Scientific American Supplement, No. 288
by
Various
Part 2 out of 3
products which unite energetically with bromine, and which are converted
into resinous polymers of ordinary sulphuric acid. It is difficult to
isolate, by means of fractional distillation, definite products with
constant boiling points.
* * * * *
NOTES ON CANANGA OIL OR ILANG-ILANG OIL.
[Footnote: From the _Archiv der Pharmacie_.]
By F. A. FLUeCKIGER.
This oil, on account of its fragrance, which is described by most
observers as extremely pleasant, has attained to some importance, so
that it appears to me not superfluous to submit the following remarks
upon it and the plant from which it is derived.
The tree, of which the flowers yield the oil known under the name
"Ilang-ilang" or "Alanguilan," is the _Cananga odorata_, Hook. fil. et
Thomp.,[1] of the order Unonaceae, for which reason it is called also in
many price lists "Oleum Anonae," or "Oleum Unonae" It is not known to
me whether the tree can be identified in the old Indian and Chinese
literature.[2] In the west it was first named by Ray as "Arbor
Saguisan," the name by which it was called at that time at Lucon[3]
Rump[4] gave a detailed description of the "Bonga Cananga," as the
Malays designate the tree ("Tsjampa" among the Javanese); Rumph's
figure, however is defective. Further, Lamarck[5] has short notices of
it under "Canang odorant, _Uvaria odorata_." According to Roxburgh,[6]
the plant was in 1797 brought from Sumatra to the Botanical Gardens in
Calcutta. Dunal devoted to the _Ucaria odorata_, or, properly, _Unona
odorata_, as he himself corrected it, a somewhat more thorough
description in his "Monographic de la Famille des Anonacees,"[7] which
principally repeats Rumph's statements.
[Footnote 1: "Flora Indica," i (1855), 130.]
[Footnote 2: "No mention of any plant or flowers, which might be
identified with Cananga, can be traced in any Sanskrit works."--Dr.
Charles Rice, _New Remedies_, April, 1881, page 98.]
[Footnote 3: Ray. "Historia Plantarum, Supplementum," tomi i et ii
"Hist. Stirpium Insulae Luzonensis et Philippinarum" a Georgio Josepho
Canello; London, 1704, 83]
[Footnote 4: "Herbarium Amboinense, Amboinsch Kruidboek," ii.
(Amsterdam, 1750), cap. xix, fol. 195 and tab. 65.]
[Footnote 5: "Encyclopedie methodique. Botanique," i (1783), 595.]
[Footnote 6: "Flora Indica," ii. (Serampore, 1832), 661.]
[Footnote 7: Paris, 1817, p. 108, 105.]
Lastly, we owe a very handsome figure of the _Cananga odorata_ to the
magnificent "Flora Javae," of Blume;[1] a copy of this, which in the
original is beautifully colored, is appended to the present notice. That
this figure is correct I venture to assume after having seen numerous
specimens in Geneva, with De Candolle, as well as in the Delessert
herbarium. The unjustifiable name _Unona odoratissima_, which
incorrectly enough has passed into many writings, originated with
Blanco,[2] who in his description of the powerful fragrance of the
flowers, which in a closed sleeping room produces headache, was induced
to use the superlative "odoratissima." Baillon[3] designated as
Canangium the section of the genus _Uvaria_, from which he would not
separate the Ilang-ilang tree.
[Footnote 1: Vol. i. (Brussels, 1829), fol. 29, tab ix et xiv. B.]
[Footnote 2: "Flora de Filipinas," Manila, 1845, 325. _Unona
odoratissima_, Alang-ilan. The latter name, according to Sonnerat, is
stated by the Lamarck to be of Chinese origin; Herr Reymann derives it
from the Tagal language.]
[Footnote 3: "Dictionnaire de Botanique."]
[Illustration: CANAGA ODORATA]
The notice of Maximowicz,[1] "Ueber den Ursprung des Parfums
Ylang-Ylang," contains only a confirmation of the derivation of the
perfume from Cananga.
[Footnote 1: Just's "Botanischer Jahresbericht," 1875, 973.]
_Cananga odorata_ is a tree attaining to a height of 60 feet, with few
but abundantly ramified branches. The shortly petioled long acuminate
leaves, arranged in two rows, attain a length of 18 centimeters and a
breadth of 7 centimeters; the leaf is rather coriaceous, and slightly
downy only along the nerves on the under side. The handsome and imposing
looking flowers of the _Cananga odorata_ occur to the number of four on
short peduncles. The lobes of the tripartite leathery calyx are finally
bent back. The six lanceolate petals spread out very nearly flat, and
grow to a length of 7 centimeters and a breadth of about 12 millimeters;
they are longitudinally veined, of a greenish color, and dark brown when
dried. The somewhat bell-shaped elegantly drooping flowers impart quite
a handsome appearance, although the floral beauty of other closely
allied plants is far more striking. The filaments of the Cananga are
very numerous; the somewhat elevated receptacle has a shallow depression
at the summit. The green berry-like fruit is formed of from fifteen to
twenty tolerably long stalked separate carpels which inclose three to
eight seeds arranged in two rows. The umbel-like peduncles are situated
in the axils of the leaves or spring from the nodes of leafless
branches. The flesh of the fruit is sweetish and aromatic. The flowers
possess a most exquisite perfume, frequently compared with hyacinth,
narcissus, and cloves.
_Cananga odorata_, according to Hooker and Thomson or Bentham and
Hooker,[1] is the only species of this genus; the plants formerly
classed together with it under the names _Unona_ or _Uvaria_, among
which some equally possess odorous flowers, are now distributed between
those two genera, which are tolerably rich in species. From _Uvaria_
the _Cananga_ differs in its valvate petals, and from _Unona_ in the
arrangement of the seeds in two rows.
[Footnote 1: "Genera Plantarum," i, (1864), 24.]
_Cananga odorata_ is distributed throughout all Southern Asia, mostly,
however, as a cultivated plant. In the primitive forest the tree is much
higher, but the flowers are, according to Blume, almost odorless. In
habit the Cananga resembles the _Michelia champaca_, L.,[1] of the
family Magnoliaceae, an Indian tree extraordinarily prized on account of
the very pleasant perfume of its yellow flowers, and which was already
highly celebrated in ancient times in India. Among the admired fragrant
flowers which are the most prized by the in this respect pampered
Javanese, the "Tjempaka" (_Michelia champaca_) and the "Kenangga wangi"
(_Cananga odorata_)[2] stand in the first rank.
[Footnote 1: A beautiful figure of this also is given in Blume's "Flora
Javae," iii., Magnoliaceae, tab. I.]
[Footnote 2: Junghuhn, Java, Leipsic, 1852, 166.]
It is not known to me whether the oil of cananga was prepared in former
times. It appears to have first reached Europe about 1864; in Paris and
London its choice perfume found full recognition.[1] The quantities,
evidently only very small, that were first imported from the Indian
Archipelago were followed immediately by somewhat larger consignments
from Manila, where German pharmacists occupied themselves with the
distillation of the oil.[2]
[Footnote 1: _Jahresbericht d. Pharmacie_, by Wiggers and Husemann,
1867, 422.]
[Footnote 2: _Jahresbericht_, 1868, 166.]
Oscar Reymann and Adolf Ronsch, of Manila, exhibited the ilang-ilang oil
in Paris in 1878; the former also showed the Cananga flowers. The oil
of the flowers of the before-mentioned _Michelia champaca_, which stood
next to it, competes with the cananga oil, or ilang-ilang oil, in
respect to fragrance.[1] How far the latter has found acceptance is
difficult to determine; a lowering of the price which it has undergone
indicates probably a somewhat larger demand. At present it may be
obtained in Germany for about 600 marks (L30) the kilogramme.[2] Since
the Cananga tree can be so very easily cultivated in all warm countries,
and probably everywhere bears flowers endowed with the same pleasant
perfume, it must be possible for the oil to be produced far more
cheaply, notwithstanding that the yield is always small.[3] It may be
questioned whether the tree might not, for instance, succeed in Algeria,
where already so many exotic perfumery plants are found.
[Footnote 1: _Archiv der Pharmacie_, ccxiv. (1879), 18.]
[Footnote 2: According to information kindly supplied by Herr Reymann,
in Paris, Nice, and Grasse, annually about 200 kilogrammes are used; in
London about 50 kilogrammes, and equally as much in Germany (Leipsic,
Berlin, Frankfort).]
[Footnote 3: 25 grammes of oil from 5 kilogrammes of flowers, according
to Reymann.]
According to Guibourt,[1] the "macassar oil," much prized in Europe for
at least some decades as a hair oil, is a cocoa nut oil digested with
the flowers of _Cananga odorata_ and _Michelia champaca_, and colored
yellow by means of turmeric. In India unguents of this kind have always
been in use.
[Footnote 1: _Histoire Naturelle des Drogues Simples_, iii. (1850),
675.]
The name "Cananga" is met with in Germany as occurring in former times.
An "Oleum destillatum Canangae" is mentioned by the Leipsic apothecary,
Joh. Heinr. Linck[1] among "some new exotics" in the "Sammlung von
Naturund Medicin- wie, auch hierzu gehorigen Kunst- und Literatur
Geschichten, so sich Anno 1719 in Schlesien und andern Laendern begeben"
(Leipsic und Budissin, 1719). As, however, the fruit of the same tree
sent together with this cananga oil is described by Linck as uncommonly
bitter, he cannot probably here refer to the present _Cananga odorata_,
the fruit-pulp of which is expressly described by Humph and by Blume as
sweetish. Further an "Oleum Canangae, Camel-straw oil," occurs in 1765 in
the tax of Bremen and Verden.[2] It may remain undetermined whether this
oil actually came from "camel-straw," the beautiful grass _Andropogon
laniger_.
[Footnote 1: Compare Flueckiger, "Pharmakognosic," 2d edit, 1881, p.
152.]
[Footnote 2: Flueckiger, "Documente zur Geschichte der Pharmacie," Halle
(1876), p 93.]
From a chemical point of view cananga oil has become interesting because
of the information given by Gal,[1] that it contains benzoic acid, no
doubt in the form of a compound ether. So far as I, at the moment,
remember the literature of the essential oils, this occurrence of
benzoic acid in plants stands alone,[2] although in itself it is not
surprising, and probably the same compound will yet be frequently
detected in the vegetable kingdom. As it was convenient to test the
above statement by an examination I induced Herr Adolf Convert,
a pharmaceutical student from Frankfort-On-Main, to undertake an
investigation of ilang-ilang oil in that direction. The oil did not
change litmus paper moistened with alcohol. A small portion distilled
at 170 deg. C.; but the thermometer rose gradually to 290 deg., and at a still
higher temperature decomposition commenced. That the portions passing
over below 290 deg. had a strong acid reaction already indicated the
presence of ethers. Herr Convert boiled 10 grammes of the oil with 20
grammes of alcohol and 1 gramme of potash during one day in a retort
provided with a return condenser. Finally the alcohol was separated by
distillation, the residue supersaturated with dilute sulphuric acid, and
together with much water submitted to distillation until the distillate
had scarcely an acid reaction. The liquid that had passed over was
neutralized with barium carbonate, and the filtrate concentrated, when
it yielded crystals, which were recognized as nearly pure acetate. The
acid residue, which contained the potassium sulphate, was shaken with
ether; after the evaporation of the ether there remained a crystalline
mass having an acid reaction which was colored violet with ferric
chloride. This reaction, which probably may be ascribed to the account
of a phenol, was absent after the recrystallization of the crystalline
mass from boiling water. The aqueous solution of the purified
crystalline scales then gave with ferric chloride only a small
flesh-colored precipitate. The crystals melted at 120 deg. C. In order
to demonstrate the presence of benzoic acid Herr Convert boiled the
crystals with water and silver oxide and dried the scales that separated
from the cooling filtrate over sulphuric acid. 0.0312 gramme gave upon
combustion 0.0147 gramme of silver, or 47.1 per cent. The benzoate of
silver contains 46.6 per cent, of metal; the crystals prepared from the
acid of ilang-ilang oil were, therefore, benzoate of silver. For the
separation of the alcoholic constituent, which is present in the form of
an apparently not very considerable quantity of benzoic ether, far more
ilang-ilang oil would be required than was at command.
