
may be absorbed, carbonic acid gas cannot be liberated through the lungs
as fast as the waste carbon of the overworked tissues is being made by
disassimilation from this excess of respiration.
You are already aware how small a quantity of carbonic acid in excess in
the air will seriously affect life. Even 2 to 3 per cent, in a short time
will prove fatal. In ordinary respiration of 20 to the minute the average
of carbonic acid exhaled is 4.35.
From experiments long ago made by Vierordt--see Carpenter, p. 524--you will
see the relative per cent, of carbonic acid exhaled from a given number of
respirations. When he was breathing six times per minute, 5.5 per cent of
the exhaled air was carbonic acid; twelve times, 4.2; twenty-four times,
3.3; forty-eight times, 3; ninety-six times, 2.6.
Remember this is based upon the whole number of respirations in the minute
and not each exhalation--which latter could not be measured by the most
minute method.
Let us deduct the minimum amount, 2.6 per cent, of carbonic acid when
breathing ninety-six times per minute, from the average, at twenty per
minute, or the normal standard, which is recorded in Carpenter, p. 524, as
4.35 per minute, and we have retained in the circulation nearly 2 per cent.
of carbonic acid; that, at the average, would have passed off through the
lungs without any obstruction, and life equalized; but it not having been
thrown off as fast as it should have been, must, of necessity, be left to
prey upon the brain and nerve centers; and as 2 to 3 per cent., we are
told, will so poison the blood, life is imperiled and that speedily.
It is not necessary we should argue the point as to whether oxygen
displaces carbonic acid in the tissues proper or the capillaries. The
theory of Lavoisier on this point has been accepted.
We know furthermore, as more positive, that tissues placed in an atmosphere
of oxygen will set free carbonic acid, and that carbonic acid has a
paralyzing effect upon the human hand held in it for a short time. The
direct and speedy effects of this acid upon the delicate nervous element of
the brain is so well known that it must be accepted as law. One of the most
marked effects is the suspension of locomotion of the legs and arms,
and the direct loss of will power which must supervene before voluntary
muscular inactivity, which amounts to partial paralysis in the hands or
feet, or peripheral extremities of the same.
Now that we have sufficient evidence from the authorities that carbonic
acid can be retained in the blood by excessive breathing, and enough to
seriously affect the brain, and what its effects are when taken directly
into the lungs in excess, we can enter upon what I have held as the most
reasonable theory of the phenomenon produced by rapid breathing for
analgesic purposes; which _theory_ was not _first_ conceived and the
process made to yield to it, but the phenomenon was long observed, and
from the repetition of the effects and their close relationship to that
of carbonic acid on the economy, with the many experiments performed
upon myself, I am convinced that what I shall now state will be found to
substantiate my discovery. Should it not be found to coincide with what
some may say is physiological truth, it will not invalidate the discovery
itself; for of that I am far more positive than Harvey was of the discovery
of the circulation of the blood; or of Galileo of the spherical shape of
the earth. And I ask that it shall not be judged by my theory, but from the
practice.
It should have as much chance for investigation as the theory of
Julius Robert Mayer, upon which he founded, or which gave rise to the
establishment of one of the most important scientific truths--"the
conservation of energy," and finally the "correlation of forces," which
theory I am not quite sure was correct, although it was accepted, and as
yet, I have not seen it questioned.
In all due respect to him I quote it from the sketch of that remarkable
man, as given in the _Popular Science Monthly_, as specially bearing on my
discovery:
"Mayer observed while living in Java, that the _venous blood_ of some of
his patients had a singularly bright red color. The observation riveted
his attention; he reasoned upon it, and came to the conclusion that the
brightness of the color was due to the fact that a less amount of oxidation
was sufficient to keep up the temperature of the body in a hot climate than
a cold one. The darkness of the venous blood he regarded as the visible
sign of the energy of the oxidation."
My observation leads me to the contrary, that the higher the temperature
the more rapid the breathing to get clear of the excess of carbon, and
hence more oxygenation of the blood which will arterialize the venous
blood, unless there is a large amount of carbonized matter from the tissues
to be taken up.
Nor must it be denied because of the reasoning as presented to my mind by
some outside influence in my soliloquy when I first exclaimed, "Nature's
anaesthetic," where the argument as to the effects of nitrous oxide gas
being due to an excess of oxygen was urged, and that common air breathed in
excess would do the same thing.
I am not sure that _it_ was correct, for the effects of nitrous oxide is,
perhaps, due to a deprivation of mechanically mixed air.
Knowing what I do of theory and practice, I can say with assurance that
there is not a medical practitioner who would long ponder in any urgent
case as to the thousand and one theories of the action of remedies; but
would resort to the _practical_ experience of others and his own finally.
(What surgeon ever stops to ask how narcotics effect their influence?)
After nearly thirty years of association with ether and chloroform, who can
positively answer as to their _modus operandi?_ It is thus with nearly the
whole domain of medicine. It is not yet, by far, among the sciences, with
immutable laws, such as we have in chemistry. Experimentation is giving us
more specific knowledge, and "practice alone has tended to make perfect."
(Then, gentlemen will not set at naught my assertion and practical results.
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