[Footnote 1: _Comptes Rendus_, lxxvi. (1873), 1428, and abstracted in
the _Pharmaceutical Journal_ [3], iv., p. 28; also in _Jahresbericht_,
1873, p. 431.]
[Footnote 2: Overlooking Peru balsam and Tolu balsam.]
Besides the benzoic ether and, probably, a phenol, mentioned above,
there may be recognized in ilang-ilang oil an aldehyde or ketone,
inasmuch as upon shaking it with bisulphite of sodium I observed the
formation of a very small quantity of crystals. That Gal did not obtain
the like result must at present remain unexplained. Like the benzoic
acid the acetic acid is, no doubt, present in cananga oil in the form of
ether.
* * * * *
CHIAN TURPENTINE.
The following letter has been received by the editors of the _Repertoire
de Pharmacie:_ For some months past, a good deal has been heard about a
product of our island that had quite fallen into disuse, and which
no one cared to gather, so much had the demand fallen off because a
substitute for it had been found in Europe; I mean Chian turpentine.
As this product is destined to take a certain part in the treatment of
cancer, according to some English physicians, permit me, sir, to give
your readers a few interesting details, obtained on the spot, concerning
the turpentine tree and its product.
The turpentine tree (_Pistacia terebinthus_ L.) has existed in our
island for many centuries, judging from the enormous dimensions of some
of these trees, compared, too, with their slow rate of growth. The
trunks of some measure from 4 to 5 meters in circumference, and their
heights vary from 15 to 20 meters. On my own land there is an enormous
tree, by far the largest on the island, the circumference of its
trunk being 6 meters. Many of these great trees have been used in the
construction of mills, presses, etc., on account of the hardness of
their wood. It is in the vicinity of the town and in three or four
neighboring villages that these trees are found. To-day, at a careful
estimate, there may be 1,500 trees capable of yielding 2,000 kilos of
turpentine, mixed with at least 30 per cent of foreign matter. There are
no appliances for refining the product here, except the sieves through
which it is passed to remove the pebbles and bits of wood which are
found in it.
It is gathered from incisions made in the tree in June. Axes are used
for this purpose, and the incision must be through the whole thickness
of the bark. Through these outlets the turpentine falls to the foot of
the tree, and mixes with the earth there. On its first appearance
the turpentine is of a sirupy consistence, and is quite transparent;
gradually it becomes more opaque, and of a yellowish-white color. It
is at this period also that it gives off its characteristic odor most
abundantly.
It is, however, not the product "turpentine" that is most esteemed by
the natives, but the fruit of the tree, a kind of drupe disposed in
clusters. The fruit is improved by the incisions made in the tree for
the escape of the turpentine, otherwise the resin, having no other
outlet, would impregnate the former, hinder its complete development,
and render it useless for the purposes for which it is cultivated. One
circumstance worth noting is that, as soon as the fruit commences to
ripen, the flow of turpentine completely ceases. This is toward August;
the fruit is then green; it is gathered, dried in the sun, bruised, and
a fine yellowish-green oil is drawn from it, which is soluble in ether.
This oil is used for alimentary purposes, but rarely for illumination
since the introduction of petroleum. It is mostly used in making sweet
cakes, and often as a substitute for butter, in all cases where the
latter is employed. I use it daily myself without perceiving any
difference.
I may here be permitted to correct a slight mistake that has crept
into several standard botanical works. It is therein stated that the
inhabitants of this country extract from the fruit of the lentisc
(_Pistacia lentiscus_ L., a well-known shrub growing on this island,
from which Chian mastic is obtained), an alimentary and illuminating
oil. This fruit has never been gathered for its oil within the memory
of man. The lentisc has probably been thus mistaken for the turpentine
tree.
For the last twenty years the gathering of turpentine has been almost
abandoned, although the incisions in the trees have been regularly made,
but the value was so small that proprietors did not care to collect it,
and left it to run to waste. There were but a few pharmacists of Smyrna
and the neighboring islands who took a small quantity for making
medicinal plasters. An utterly insignificant quantity found its way
into Europe. How is it then that, after so many years, it was found in
Europe? The problem is easily explained--the greater part came from
Venice. This is indubitable, and, lately, an English chemist, Mr. W.
Martindale, in a communication to the Chemical Society of London,
expressed doubts as to the authenticity of the turpentine used in the
treatment of cancer. If turpentine can really somewhat relieve this
disease, and if this treatment is generally accepted in Europe, I much
fear you will only obtain substitutions of very inferior quality to the
turpentine produced in our island.
This year the Chians have been surprised by an extensive demand for this
product, from London in the first place, and secondly from Vienna, and
the proprietors, although but poorly provided at the moment, sent away
nearly 600 kilos Paris has not yet made any demand. Yours, etc.,
DR. STIEPOWICH.
Chio, Turkey.
* * * * *
ON THE CHANGE OF VOLUME WHICH ACCOMPANIES THE GALVANIC DEPOSITION OF A
METAL.
By M. E. BOUTY.
In previous notes I have established, first, that the galvanic
depositions experience a change of volume, from which there results a
pressure exercised on the mould which receives them; second, that the
Peltier phenomenon is produced at the surface of contact of an electrode
and of an electrolyte. Fresh observations have caused me to believe that
the two phenomena are connected, and that the first is a consequence
of the second. The Peltier effect can clearly be proved when the
electrolysis is not interfered with by energetic secondary actions, and
particularly with the sulphate and nitrate of copper, the sulphate and
chloride of zinc, and the sulphate and chloride of cadmium. For any one
of these salts it is possible to determine a value, I, of the intensity
of the current which produces the metallic deposit such that, for all
the higher intensities the electrode becomes heated, and such that it
becomes cold for less intensities. I will designate this intensity, I,
under the name of _neutral point of temperatures_.
The new fact which I have observed is, that in the electrolysis of the
same salts it is always possible to lower the intensity of the current
below a limit, I', such that the compression produced by the deposit
changes its direction, that is to say, instead of contracting the
metal dilates in solidifying. This change, although unquestionable,
is sufficiently difficult to produce with sulphate of copper. It is
necessary to employ as a negative electrode a thermometer sensitive
to 1/200 of a degree, and to take most careful precautions to avoid
accidental deformations of the deposit; but the phenomenon can be
observed very easily with nitrate of copper, the sulphate of zinc,
and the chloride of cadmium. There is, therefore, a _neutral point
of compression_ in the same cases where there is a neutral point of
temperatures. With the salts of iron, nickel, etc., for which the
neutral point of temperatures cannot be arrived at, there is also no
neutral point of compression; and the negative electrode always becomes
heated, and the deposit obtained is always a compressing deposit.
I have determined, by the help of observations made with ten different
current strengths, the constants of the formulae which I have explained
elsewhere, and which gives the apparent excess, y, of the thermometer
electrode compressed by the metallic deposit in terms of the time, t,
during which the metal was depositing:
A t
(1) y = -------
B + t
The constant, A, is proportional to the variation of volume of the unit
of volume of the metal. The values of A, without being exactly regular,
are sufficiently well represented within practical limits by the
formula:
(2) A = - a'i + b'i squared,
of the same form as the expression E:
E = - ai + bi squared,
of the heating of the thermometer electrode. Further, every cause which
affects the coefficients, a or b, also affects in the same way a' and
b': such causes being the greater or less dilution of the solution, the
nature of the salt, etc. It is, therefore, impossible not to be struck
by the direct relation of the thermic and mechanical phenomena of which
the negative electrode is the origin. The following is the explanation
which I offer: The thermometer indicates the mean temperature of the
liquid just outside it; this temperature is not necessarily that of the
metal which incloses it. The current, propagated almost exclusively by
the molecules of the decomposed salt, does not act directly to cause a
variation in the temperature of the dissolving molecules; these change
heat with the molecules of the electrolyte, which should be in general
hotter than those when a heating is noticed and colder when a cooling is
observed. Suppose it is found, in the first case, that the metal, at
the moment when it is deposited, is hotter than the liquid, and,
consequently, than the thermometer; it becomes colder immediately after
the deposit, and consequently contracts; the deposit is compressed.
The reverse is the case when the metal is colder than the liquid; the
deposit then dilates. If this hypothesis is correct, the excess, T,
of the temperature of the metal over the liquid which surrounds the
thermometer should be proportional to the contraction, A, represented
by the formula (2), and the neutral point, I', of the contraction
corresponds to the case where the temperature of the metal is precisely
equal to that of the liquid.
It might be expected, perhaps, from the foregoing, that I' = I; this
would take place if the excess of temperature of the metal, measured
by the contraction, were rigorously proportional to the heating of the
liquid, for then the two quantities would be null at the same time.
Careful experiment proves that this is not the case. The sulphate of
copper gives compressing deposits on a thermometer which is undoubtedly
cooling; chloride of zinc of a density 200 can give expanding
deposits on a thermometer which is heating. There is, therefore, no
proportionality; but it must be remarked that the temperature of the
metal which is deposited does not depend only on the quantities of heat
disengaged in an interval of molecular thickness which is infinitely
small compared with the thickness of the layer, of which the variations
of temperature are registered by the thermometer. There is nothing
surprising, therefore, that the two variations of temperature,
according exactly with one another, do not follow identically the same
laws.--_Comptes Rendus._
* * * * *
ANALYSES OF RICE SOILS FROM BURMAH.
By R. ROMANIS, D.Sc., Chemical Examiner, British Burmah.
The analyses of rice soils was undertaken at the instance of the Revenue
Settlement Survey, who wanted to know if the chemical composition of
the soil corresponded in any way to the valuation as fixed from other
evidence. It was found that the amount of phosphoric acid in the soil in
any one district corresponded pretty well with the Settlement Officers'
valuation, but on comparing two districts it was found that the district
which was poorer in phosphoric acid gave crops equal to the richer
one. On inquiry it was found that in the former the rice is grown in
nurseries and then planted out by hand, whereas in the latter, where the
holdings are much larger, the grain is sown broadcast. The practice of
planting out the young crops enables the cultivator to get a harvest 20
per cent. better than he would otherwise do, and hence the poorer land
equals the richer.
The deductions drawn from this investigation are, first, that, climate
and situation being equal, the value of soil depends on the phosphoric
acid in it; and, second, that the planting-out system is far superior to
the broadcast system of cultivation for rice.
Results of two analyses of soils from Syriam, near Rangoon, are
appended:
_Soluble in Hydrochloric Acid_.
I. II.
Virgin Soil.
Organic matter 4.590 8.5?8
Oxide of iron and alumina 8.939 7.179
Magnesia 0.469 0.677
Lime trace. 0.131
Potash 0.138 0.187
Soda 0.136 0.337
Phosphoric acid 0.100 0.108
Sulphuric acid 0.025 0.117
Silica ---- 0.005
-------- ---------
14.397 17.249
_Soluble in Sulphuric Acid_.
Alumina 17.460 15.684
Magnesia 0.459 0.446
Lime 0.286 trace.
Potash 0.616 1.250
Soda 0.317 0.285
--------- ---------
19.138 17.665
_Residue_.
Silica, soluble 11.675 \
69.546
" insoluble 49.477 /
Alumina 3.062 4.178
Lime 0.700 0.134
Magnesia 0.212 trace.
Potash 0.276 1.180
Soda 0.503 1.048
-------- ---------
100.000 100.000
These are alluvial soils from the Delta of the Irrawaddy.
* * * * *
DRY AIR REFRIGERATING MACHINE.
A large number of scientific and other gentlemen interested in
mechanical refrigeration lately visited the works of Messrs. J. & E.
Hall, of Dartford, to inspect the working of one of their improved
horizontal dry air refrigerators!
The machine, which is illustrated below, is designed to deliver about
10,000 cubic feet of cold air per hour, when running at the rate of 100
revolutions per minute, and is capable of reducing the temperature of
the air from 90 deg. above, to about 50 deg. below zero, Fah., with an
initial temperature of cooling water of 90 deg. to 95 deg. Fah. It can,
however, be run at as high a speed as 140 revolutions per minute.
The air is compressed in a water-jacketed, double-acting compression
cylinder, to about 55 lb. per square inch --more or less according to
the temperature of the cooling water--the inlet valve being worked from
a cam on the crank shaft, to insure a full cylinder of air at each
stroke, and the outlet valves being self acting, specially constructed
to avoid noise in working and breakages, which have given rise to so
much annoyance in other cold air machines. The compressed air, still at
a high temperature, is then passed through a series of tubular coolers,
where it parts with a great deal of its heat, and is reduced to within
4 deg. or 5 deg. of the initial temperature of the cooling water. Here
also a considerable portion of the moisture, which, when fresh air
is being used, must of necessity enter the compression cylinder, is
condensed and deposited as water.
[Illustration: COMPRESSION CYLINDER. SCALE 1/60]
After being cooled, the compressed air is then admitted to the expansion
cylinder, but as it still contains a large quantity of water in
solution, which, if expansion was carried immediately to atmospheric
pressure, would, from the extreme cold, be converted into snow and ice,
with a positive certainty of causing great trouble in the valves and
passages. It is got rid of by a process invented by Mr. Lightfoot,
which is at the same time extremely simple and beautiful in action, and
efficient. Instead of reducing the compressed air at once to atmospheric
pressure, it is at first only partially expanded to such an extent that
the temperature is lowered to about 35 deg. to 40 deg. Fah., with the
result that very nearly the whole of the contained aqueous vapor is
condensed into water. The partially expanded air which now contains the
water as a thick mist is then admitted into a vessel containing a number
of grids, through which it passes, parting all the while with its
moisture, which gradually collects at the bottom and is blown off. The
surface area of the grids is so arranged that by the time the air has
passed through them it is quite free from moisture, with the exception
of the very trifling amount which it can hold in solution at about 35
deg. Fah., and 30 lb. pressure. The expansion is then continued to
atmospheric pressure and the cooled air containing only a trace of snow
is then discharged ready for use into a meat chamber or elsewhere. In
small machines the double expansion is carried out in one cylinder
containing a piston with a trunk, the annulus forming the first
expansion and the whole piston area the second, but in larger machines
two cylinders of different sizes are used, just as in an ordinary
compound engine. To compensate for the varying temperature of the
cooling water the cut-off valve to the first or primary expansion is
made adjustable; and this can either be regulated as occasion requires
by hand, or else automatically. The temperature in the depositors being
kept constant under all variations in cooling water, there is the same
abstraction of moisture in the tropics as in colder climates, and the
cold air finally discharged from the machine is also kept at a uniform
temperature.
[Illustration: Expansion Cylinder. Scale 1/60.92 deg. F. temperature of
entering air. Cooling water entering in at 86 deg. F.]
[Illustration: Expansion Cylinder. Scale 1/60. 68 deg. F. temperature of
entering air. Cooling water entering in at 65 deg. F. 125 revs. per minute,
or 312 ft. per minute per piston speed.]
The diagrams are reduced from the originals, taken from the compression
cylinder when running at the speed of 125 revolutions per minute, and
also from the expansion cylinder, the first when the cooling water
was entering the coolers at 86 deg. Fah., and the latter when this
temperature was reduced to 65 deg. Fah. In all cases the compressed
air is cooled down to within from 3 deg. to 5 deg. of the initial
temperature of the cooling water, thus showing the great efficiency
of the cooling apparatus. The machine has been run experimentally at
Dartford, under conditions perhaps more trying than can possibly occur,
even in the tropics, the air entering the compression cylinder being
artificially heated up to 85 deg. and being supersaturated at that
temperature by a jet of steam laid on for the purpose. In this case no
more snow was formed than when dealing with aircontaining a very much
less proportion of moisture. The vapor was condensed previous to final
expansion and abstracted as water in the drying apparatus. The machine
was exhibited at work in connection with a cold chamber which was
kept at a temperature of about 10 deg. Fah., besides which several
hundredweight of ice were made in the few days during which the
experiments lasted. This machine is in all respects an improvement on
the machine which we have already illustrated. In that machine Messrs.
Hall were trammeled by being compelled to work to the plans of others.
In the present case the machine has been designed by Mr. Lightfoot, and
appears to leave little to be desired. It is a new thing that a cold air
machine may be run at any speed from 32 to 120 revolutions per minute.
In its action it is perfectly steady, and the cold air chamber is kept
entirely clear of snow. The dimensions of the machine are also eminently
favorable to its use on board ship.-_The Engineer_.
[Illustration: DRY AIR REFRIGERATING MACHINE]
* * * * *
THOMAS'S IMPROVED STEAM WHEEL.
The rotary or steam wheel, the invention of J.E. Thomas, of Carlinville,
Ill., shown in the annexed figure, consists of a wheel with an iron rim
inclosed within a casing or jacket from which nothing protrudes except
the axle which carries the driving pulley, and the grooved distributing
disk. Within this jacket, which need not necessarily be steam-tight,
there is a movable piece, K, which, pressing against the rim, renders
steam-tight the channel in which the pistons move when driven by the
steam. At the extremities of this channel there are plates which
are kept pressed against the wheel by means of spiral springs, thus
rendering the channel perfectly tight.
The steam enters the closed space (which forms one-fourth of the
circumference) through the slide-valve, S, presses against the pistons,
d, and causes the wheel to revolve in the direction of the arrows.
The slide-valve is closed by the action of the external distributing
mechanism, the piston passes beyond the steam-outlet, A, and a new
piston then comes in play. Altogether, there are six of these pistons,
each one working in an aperture in the rim, and kept pressed outwardly
by means of a spiral spring. The steam acts constantly on the same lever
arm and meets with no counter-pressure. The other defects, likewise, of
the ordinary steam engines in use are obviated to such an extent that
the effective power of the steam-wheel is 50 per cent, greater than that
of other and more complicated machines--at least this is the experience
of the inventor.
[Illustration: IMPROVED STEAM-WHEEL.]
To the inner ends of the pistons there are attached rods which
pass through the rim of the wheel (where they are provided with
stuffing-boxes) and abut against spiral springs. These rods are, in
addition, connected with levers, h, which are pivoted on the spokes of
the wheel, and whose other extremities carry rods, 2. These latter run
through guides on the external face of the rim of the wheel and engage
by means of friction-rollers, in an undulating groove formed in the
inner surface of the jacket. When a piston arrives in front of the upper
extremity of the steam channel, the friction roller at that moment
enters one of the depressions in the groove, and thus lifts up the
piston and allows it to pass freely beyond the plate which closes the
channel.
* * * * *
THE AMERICAN SOCIETY OF CIVIL ENGINEERS.
ADDRESS OF THE PRESIDENT, JAMES BICHENO FRANCIS, AT THE THIRTEENTH
ANNUAL CONVENTION OF THE SOCIETY AT MONTREAL, JUNE 15, 1881.
You have assembled in convention for the first time outside the limits
of the United States, and I congratulate you on the selection of this
beautiful city, in which and its immediate neighborhood there are so
many interesting engineering works, constructed with the skill and
solidity characteristic of the British school of engineering. Nine of
our members are Canadian engineers, which must be the excuse of the
other members for invading foreign territory.
The society was organized November 3, 1852, and actively maintained up
to March 2, 1855. Eleven only of the present members date from this
period. October 2, 1867, the society was reorganized on a wider basis,
and from that time to the present it has been constantly increasing in
interest and usefulness.
The membership of the society is now as follows:
Honorary members........ 11
Corresponding members... 3
Members................. 491
Associates.............. 21
Juniors................. 57
Fellows................. 53
----
Total................... 636
During the last year we have lost six members by death and five by
resignation, and fifty-six new members have been elected and qualified.
The most interesting event to the society since the last convention has
been the purchase of a house in the City of New York, as a permanent
home, at a cost of $30,000. This has been accomplished, so far, without
taxing the resources of the society, the required payments having been
met by subscription. The sum of $11,900 had been subscribed to the
building fund up to the 25th ult., by seventy members and twenty-nine
friends of the society who are not members. The subscription is still
open, and it is expected that large additions will be made to it by
members and their friends to enable the society to make the remaining
payments without embarrassment.
Meetings of the society are held twice in each month during ten months
in the year, for the reading and discussion of papers and other
purposes. The new house affords much better accommodations for these
purposes than we have ever had before, and also for the library, which
now contains 8,850 books and pamphlets, and is constantly increasing. A
catalogue of the library is being prepared. Part I., embracing railroads
and the transactions of scientific societies, has been printed and
furnished to members.
WATER POWER.
Water power in many of the States is abundant and contributes largely to
their prosperity. Its proper development calls for the services of the
civil engineer, and as it is the branch of the profession with which I
am most familiar, I propose to offer a few remarks on the subject.
The earliest applications were to grist and saw mills; carding and
fulling mills soon followed; these were essential to the comfort of the
early settlers who relied on home industries for shelter, food, and
clothing, but with the progress of the country came other requirements.
The earliest application of water power to general manufacturing
purposes appears to have been at Paterson, New Jersey, where "The
Society for Establishing Useful Manufactures" was formed in the year
1791. The Passaic River at this point furnishes, when at a minimum,
about eleven hundred horse power continuously night and day.
The water power at Lowell, Massachusetts, was begun to be improved for
general manufacturing purposes in 1822. The Merrimack River at this
point has a fall of thirty-five feet, and furnishes, at a minimum, about
ten thousand horse power during the usual working hours.
At Cohoes, in the State of New York, the Mohawk River has a fall
of about one hundred and five feet, which was brought into use
systematically very soon after that at Lowell, and could furnish about
fourteen thousand horse power during the usual working hours, but
the works are so arranged that part of the power is not available at
present.
At Manchester, New Hampshire, the present works were commenced in 1835.
The Merrimack River at this point has a fall of about fifty-two feet,
and furnishes, at a minimum, about ten thousand horse power during the
usual working hours.
At Lawrence, Massachusetts, the Essex Co. built a dam across the
Merrimack River, commencing in 1845, and making a fall of about
twenty-eight feet, and a minimum power, during the usual working hours,
of about ten thousand horse power.
At Holyoke, Massachusetts, the Hadley Falls Co. commenced their works
about 1845, for developing the power of the Connecticut River at that
point, where there is a fall of about fifty feet, and at a minimum,
about seventeen thousand horse power during the usual working hours.
At Lewiston, Maine, the fall in the Androscoggin River is about fifty
feet; its systematic development was commenced about 1845, and with the
improvement of the large natural reservoirs at the head waters of the
river, now in progress, it is expected that a minimum power, during
the usual working hours, of about eleven thousand horse power will be
obtained.
At Birmingham, Connecticut, the Housatonic Water Co. have developed the
water power of the Housatonic River by a dam, giving twenty-two feet
fall, furnishing at a minimum about one thousand horse power during the
usual working hours.
The Dundee Water and Land Co., about 1858, developed the power of the
Passaic River, at Passaic, New Jersey, where there is a fall of about
twenty-two feet, giving a minimum power, during the usual working hours,
of about nine hundred horse power.
The Turners Falls Co., in 1866, commenced the development of the power
of the Connecticut River at Turners Falls, Massachusetts, by building a
dam on the middle fall, which is about thirty-five feet, and furnishes
a minimum power, during the usual working hours, of about ten thousand
horse power.
I have named the above water powers as being developed in a systematic
manner from their inception, and of which I have been able to obtain
some data. In the usual process of developing a large water power, a
company is formed, who acquire the title to the property, embracing the
land necessary for the site of the town, to accommodate the population
which is sure to gather around an improved water power. The dam and
canals or races are constructed, and mill sites, with accompanying
rights to the use of the water, are granted, usually by perpetual leases
subject to annual rents. This method of developing water power is
distinctly an American idea, and the only instance where it has been
attempted abroad, that I know of, is at Bellegarde in France, where
there is a fall in the Rhone of about thirty-three feet. Within the last
few years works have been constructed for its development, furnishing a
large amount of power, but from the great outlay incurred in acquiring
the titles to the property, and other difficulties, it has not been a
financial success.
The water powers I have named are but a small fraction of the whole
amount existing in the United States and the adjoining Dominion of
Canada. There is Niagara, with its two or three millions of horse power;
the St. Lawrence, with its succession of falls from Lake Ontario to
Montreal; the Falls of St. Antony, at Minneapolis; and many other falls,
with large volumes of water, on the upper Mississippi and its branches.
It would be a long story to name even the large water powers, and the
smaller ones are almost innumerable. In the State of Maine a survey of
the water power has recently been made, the result, as stated in the
official report, being "between one and two millions of horse power,"
part of which will probably not be available. There is an elevated
region in the northern part of the South Atlantic States, exceeding in
area one hundred thousand square miles, in which there is a vast amount
of water power, and being near the cotton fields, with a fine climate,
free from malaria, its only needs are railways, capital, and population,
to become a great manufacturing section.
The design and construction of the works for developing a large water
power, together with the necessary arrangements for utilizing it and
providing for its subdivision among the parties entitled to it according
to their respective rights, affords an extensive field for civil
engineers; and in view of the vast amount of it yet undeveloped, but
which, with the increase of population and the constantly increasing
demand for mechanical power as a substitute for hand labor, must come
into use, the field must continue to enlarge for a long time to come.
There are many cases in which the power of a waterfall can be made
available by means of compressed air more conveniently than by the
ordinary motors. The fall may be too small to be utilized by the
ordinary motors; the site where the power is wanted may be too distant
from the waterfall; or it may be desired to distribute the power in
small amounts at distant points.[1] A method of compressing air by means
of a fall of water has been devised by Mr. Joseph P. Frizell, C.E.,
of St. Paul, Minnesota, which, from the extreme simplicity of the
apparatus, promises to find useful applications. The principle on which
it operates is, by carrying the air in small bubbles in a current
of water down a vertical shaft, to the depth giving the desired
compression, then through a horizontal passage in which the bubbles rise
into a reservoir near the top of this passage, the water passing on and
rising in another vertical or inclined passage, at the top of which it
is discharged, of course, at a lower level than it entered the first
shaft.
[Footnote 1: _Journal of the Franklin Institute_ for September, 1877.]
The formation at waterfalls is usually rock, which would enable the
passages and the reservoir for collecting the compressed air to be
formed by simple excavations, with no other apparatus than that required
to charge the descending column of water with the bubbles of air,
which can be done by throwing the water into violent commotion at its
entrance, and a pipe and valve for the delivery of the air from the
reservoir.
The transfer of power by electricity is one of the problems now engaging
the attention of electricians, and it is now done in Europe in a
small way. Sir William Thomson stated in evidence before an English
parliamentary committee, two years ago, that he looked "forward to the
Falls of Niagara being extensively used for the production of light and
mechanical power over a large area of North America," and that a copper
wire half an inch in diameter would transmit twenty-one thousand horse
power from Niagara to Montreal, Boston, New York, or Philadelphia. His
statements appear to have been based on theoretical considerations; but
there is no longer any doubt as to the possibility of transferring power
in this manner--its practicability for industrial purposes must
be determined by trial. Dr. Paget Higgs, a distinguished English
electrician, is now experimenting on it in the City of New York.
Great improvements in reaction water wheels have been made in the United
States within the last forty years. In the year 1844, the late Uriah
Atherton Boyden, a civil engineer of Massachusetts, commenced the design
and construction of Fourneyron turbines, in which he introduced various
improvements and a general perfection of form and workmanship, which
enabled a larger percentage of the theoretical power of the water to be
utilized than had been previously attained. The great results obtained
by Boyden with water wheels made in his perfect manner, and, in some
instances, almost regardless of cost, undoubtedly stimulated others to
attempt to approximate to these results at less cost; and there are now
many forms of wheel of low cost giving fully double the power, with the
same consumption of water, that was obtained from most of the older
forms of wheels of the same class.
ANCHOR ICE.
A frequent inconvenience in the use of water power in cold climates is
that peculiar form of ice called anchor or ground ice. It adheres to
stones, gravel, wood, and other substances forming the beds of streams,
the channels of conduits, and orifices through which water is drawn,
sometimes raising the level of water courses many feet by its
accumulation on the bed, and entirely closing small orifices through
which water is drawn for industrial purposes. I have been for many years
in a position to observe its effects and the conditions under which it
is formed.
The essential conditions are, that the temperature of the water is at
its freezing point, and that of the air below that point; the surface of
the water must be exposed to the air, and there must be a current in the
water.
The ice is formed in small needles on the surface, which would remain
there and form a sheet if the surface was not too much agitated, except
for a current or movement in the body of water sufficient to maintain
it in a constant state of intermixture. Even when flowing in a regular
channel there is a continued interchange of position of the different
parts of a stream; the retardation of the bed causes variations in the
velocity, which produce whirls and eddies and a general instability in
the movement of the water in different parts of the section--the result
being that the water at the bottom soon finds its way to the surface,
and the reverse. I found by experiments on straight canals in earth and
masonry that colored water discharged at the bottom reached the surface
at distances varying from ten to thirty times the depth.[1] In natural
water courses, in which the beds are always more or less irregular, the
disturbance would be much greater. The result is that the water at the
surface of a running stream does not remain there, and when it leaves
the surface it carries with it the needles of ice, the specific gravity
of which differs but little from that of the water, which, combined with
their small size, allows them to be carried by the currents of water in
any direction. The converse effect takes place in muddy streams. The mud
is apparently held in suspension, but is only prevented from subsiding
by the constant intermixture of the different parts of the stream; when
the current ceases the mud sinks to the bottom, the earthy particles
composing it, being heavier than water, would sink in still water in
times inversely proportional to their size and specific gravity. This,
I think, is a satisfactory explanation of the manner in which the ice
formed at the surface finds its way to the bottom; its adherence to the
bottom, I think, is explained by the phenomenon of _regelation_, first
observed by Faraday; he found that when the wetted surfaces of two
pieces of ice were pressed together they froze together, and that this
took place under water even when above the freezing point. Professor
James D. Forbes found that the same thing occurred by mere contact
without pressure, and that ice would become attached to other substances
in a similar manner. Regelation was observed by these philosophers in
carefully arranged experiments with prepared surfaces fitting together
accurately, and kept in contact sufficiently long to allow the freezing
together to take place. In nature these favorable conditions would
seldom occur in the masses of ice commonly observed, but we must admit,
on the evidence of the recorded experiments, that, under particular
circumstances, pieces of ice will freeze together or adhere to other
substances in situations where there can be no abstraction of heat.
[Footnote 1: Paper clx., in the Transactions of the Society, 1878, vol.
vii., pages 109-168.]
When a piece of ice of considerable size comes in contact under water
with ice or other substance, it would usually touch in an area very
small in proportion to its mass, and other forces acting upon it,
and tending to move it, would usually exceed the freezing force, and
regelation would not take place. In the minute needles formed at the
surface of the water the tendency to adhere would be much the same as in
larger masses touching at points only, while the external forces acting
upon them would be extremely small in proportion, and regelation would
often occur, and of the immense number of the needles of ice formed at
the surface enough would adhere to produce the effect which we observe
and call anchor ice. The adherence of the ice to the bed of the stream
or other objects is always downstream from the place where they are
formed; in large streams it is frequently many miles below; a large
part of them do not become fixed, but as they come in contact with each
other, regelate and form spongy masses, often of considerable size,
which drift along with the current, and are often troublesome
impediments to the use of water power.
Water powers supplied directly from ponds or rivers, or canals frozen
over for along distance immediately above the places from which the
water is drawn, are not usually troubled with anchor ice, which, as I
have stated, requires open water, upstream, for its formation.
* * * * *
A PAIR OF COTTAGES.
This drawing has been admitted into the Exhibition of the Royal Academy
this year. The cottages are of red brick, tiled roof, white woodwork, as
usual, rough-cast in the gables; but they are not built yet. Design of
Arthur Cawston.--_Building News_.
[Illustration: SUGGESTIONS IN ARCHITECTURE.--A PAIR OF ENGLISH
COTTAGES.--BY A. CAWSTON.]
* * * * *
DELICATE SCIENTIFIC INSTRUMENTS.
By EDGAR L. LARKIN, New Windsor Observatory, New Windsor, Illinois.
Within the past five years, scientific men have surpassed previous
efforts in close measurement and refined analysis. By means of
instruments of exceeding delicacy, processes in nature hitherto unknown,
are made palpable to sense. Heat is found in ice, light in seeming
darkness, and sound in apparent silence. It seems that physicists and
chemists have almost if not quite reached the ultimate atoms of matter.
The mechanism must be sensitive, as such properties of matter as heat,
light, electricity, magnetism, and actinism, are to be handled, caused
to vanish and reappear, analyzed and measured. With such instruments
nature is scrutinized, revealing new properties, strange motions,
vibrations, and undulations. Throughout the visible universe, the
faintest pulsations of atoms are detected, and countless millions of
infinitely small waves, bearing light, heat, and sound, are discovered
and their lengths determined. Refined spectroscopic analysis of light is
now made so that when any material burns, no matter what its distance,
its spectrum tells what substance is burning. When any luminous body
appears, it can be told whether it is approaching or receding, or
whether it shines by its own or reflected light; whence it is seen that
rays falling on earth from a flight of a hundred years, are as sounding
lines dropped in the appalling depths of space. We wish to describe a
few of these intricate instruments, and mention several far-reaching
discoveries made by their use; beginning with mechanism for the
manipulation of light. Optics is based on the accidental discovery that
a piece of glass of certain shape will draw light to a focus, forming an
image of any object at that point. The next step was in learning that
this image can be viewed with a microscope, and magnified; thus came the
telescope revealing unheard of suns and galaxies. The first telescopes
colored everything looked at, but by a hundred years of mathematical
research, the proper curvature of objectives formed of two glasses was
discovered, so that now we have perfect instruments. Great results
followed; one can now peer into the profound solitudes of space,
bringing to view millions of stars, requiring light 5,000 years to
traverse their awful distance, and behold suns wheeling around suns, and
thousands of nebulae, or agglomerations of stars so distant as to send
us confused light, appearing like faint gauze like structures in
measureless voids. The modern telescope has astonishing power, thus:
When Mr. Clark finished the great twenty-six-inch equatorial, now at
Washington, he tested its seeing properties. A photographic calligraph,
whose letters were so fine as to require a microscope to see them, was
placed at a distance of three hundred feet. Mr. Clark turned the great
eye upon the invisible thing and read the writing with ease. But a
greater feat than this was accomplished by the same instrument-- the
discovery of the two little moons of Mars, by Prof. Asaph Hall, in 1877.
They are so small as to be incapable of measurement by ordinary means,
but with an ingenious photometer devised by Prof. Pickering of Harvard
College, he determined the outer satellite to be six and the inner seven
miles in diameter. The discovery of these minute bodies seems past
belief, and will appear more so, when it is told that the task is equal
to that of viewing a luminous ball two inches in diameter suspended
above Boston, by the telescope situated in the city of New York.
(Newcomb and Holden's Astronomy, p. 338.)
Phobos, the nearest moon, is only 4,000 miles from the surface of Mars,
and is obliged to move with such great velocity to prevent falling, that
it actually makes a circuit about its primary in only seven hours and
thirty-eight minutes. But Mars turns on _its_ axis in twenty-four hours
and thirty-seven minutes, so the moon goes round three times, while Mars
does once, hence it rises in the west and sets in the east, making one
day of Mars equal three of its months. This moon changes every two
hours, passing all phases in a single martial night; is anomalous in
the solar system, and tends to subvert that theory of cosmic evolution
wherein a rotating gaseous sun cast off concentric rings, afterward
becoming planets. Astronomers were not satisfied with the telescope;
true, they beheld the phenomena of the solar system; planets rotating on
axes, and satellites revolving about them. They saw sunspots, faculae,
and solar upheaval; watched eclipses, transits, and the alternations of
summer and winter on Mars, and detected the laws of gravity and motion
in the system to which the earth belongs. They then devised the
micrometer. This is a complex mechanism placed in the focus of a
telescope, and by its use any object, providing it shows a disk, no
matter what its distance, can be measured. It consists of spider webs
set within a graduated metallic circle, the webs movable by screws, and
the whole instrument capable of rotating about the collimation axis of
the telescope. The screw head is a circle ruled to degrees and minutes,
and turns in front of a fixed vernier in the field of a reading
microscope. One turn of the screw moves the web a certain number
of seconds; then as there are 360 deg. in a circle,
one-three-hundred-and-sixtieth of a turn moves the web one-three-hundred
and-sixtieth of the amount, and so on. Thus, when two stars are seen in
the field, one web is moved by the screw until the fixed line and the
movable one are parallel, each bisecting a star. By reading with the
microscope the number of degrees turned, the distance apart of the stars
becomes known; the distance being learned, position is then sought; the
observance of which led to one of the greatest discoveries ever made by
man. The permanent line of the micrometer is placed in the line joining
the north and south poles of the heavens, and brought across one of the
stars; the movable web is then rotated until it bisects the other, and
then the angle between the webs is recorded. Double stars are thus
measured, first in distance, and second, their position. After this, if
any movement of the stars takes place, the tell tale micrometer at once
detects it.
In 1780, Sir Wm. Herschel measured double stars and made catalogues with
distances and positions. Within twenty years, he startled intellectual
man with the statement that many of the fixed stars actually move--one
great sun revolving around another, and both rotating about their common
center of gravity. If we look at a double star with a small telescope,
it looks just like any other; using a little larger glass, it changes
appearance and looks elongated; with a still better telescope, they
become distinctly separated and appear as two beautiful stars whose
elements are measured and carefully recorded, in order to see if they
move. Herschel detected the motion of fifty of these systems, and
revolutionized modern astronomy. Astronomers soared away from the little
solar system, and began a minute search throughout the whole sidereal
heavens. Herschel's catalogue contained four hundred double suns, only
fifty of which were known to be in revolution. Since then, enormous
advance has been made. The micrometer has been improved into an
instrument of great delicacy, and the number of doubles has swelled to
ten thousand; six hundred and fifty of them being known to be binary,
or revolving on orbits--Prof. S. W. Burnham, the distinguished young
astronomer of the Dearborn Observatory, Chicago, having discovered eight
hundred within the last eight years. This discovery implies stupendous
motion; every fixed star is a sun like our own, and we can imagine these
wheeling orbs to be surrounded by cool planets, the abode of life, as
well as ours. If the orbit of a binary system lies edgewise toward us,
then one star will hide the other each revolution, moving across it and
appearing on the other side. Several instances of this motion are
known; the distant suns having made more than a complete circuit since
discovery, the shortest periodic time known being twenty-five years.
Wonderful as was this achievement of the micrometer, one not less
surprising awaited its delicate measurement. If one walks in a long
street lighted with gas, the lights ahead will appear to separate, and
those in the rear approach. The little spider lines have detected just
such a movement in the heavens. The stars in Hercules are all the time
growing wider apart, while those in Argus, in exactly the opposite part
of the Universe, are steadily drawing nearer together. This demonstrates
that our sun with his stately retinue of planets, satellites, comets,
and meteorites, all move in grand march toward the constellation
Hercules. The entire universe is in motion. But these revelations of the
micrometer are tame compared with its final achievement, the discovery
of parallax.
This means difference of direction, and the parallax of a star is the
difference of its direction when viewed at intervals of six months.
Astronomers observe a star to-day with a powerful telescope and
micrometer; and in six months again measure the same star. But meanwhile
the earth has moved 183,000,000 miles to the east, so that if the star
has changed place, this enormous journey caused it, and the change
equals a line 91,400,000 miles long as viewed from the star. For years
many such observations were made; but behold the star was always in the
same place; the whole distance of the sun having dwindled down to the
diameter of a pin point in comparison with the awful chasm separating
us from the stars. Finally micrometers were made that measured lines
requiring 100,000 to make an inch; and a new series of observations
begun, crowning the labors of a century with success. Finite man
actually told the distance of the starry hosts and gauged the universe.
When the parallax of any object is found, its distance is at once known,
for the parallax is an arc of a circle whose radius is the distance.
By an important theorem in geometry it is learned, that when anything
subtends an angle of one second its distance is 206,265 times its
own diameter. The greatest parallax of any star is that of Alpha
Centauri--nine-tenths of a second; hence it is more than 206,265 times
91,400,000 miles--the distance of the sun--away, or twenty thousand
billions of miles. This is the distance of the nearest fixed star, and
is used as a standard of reference in describing greater depths of
space. This is not all the micrometer enables man to know, When the
distance separating the earth from two celestial bodies that revolve
is learned, the distance between the two orbs becomes known. Then
the period of revolution is learned from observation, and having the
distance and time, then their velocity can be determined. The distance
and velocity being given, then the combined weights of both suns can be
calculated, since by the laws of gravity and motion it is known how much
weight is required to produce so much motion in so much time, at so much
distance, and thus man weighs the stars. If the density of these bodies
could be ascertained, their diameters and volumes would be known, and
the size of the fixed stars would have been measured. Density can never
be exactly learned; but strange to say, photometers measure the quantity
of light that any bright body emits; hence the stars cannot have
specific gravity very far different from that of the sun, since they
send similar light, and in quantity obeying the law wherein light varies
inversely as the squares of distance. Therefore, knowing the weight and
having close approximation to density, the sizes of the stars are nearly
calculated. The conclusion is now made that all suns within the visible
universe are neither very many times larger nor smaller than our own.
(Newcomb and Holden's Astronomy, p. 454.)
Another result followed the use of the micrometer: the detection of the
proper motion of the stars. For several thousand years the stars have
been called "fixed," but the fine rulings of the filar micrometer tell a
different story. There are catalogues of several hundred moving stars,
whose motion is from one-half second to eight seconds annually. The
binary star, Sixty-one Cygni, the nearest north of the equator, moves
eight seconds every year, a displacement equal in three hundred and
sixty years to the apparent diameter of the moon. The fixed stars have
no general motion toward any point, but move in all directions.
Thus the micrometer revealed to man the magnitude and general structure,
together with the motions and revolutions of the sidereal heavens. Above
all, it demonstrated that gravity extends throughout the universe. Still
the longings of men were not appeased; they brought to view invisible
suns sunk in space, and told their weight, yet the thirst for knowledge
was not quenched. Men wished to know what all the suns are made of,
whether of substances like those composing the earth, or of kinds of
matter entirely different. Then was devised the spectroscope, and with
it men audaciously questioned nature in her most secluded recesses. The
basis of spectroscopy is the prism, which separates sunlight into seven
colors and projects a band of light called a spectrum. This was known
for three hundred years, and not much thought of it until Fraunhofer
viewed it with a telescope, and was surprised to find it filled with
hundreds of black lines invisible to the unaided eye. Could it be
possible that there are portions of the solar surface that fail to send
out light? Such is the fact, and then began a twenty years' search to
learn the cause. The lines in the solar spectrum were unexplained until
finally metals were vaporized in the intense heat of the electric arc
and the light passed through a spectroscope, when behold the spectra of
metals were filled with bright lines in the same places as were the
dark lines in the spectrum of the sun. Another step: if when metals are
volatilized in the arc, rays of light from the sun are passed through
the vapor and allowed to enter the spectroscope, a great change is
wrought; a reversal takes place, and the original black bands reappear.
A new law of nature was discovered, thus: "Vapors of all elements absorb
the same rays of light which they emit when incandescent." Every element
makes a different spectrum with lines in different places and of
different widths. These have been memorized by chemists, so that when an
expert having a spectroscope sees anything burn he can tell what it is
as well as read a printed page. Men have learned the alphabet of the
universe, and can read in all things radiating light, the constituent
elements. The black lines in the solar spectrum are there because in the
atmosphere of the sun exist vapors of metals, and the light from the
liquid metals below is unable to pass through and reach the earth, being
absorbed kind for kind. Gaseous iron sifts out all rays emitted from
melted iron, and so do the vapors of all other elements in the sun,
radiating light in unison with their own. Sodium, iron, calcium,
hydrogen, magnesium, and many other substances are now known to be
incandescent in the sun and stars; and the results of the developments
of the spectroscope may be summed up in the generalization that all
bodies in the universe are composed of the same substance the earth is.
The sun is subject to terrific hurricanes and cyclones, as well as
explosions, casting up jets to the height of 200,000 miles. In the early
days of spectroscopy these protuberances could only be seen at a time
of a total solar ellipse, and astronomers made long journeys to distant
parts of the earth to be in line of totality. Now all is changed. Images
of the sun are thrown into the observatory by an ingenious instrument
run by clockwork, and called a heliostat. This is set on the sun at such
an angle as to throw the solar image into the objective of the telescope
placed horizontally in a darkened observatory, and the pendulum ball set
in motion, when it will follow the sun without moving its image, all day
if desired. At the eye end of the telescope is attached the spectroscope
and the micrometer, and the whole set of instruments so adjusted that
just the edge of the sun is seen, making a half spectrum. The other half
of the spectroscope projects above the solar limb, and is dark, so if an
explosion throws up liquid jets, or flames of hydrogen, the astronomer
at once sees them and with the micrometer measures their height before
they have time to fall. And the spectrum at once tells what the jets are
composed of, whether hydrogen, gaseous iron, calcium, or anything else.
Prof. C. A. Young saw a jet of hydrogen ascend a distance of 200,000
miles, measured its height, noted its spectrum and timed its ascent by
a chronometer all at once, and was astonished to find the velocity one
hundred and sixty miles per second--eight times faster than the earth
flies on its orbit. By these improvements solar hurricanes, whirlpools,
and explosions can be seen from any physical observatory on clear days.
The slit of the spectroscope can be moved anywhere on the disk of the
sun; so that if the observer sees a tornado begin, he moves the slit
along with it, measures the length of its tract and velocity. With the
telescope, micrometer, heliostat, and spectroscope came desire for more
complex instruments, resulting in the invention of the photoheliograph,
invoking the aid of photography to make permanent the results of these
exciting researches. This mechanism consists of an excessively sensitive
plate, adjusted in the solar focus of the telespectroscope. In front
of the plate in the camera is a screen attached to a spring, and held
closed by a cord. The eye is applied to the spectroscopic end of the
complex arrangement to watch the development of solar hurricanes.
Finally an appalling outburst occurs; the flames leap higher and higher,
torn into a thousand shreds, presenting a scene that language is
powerless to describe. When the display is at the height of its
magnificence, the astronomer cuts the cord; the slide makes an exposure
of one-three thousandth part of a second, and an accurate photograph
is taken. The storm all in rapid motion is petrified on the plate;
everything is distinct, all the surging billows of fire, boilings, and
turbulence are rendered motionless with the velocity of lightning.
At Meudon, in France, M. Janssen takes these instantaneous photographs
of the sun, thirty inches in diameter, and afterward enlarges them to
ten feet; showing scenes of fiery desolation that appalls the human
imagination. (See address of Vice President Langley, A. A. A. S.,
Proceedings Saratoga Meeting, p. 56.) This huge photograph can be viewed
in detail with a small telescope and micrometer, and the crests of solar
waves measured. Many of these billows of fire are in dimensions
every way equal in size to the State of Illinois. Binary stars are
photographed so that in time to come they can be retaken, when if they
have moved, the precise amount can be measured.
Another instrument is the telepolariscope, to be attached to a
telescope. It tells whether any luminous body sends us its own, or
reflected light. Only one comet bright enough to be examined has
appeared since its perfection. This was Coggia's, and was found to
reflect solar from the tail, and to radiate its own light from the
nucleus.
Still another intricate instrument is in use, the thermograph, that
utilizes the heat rays from the sun, instead of the light. It takes
pictures by heat; in other words, it sees in the dark; brings invisible
things to the eye of man, and is used in astronomical and physical
researches wherein undulations and radiations are concerned. And now
comes the magnetometer, to measure the amount of magnetism that reaches
the earth from the sun. It points to zero when the magnetic forces of
the earth are in equilibrium, but let a magnetic storm occur anywhere
in the world and the pointer will move by invisible power. It detects a
close relation between the magnetism of the earth and sun. The needle is
deflected every time a solar disturbance takes place. At Kew, England,
an astronomer was viewing the sun with a telescope and observed a tongue
of flame dart across a spot whose diameter was thirty-three thousand
seven hundred miles. The magnetometer was violently agitated at once,
showing that whatever magnetism may be, its influence traversed the
distance of the sun with a velocity greater than that of light.
Not less remarkable is the new instrument, the thermal balance,
devised by Prof. S. P. Langley, Pittsburgh. It will measure the
one-fifty-thousandth part of a degree of heat, and consists of strips
of platinum one-thirty-second of an inch wide and one-fourth of an inch
long; and so thin that it requires fifty to equal the thickness of
tissue paper, placed in the circuit of electricity running to a
galvanometer. "When mounted in a reflected telescope it will record the
heat from the body of a man or other animal in an adjoining field, and
can do so at great distances. It will do this equally well at night,
and may be said, in a certain sense, to give the power of seeing in
the dark." (_Science_, issue of Jan. 8,1881, p. 12.) It is expected to
reveal great facts concerning the heat of the stars.
Indeed, the thermopile in the hands of Lockyer has already made palpable
the heat of the fixed stars. He placed the little detective in the focus
of a telescope and turned it on Arcturus. "The result was this, that the
heat received from Arcturus, when at an altitude of 55 deg., was found to be
just equal to that received from a cube of boiling water, three inches
across each side, at the distance of four hundred yards; and the heat
from Vega is equal to that from the same cube at six hundred yards."
(Lockyer's Star Gazing, p. 385.) Thus that inscrutable mode of force
heat traverses the depths of space, reaches the earth, and turns the
delicate balance of the thermopile. Another discovery was made with the
spectroscope; thus, if a boat moves up a river, it will meet more waves
than will strike it if going down stream. Light is the undulation of
waves; hence if the spectroscope is set on a star that is approaching
the earth, more waves will enter than if set on a receding star, which
fact is known by displacement of lines in the spectroscope from normal
positions. It is found that many fixed stars are approaching, while
others are moving away from the solar system.
We cannot note the researches of Edison, Lockyer, or Tyndall, nor of
Crookes, who has seemingly reached the molecules whence the universe is
composed.
The modern observatory is a labyrinth of sensitive instruments; and when
any disturbance takes place in nature, in heat, light, magnetism, or
like modes of force, the apparatus note and record them.
Men are by no means satisfied. Insatiable thirst to know more is
developing into a fever of unrest; they are wandering beyond the limits
of the known, every day a little farther. They survey space, and
interrogate the infinite; measure the atom of hydrogen and weigh suns.
Man takes no rest, and neither will he until he shall have found his own
place in the chain of nature.--_Kansas Review_.
* * * * *
THE FUTURE DEVELOPMENT OF ELECTRICAL APPLIANCES.
Prof. J. Perry lately delivered a lecture on this subject at the Society
of Arts, London, which contains in an epitomized form the salient points
of the hopes and fears of the more sanguine spirits of the electrical
world. Prof. Perry is one of the two professors who have been dubbed the
"Japanese Twins," and whose insatiate love of work induced one of our
most celebrated men of science to say that they caused the center of
experimental research to tend toward Tokyo instead of London. Professors
Ayrton and Perry have for some time been again resident in England, but
it is evident that they did not leave any of their energy in Japan, for
those who know them intimately, know that they are pursuing numerous
original investigations, and that so soon as one is finished, another
is commenced. It would have been difficult then to have found an abler
exponent of the future of electricity.
Prof. Perry, after referring to what might have been said of the great
things physical science has done for humanity, plunged into his subject.
The work to be done was vast, and the workers altogether out of
proportion to the task.
The methods of measurement of electricity are not generally understood.
Perhaps when electricity is supplied to every house in the city at a
certain price per horse power, and is used by private individuals for
many different purposes, this ignorance will disappear. Electrical
energy is obtained in various ways, but the generators get heated; and
one great object of inventors is to obtain from machines as much as
possible electrical energy of the energy in the first place supplied to
such machine. The lecturer called particular attention to the difference
between electricity and electrical energy, and attempted to drive home
the fundamental conceptions of electrical science by the analogies
derivable from hydraulics. A miller speaks not only of quantity of
water, but also of head of water. The statement then of quantity of
electricity is insufficient, except we know the electrical property
analogous to head of water, and which is termed electrical potential. A
small quantity of electricity of high potential is similar to a small
quantity of water at high level. The analogies between water and
electricity were collected in the form of a table shown on a wall sheet
as follows:
We Want to Use Water. We Want to Use Electricity.
1. Steam pump burns coal, 1. Generator burns zinc, or
and lifts water to a higher uses mechanical power, and
level. lifts electricity to a higher
level or potential.
2. Energy available is 2. Energy available is
amount of water lifted x amount of electricity x difference
difference of level. of potential.
3. If we let all the water 3. If we let all the electricity
flow away through channel flow through a wire from one
to lower level without doing screw of our generator to the
work, its energy is all other without doing work, all
converted into heat because the electrical energy is
of frictional resistance of converted into heat because of
pipe or channel. resistance of wire.
4. If we let water work a 4. If we let our electricity
hoist as well as flow through work a machine as well as
channels, less water flows flow through wires, less flows
than before, less power is than before, less power is
wasted in friction. wasted through the resistance
of the wire.
5. However long and narrow 5. However long and thin
may be the channels, the wires may be, electricity
water maybe brought from may be brought from any distance
distance, however great, however great, to give
to give out almost all its out almost all its original
original energy to a hoist. energy to a machine. This requires
This requires a great head a great difference of
and small quantity of water. potentials and a small current.
The difference between potential and electro-motive force was explained
thus: "difference of potential" is analogous with "difference of
pressure" or "head" of water, howsoever produced; whereas electromotive
force is analogous with the difference of pressure before and behind a
slowly moving piston of the pump employed by an unfortunate miller to
produce his water supply. Electricians have very definite ideas upon
the subject they are working at, and especial attention is paid to the
measurements on which their work depends. Examples of these measurements
were shown by the following tables on wall sheets:
ELECTRICAL MAGNITUDES (SOME RATHER APPROXIMATE).
Resistance of
One yard of copper wire, one-eighth
of an inch diameter...............................0.002 ohms.
One mile ordinary iron telegraph wire, .........10 to 20 "
Some of our selenium cells ............. 40 to 1,000,000 "
A good telegraph insulator ........... 4,000,000,000,000 "
Electro-motive force of
A pair of copper-iron junctions at a
difference of temperature of 1 deg. Fah......... =0.0000 volt.
Contact of zinc and copper ..................... =0.75 "
One Daniell's cell ............................. =1.1 "
Mr. Latimer Clark's standard cell .............. =1.45 "
One of Dr. De la Hue's batteries ...... =11,000 "
Lightning flashes probably many millions of volts.
Current measured by us in some experiments:
Using electrometer....... = almost infinitely small
currents.
Using delicate galvanometer =0.00,000,000,040 weber.
Current received from Atlantic
cable, when 25 words per minute
are being sent ................ = 0.000,001 weber
Current in ordinary land telegraph
lines ......................... = 0.003 weber
Current from dynamo machine.... = 5 to 100 weber
In any circuit, _current_ in webers = _electro-motive force_ in volts /
_resistance_ in ohms.
RATE OF PRODUCTION OF HEAT, CALCULATED IN THE SHAPE OF HORSE-POWER.
In the whole of a circuit=_current_ in webers x _electro-motive force_
in volts / 746. In any part of circuit=_current_ in webers x _difference
of potential_ at the two ends of the part of the circuit in question /
746. Or, =square of current in webers x resistance of the part in ohms /
746.
If there are a number of generators of electricity in a circuit, whose
electromotive forces in volts are E_1, E_2, etc., and if there are also
opposing electro-motive forces. F_1, F_2, etc., volts, and if C is the
current in webers, R the whole resistance of the current in ohms, P
the total horse-power taken at the generators, Q the total horse-power
converted into some other form of energy, and given out at the places
where there are opposing electro-motive forces, H the total horse-power
wasted in heat, because of resistance, then:
(E_1+E_2+etc.)-(F_1+F_2+etc.)
C = -----------------------------
R
[TEX: C = \frac{(E_1+E_2+\text{etc.})-(F_1+F_2+\text{etc.})}{R}]
C C
P = ---((E_1+E_2+etc.); Q = ---(F_1+F_2+etc.)
746 746
[TEX: \frac{C}{746}(E_1+E_2+\text{etc.});\ Q =
\frac{C}{746}(F_1+F_2+\text{etc.})]
C squared R
H = ----- .
746
[TEX: H = \frac{C^2 R}{746}.]
The lifting power of an electro-magnet of given volume is proportional
to the heat generated against resistance in the wire of the magnet.
The future of many electrical appliances depends on how general is the
public comprehension of the lessons taught by these wall sheets. If
a few capitalists in London would only spend a few days in learning
thoroughly what these mean, electrical appliances of a very distant
future would date from a few months hence.
A number of experiments were shown, in some of which electrical energy
was converted into heat, in others into sound, in others into work. At
this part of the lecture reference was made to the work of Prof. Ayrton
and his pupils at Cowper street (City and Guilds of London Institute
Classes). They measure (1) the gas consumed by the engine, (2) the
horse-power given to the dynamo machine, (3) the current in the
circuit in webers, and (4) the resistance of the circuit. Thus exact
calculations can now be made as to the horse power expended in any
part of the circuit, and the light given out in any given period by
an electric lamp. The dynamometers used in these measurements were
described, but at present, in some cases, the description given is for
various reasons incomplete, so that we shall take a future opportunity
of writing of these instruments. To measure the light a photometer,
constructed by Profs. Ayrton and Perry, is used, which obviates the
necessity of large rooms, and enables the operator to give the intensity
in a very short period of time. A number of measurements of the
illuminating power of an electric lamp were rapidly made during the
lecture with this photometer. By means of a small dynamo machine, driven
by an electric current generated in the Adelphi arches, a ventilator,
a sewing machine, a lathe, etc., were driven; in the latter a piece of
wood was turned. "What," said the lecturer, "do these examples show
you?" "They show that if I have a steam-engine in my back yard I can
transmit power to various machines in my house, but if you measured the
power given to these machines you would find it to be less than half
of what the engine driving the outside electrical machine gives out.
Further, when we wanted to think of heating of buildings and the boiling
of water, it was all very well to speak of the conversion of electrical
energy into heat, but now we find that not only do the two electrical
machines get heated and give out heat, but heat is given out by our
connecting wires. We have then to consider our most important question.
Electrical energy can be transmitted to a distance, and even to many
thousands of miles, but can it be transformed at the distant place into
mechanical or any other required form of energy, nearly equal in amount
to what was supplied? Unfortunately, I must say that hitherto the
practical answer made to us by existing machines is, 'No;' there is
always a great waste due to the heat spoken of above. But, fortunately,
we have faith in the measurements, of which I have already spoken, in
the facts given us by Joule's experiments and formulated in ways we can
understand. And these facts tell us that in electric machines of the
future, and in their connecting wires, there will be little heating, and
therefore little loss. We shall, I believe, at no distant date, have
great central stations, possibly situated at the bottom of coal-pits
where enormous steam engines will drive enormous electric machines. We
shall have wires laid along every street, tapped into every house, as
gas-pipes are at present; we shall have the quantity of electricity used
in each house registered, as gas is at present, and it will be passed
through little electric machines to drive machinery, to produce
ventilation, to replace stoves and fires, to work apple-parers and
mangles and barbers' brushes, among other things, as well as to give
everybody an electric light."
It is possible, as Prof. Ayrton first showed in his Sheffield lecture,
that electrical energy can be transmitted through long distances by
means of small wires, and that the opinion that wires of enormous
thickness would be required is erroneous. The desideratum required was
good insulation. He also showed that, instead of a limiting efficiency
of 50 per cent., the only thing preventing our receiving the whole of
our power was the mechanical friction which occurs in the machines. He
showed, in fact, how to get rid of electrical friction. A machine at
Niagara receives mechanical power, and generates electricity. Call this
the generator. Let there be Wires to another electric machine in New
York, which will receive electricity, and give out mechanical work.
Now this machine, which may be called the motor, produces a back
electromotive force, and the mechanical power given out is proportional
to the back electromotive force multiplied into the current. The
current, which is, of course, the same at Niagara as at New York, is
proportional to the difference of the two electromotive forces, and the
heat wasted is proportional to the square of the current. You see, from
the last table, that we have the simple proportion: power utilized is
to power wasted, as the back electromotive force of the motor is to the
difference between electromotive forces of generator and motor. This
reason is very shortly and yet very exactly given as follows:
Let electromotive force of generator be E; of motor F. Let total
resistance of circuit be R. Then if we call P the horse-power received
by the generator at Niagara, Q, the horse-power given out by motor
at New York, that is, utilized; H, the horse-power wasted as heat in
machines and circuit; C, the current flowing through the circuit:
C=(E-F) / R
P=E(E-F) / (746 R)
Q=F(E-F) / (746 R)
H=(E-F)_2 / (746 R)
Q:H::F:E-F
The water analogy was again called into play in the shape of a model
for the better demonstration of the problem. The defects in existing
electric machines and the means of increasing the E.M.F. were discussed,
the conclusions pointing to the future use of very large machines and
very high velocities. The future of telephonic communication received a
passing remark, and attention called to the future of electric railways.
The small experiments of Siemens have determined the ultimate success of
this kind of railway. Their introduction is merely a question of time
and capital. The first cost of electric railways would be smaller than
that of steam railways; the working expenses would also be reduced.
The rails would be lighter, the rolling stock lighter, the bridges and
viaducts less costly, and in the underground railways the atmosphere
would not be vitiated.
"About two years ago, it struck Professor Ayrton and myself, when
thinking how very faint musical sounds are heard distinctly from the
telephone, in spite of loud noises in the neighborhood, that there
was an application of this principle of recurrent effects of far more
practical importance than any other, namely, in the use of musical notes
for coast warnings in thick weather. You will say that fog bells and
horns are an old story, and that they have not been particularly
successful, since in some states of the weather they are audible, in
others not.
"Now, it seems to be forgotten by everybody that there is a medium of
communicating with a distant ship, namely, the water, which is not at
all influenced by changes in the weather. At some twenty or thirty feet
below the surface there is exceedingly little disturbance of the water,
although there may be large waves at the surface. Suppose a large
water-siren like this--experiment shown--is working at as great a depth
as is available, off a dangerous coast, the sound it gives out is
transmitted so as to be heard at exceedingly great distances by an ear
pressed against a strip of wood or metal dipping into the water. If the
strip is connected with a much larger wooden or metallic surface in the
water the sound is heard much more distinctly. Now, the sides of a ship
form a very large collecting surface, and at the distance of several
miles from such a water siren as might be constructed, we feel quite
sure that, above the noise of engines and flapping sails, above the far
more troublesome noise of waves striking the ship's side, the musical
note of the distant siren would be heard, giving warning of a dangerous
neighborhood. In considering this problem, you must remember that
Messrs. Colladon and Sturn heard distinctly the sound of a bell struck
underwater at the distance of nearly nine miles, the sound being
communicated by the water of Lake Geneva."
The next portion of the lecture discussed the great value of a rapid
recurrence of effects, the obtaining of sound by means of a rapid
intermission of light rays on selenium joined up in an electric circuit
being instanced as an example. Then recent experiments on the refractive
power of ebonite were detailed--the rough results tending to give
greater weight to Clerk-Maxwell's electro-magnetic theory of light. The
index of refraction of ebonite was found by Profs. Ayrton and Perry to
be roughly 1.7. Clerk-Maxwell's theory requires that the square of this
number should be equal to the electric specific inductive capacity of
the substance. For ebonite this electric constant varies from 2.2 to 3.5
for different specimens, the mean of which is almost exactly equal to
the square of 1.7.
* * * * *
RESEARCHES ON THE RADIANT MATTER OF CROOKES AND THE MECHANICAL THEORY OF
ELECTRICITY.
By DR. W. F. GINTL, abstracted by DR. VON GERICHTEN.
The author discusses the question whether, according to the experiments
of Crookes, the assumption of an especial fourth state of aggregation is
necessary, or whether the facts may be satisfactorily explained without
such hypothesis? He shows that the latter alternative is possible with
the aid of a mechanical theory of electricity. If the radiant matter
produced in the vacuum is a phenomenon _sui generis,_ produced by the
action of electricity and heat upon the molecules of gas remaining in
the receiver, it is, in the first place, doubtful to apply to it the
conception of an aggregate condition. The author considers it impossible
to form a clear understanding of the phenomena in accordance with the
theory of Crookes, or to find in the facts any evidence of the existence
of radiant matter. An explanation of the latter phenomenon is thus
given: Particles become separated from the surface of the substance of
the negative pole, they are repelled, and they move away from the pole
with a speed resulting from the antagonistic forces in a parallel and
rectilinear direction, preserving their speed and their initial path so
long as they do not meet with obstacles which influence their movement.
At a certain density of the gases present in the exhausted space, these
particles, in consequence of the impact of gaseous molecules more or
less opposed to their direction of movement, lose their velocity after
traveling a short distance and soon come to rest. The more dilute the
gas the smaller is the number of the impacts of the gaseous molecules
encountering the molecules of the poles, and at a certain degree of
dilution the repelled polar particles will be able to traverse the space
open to them without any essential alteration in their speed, the small
number of the existing gaseous molecules being no longer able to retard
the molecules of the polar no their journey through the apparatus. The
luminous phenomena of the Geissler tubes the author supposes to be
produced by the intense blows which the gaseous molecules receive from
the polar molecules flying rapidly through the apparatus. The intensity
of the luminous phenomena will naturally decrease with the number of
the photophorous particles occupying the space. Accordingly in the
experiments of Crookes, on continued rarefaction of the gas, a condition
was reached where a display of light is no longer perceptible, or can be
made visible merely by the aid of fluorescent bodies. A condition may
also appear, as is shown by Crookes' experiment, with the metallic plate
intercalated as negative pole in the middle of. a Geissler tube, with
the positive poles at the ends. In this case the gaseous molecules are,
so to speak, driven away by the polar particles endowed with an equal
initial velocity, till at a certain distance from the pole the mass of
the gaseous molecules and their speed become so great that a luminous
display begins. In an analogous manner the author explains the phenomena
of phosphorescence which Crookes' elicits by the action of his radiant
matter. In like manner the thermic and the mechanical effects are most
simply explained, according to the expression selected by Crookes
himself, as the results of a "continued molecular bombardment." The
attraction of the so called radiant matter, regarded as a stream of
metallic particles by the magnet, will not appear surprising.
* * * * *
ECONOMY OF THE ELECTRIC LIGHT.
Mr. W. H. Preece writes to the _Journal of Arts_ as follows:
At the South Kensington Museum, very careful observations have been made
on the relative cost of the two systems, _i. e._, gas and electricity.
The court lighted is that known as the "Lord President's" (or the Loan)
Court. It is 138 feet long by 114 feet wide, and has an average height
of about 42 feet. It is divided down the middle lengthwise by a central
gallery. There are cloisters all around it on the ground floor, and the
walls above are decorated in such a way that they do not assist in the
reflection or diffusion of the light. The absence of a ceiling--the
court being sky-lighted--is to some extent compensated for by drawing
the blinds under the sky-lights.
The experiments commenced about twelve months ago, with eight lamps
only on one side of the court. The system was that of Brush. The dynamo
machine was driven by an eight horse-power Otto gas engine, supplied by
Messrs. Crossley. The comparison with the gas was so much in favor of
electricity, and the success of the experiment so encouraging, that it
was determined to light up the whole court.
The gas engine, which was not powerful enough, was replaced by a
14-horse power "semi-portable" steam engine, by Ransomes & Co., of
Ipswich--an engine of sufficient power to drive double the required
number of lights. The dynamo machine is a No. 7 Brush. There are sixteen
lamps in all--eight on each side of the court. The machine has given no
trouble whatever, and it has, as yet, shown no signs of wear. The
lamps were not all good, and it was found that they required careful
adjustment, but when once they were got to go right they continued to
do so, and have, up to the present, shown no signs of deterioration,
although the time during which they have been in operation is nine
months.
The first outlay has been as follows:
Engine and fixing, including shafting and
belting................................ L420
Dynamo machine......................... 400
Lamps, apparatus, and conducting wire . 384
------
L1,204
The cost of working has been, from June 22, to December 31, during which
period the lights were going on 87 nights for a total time of 359 hours:
L s. d.
Carbons............................... 18 9 0
Oil, etc.............................. 4 11 6
Coal.................................. 11 14 0
Wages................................. 34 7 6
----------
L69 2 0
being at the rate of 3s. 10d. per hour of light.
Now, the consumption of gas in the court would have been 4,800 cubic
feet per hour, which, at 3s. 4d. per 1,000 cubic feet, would amount to
16s. per hour, thus showing a saving of working expenses of 12s. 2d. per
hour, or, since the museum is lit up for 700 hours every year, a total
saving at the rate of L426 per annum.
In estimating the cost as applied to this court, only half the cost of
the engine should be taken, for a second dynamo machine has lately been
added to light up some of the picture galleries, and the "Life" room of
the Art School. The capital outlay should, therefore, be L994. In making
a fair estimate of the annual cost, we should also allow something for
percentage on capital, and something for wear and tear. Take--
L s.
5 per cent, on the capital............................. 49 10
5 per cent, for wear and tear of electrical apparatus.. 39 0
5 per cent, for depreciation of engines, etc........... 21 0
-------
Total.......... L109 10
leaving a handsome balance to the good of L316 10s. as against gas. The
results of the working, both practically and financially, have proved to
be, at South Kensington, a decided success.
I am indebted to Colonel Festing, R.E., who has charge of the lighting,
for these details.
The same comparison cannot be made at the British Museum, for no gas was
used in the reading-room before the introduction of the electric light,
but the cost of lighting has proved to be 5s. 6d. per hour--at least
one-third of that which would be required for gas. The system in use
at the Museum is Siemens', the engine being by Wallis and Steevens, of
Basingstoke.
"An excellent example of economic electric lighting, is that of Messrs.
Henry Tate & Sons, sugar refinery, Silvertown. A small Tangye engine,
placed under the supervision of the driver of a large engine of the
works, drives an 'A' size 'Gramme' machine, which feeds a 'Crompton' 'E'
lamp. This is hung at a height of about 12 feet from the ground in a
single story shed, about 80 feet long, and 50 feet wide, and having an
open trussed roof. The light, placed about midway, lengthways, has a
flat canvas frame, forming a sort of ceiling directly over it, to help
to diffuse the illumination. The whole of the shed is well lit; and a
large quantity of light also penetrates into an adjoining one of similar
dimensions, and separated by a row of columns. The light is used
regularly all through the night, and has been so all through the winter.
Messrs. Tate speak highly of its efficiency. To ascertain the exact cost
of the light, as well as of the gas illumination which it replaced, a
gas-meter was placed to measure the consumption of the gas through
the jets affected; and also the carbons consumed by the electric
illumination were noted. A series of careful experiments showed that
during a winter's night of 14 hours' duration the illumination by
electricity cost 1s. 9d., while that by gas was 3s. 6d., or 11/2d. per
hour against 3d. per hour. To this must be added the greatly increased
illumination, four to five times, given by the electric light, to the
benefit of the work; while this last illuminant also allowed, during the
process of manufacture of the sugar, the delicate gradations of tint
to be detected; and so to avoid those mistakes, sometimes costly ones,
liable to arise through the yellow tinge of gas illumination. This alone
would add much to the above-named economy, arising from the use of
electric illumination in sugar works."
I am indebted for these facts to Mr. J. N. Shoolbred, under whose
supervision the arrangements were made.
Some excellent experience has been gained at the shipbuilding docks in
Barrow-in-Furness, where the Brush system has been applied to illuminate
several large sheds covering the punching and shearing machinery,
bending blocks, furnaces, and other branches of this gigantic business.
In one shed, which was formerly lighted by large blast-lamps, in which
torch oil was burnt, costing about 5d. per gallon, and involving an
expenditure of L8 9s. per week, the electric light has been adopted at
an expenditure of L4 14s. per week.
The erecting shop, 450 feet by 150 feet, formerly dimly lit by gas at a
cost of L22 per week, is now efficiently lit by electricity at half the
cost.
I am indebted for these facts to Mr. Humphreys, the manager of the
works.
The Post office authorities have contracted with Mr. M. E. Crompton,
to light up the Post-office at Glasgow for the same price as they have
hitherto paid for gas, and there is no doubt that in many instances this
arrangement will leave a handsome profit to the Electric Light Company.
They are about to try the Brockie system in the telegraph galleries,
and the Brush system in the newspaper sorting rooms of the General
Post-office in St. Martin's-le-Grand.
* * * * *
ON THE SPACE PROTECTED BY A LIGHTNING-CONDUCTOR.
By WILLIAM HENRY PREECE.
[Footnote: From the _Philosophical Magazine_ for December, 1880.]
Any portion of non-conducting space disturbed by electricity is called
an electric field. At every point of this field, if a small electrified
body were placed there, there would be a certain resultant force
experienced by it dependent upon the distribution of electricity
producing the field. When we know the strength and direction of this
resultant force, we know all the properties of the field, and we can
express them numerically or delineate them graphically, Faraday (Exp.
Res., Sec. 3122 _et seq._) showed how the distribution of the forces in any
electric field can be graphically depicted by drawing lines (which he
called _lines of force_) whose direction at every point coincides with
the direction of the resultant force at that point; and Clerk-Maxwell
(Camb. Phil. Trans., 1857) showed how the magnitude of the forces can
be indicated by the way in which the lines of force are drawn. The
magnitude of the resultant force at any point of the field is a function
of the potential at that point; and this potential is measured by the
work done in producing the field. The potential at any point is, in
fact, measured by the work done in moving a unit of electricity from the
point to an infinite distance. Indeed the resultant force at any point
is directly proportional to the rate of fall of potential per unit
length along the line of force passing through that point. If there be
no fall of potential there can be no resultant force; hence if we take
any surface in the field such that the potential is the same at every
point of the surface, we have what is called an _equipotential surface._
The difference of potential between any two points is called an
electromotive force. The lines of force are necessarily perpendicular to
the surface. When the lines of force and the equipotential surfaces are
straight, parallel, and equidistant, we have a _uniform field._ The
intensity of the field is shown by the number of lines passing through
unit area, and the rate of variation of potential by the number of
equipotential surfaces cutting unit length of each line of force. Hence
the distances separating the equipotential surfaces are a measure of the
electromotive force present. Thus an electric field can be mapped or
plotted out so that its properties can be indicated graphically.
[Illustration: Fig. 1]
The air in an electric field is in a state of tension or strain; and
this strain increases along the lines of force with the electromotive
force producing it until a limit is reached, when a rent or split occurs
in the air along the line of least resistance--which is disruptive
discharge, or lightning.
[Illustration: Fig. 2]
Since the resistance which the air or any other dielectric opposes to
this breaking strain is thus limited, there must be a certain rate of
fall of potential per unit length which corresponds to this resistance.
It follows, therefore, that the number of equipotential surfaces per
unit length can represent this limit, or rather the stress which leads
to disruptive discharge. Hence we can represent this limit by a
length. We can produce disruptive discharge either by approaching the
electrified surfaces producing the electric field near to each other, or
by increasing the quantity of electricity present upon them; for in each
case we should increase the electromotive force and close up, as it
were, the equipotential surfaces beyond the limit of resistance. Of
course this limit of resistance varies with every dielectric; but we are
now dealing only with air at ordinary pressures. It appears from
the experiments of Drs. Warren De La Rue and Hugo Muller that the
electromotive force determining disruptive discharge in air is about
40,000 volts per centimeter, except for very thin layers of air.
[Illustration: Fig. 3]
If we take into consideration a flat portion of the earth's surface, A
B (fig. 1), and assume a highly charged thunder-cloud, C D, floating at
some finite distance above it, they would, together with the air, form
an electrified system. There would be an electric field; and if we take
a small portion of this system, it would be uniform. The lines, a b,
a' b'...would be lines of force; and cd, c' d', c" d' ...would be
equipotential planes. If the cloud gradually approached the earth's
surface (Fig. 2), the field would become more intense, the equipotential
surfaces would gradually close up, the tension of the air would increase
until at last the limit of resistance of the air, _e f_, would be
reached; disruptive discharge would take place, with its attendant
thunder and lightning. We can let the line, _e f_, represent the limit
of resistance of the air if the field be drawn to scale; and we can thus
trace the conditions that determine disruptive discharge.
[Illustration: Fig. 4]
If the earth-surface be not flat, but have a hill or a building, as H or
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