THE MODE OF SOLAR ENERGY.
But is there such an available force? There is one, and only
one,--electricity, when properly generated and suitably applied. It
is an axiom of electrical science that any fluid which will at all
conduct a current of electricity can be decomposed by a current of
electricity. (See Urbanitsky's work, "Electricity in the Service of
Man," Cassell's edition, page 154.) It is there stated (page 152),
"We have frequently had occasion to mention certain chemical effects
of electricity,--namely, the decomposition of gaseous compounds
into simple gases." Page 157, "Whatever the substances we expose
to the action of the galvanic current, decomposition takes place
proportional to the strength of the current." Page 152, "Hydrogen is
always evolved at the negative pole of the battery and oxygen at the
positive pole. The gases can then be collected in different tubes,
the hydrogen tube receiving twice as much gas as the oxygen tube;
since water consists of two volumes of hydrogen and one volume
of oxygen, it follows that the galvanic current decomposes water
into its constituents. As chemically pure water has so great a
resistance as almost to force us to consider it a non-conductor,
it is generally acidulated with sulphuric acid. The smallest amount
of acid diminishes the resistance considerably. The silent discharge
is far more effective in bringing about this transformation than the
spark discharge." Page 37, "Gases are bad conductors of electricity;
if it had been otherwise, we should never have become acquainted with
electricity, as it would have been conducted away by the air as fast
as it was generated. The vacuum also does not conduct electricity,
but moist air becomes a partial conductor. Moist air also will spoil
the insulation of non-conducting supports. All bodies are more or
less hygroscopic, and the moisture condensed on their surfaces thus
turns the best insulators into conductors. Change of temperature also
influences conductivity." Page 63, "When using induction machines, the
moisture of the air often causes experiments to fail, especially before
large audiences. The atmosphere becomes saturated with moisture, and
it is often impossible to get the machine in working order." Several
desiccating devices are mentioned by the authors of this work, as
used with such machines, to prevent such dissipation or conduction
of electricity from the machine into space by the aqueous vapor of
the atmosphere. In describing the aurora borealis (page 93), these
authors say, "The rarefied air is nearer the earth at the poles than
the equator, in consequence of the earth's centrifugal motion, and,
the earth being negatively electrified, negative electricity will flow
from this point, directed against the positively electrified upper
layers of rarefied air." Same work, pages 127, 128, "The resistance
(in liquids) diminishes as the temperature increases, a result which
is exactly opposite to what occurs with metals. Conductivity for
carbon increases with the temperature, thus agreeing with the action
of liquids." Page 133, "To determine the resistance in liquids,
the above methods cannot be employed, liquids being decomposed by
the electrical current." Referring to the voltaic arc and the spark
of the induction apparatus (page 200), it is said, "Dry air under
great pressure offers a high resistance, but a perfect vacuum is a
perfect insulator, and between these extremes there are degrees of
rarification which admit of a flow of electricity." In general, it
is said that electrical decomposition requires that the electrolyte
be in liquid form, but this is not universally true, and throughout
interplanetary space may not be true at all. In Ferguson's work on
Electricity, it is stated that, "The passage of electricity through
compound gases in a state of great rarity, as in the so-called vacuum
tubes, frequently separates them up into their constituents." So, also,
the opinion that electricity cannot be readily conducted through
dry gases is refuted by the play of the auroral streamers. The
distance from the surface of the earth of these electrical waves
and the auroral arch is variously estimated at from seventy to two
hundred and sixty-five miles, and in one instance "at a height of
from four thousand to six thousand miles;" see article in Appleton's
Cyclopædia. Certainly there could be no sensible moisture at the
temperatures there prevalent, and especially at night and during the
fall and winter months when these displays are very frequent. Whether
the currents be due to induction, as between neighboring bodies one of
which is electrified, or from direct emission, as in brush discharges,
there must obviously be some medium of contact and continuity for
the free transference of electrical energy through space. Regarding
the rationale of electrolysis ("Electricity in the Service of
Man"), after discussing certain other theories, the authors say,
"Clausius, too, assumes an electrified condition of the molecules
of each electrode, but he neither attributes to the galvanic current
the force of direction nor power of decomposing. He points out that
both the molecules of fluids and also their atoms are in continual
motion. The atoms in molecules of fluids are held together but by a
moderate force, and the molecules themselves constantly undergo changes
both of synthesis and analysis. The galvanic current merely effects a
regulated motion of the atoms; the positive ions are attracted by the
negative electrode, and the negative ions by the positive electrode,
and by this means are separated out from the liquid." Page 91, "The
upper layers of air are more or less electrified, so as to have a
potential differing from that of the earth, but how their electrical
condition has been produced is not at present known. Condensation of
water-vapor is supposed to produce electricity. Close to the earth
the air has little or no electricity; the farther from the earth
the greater the amount of electricity in the air." Referring to the
sparking discharge, it is said, page 75, "The density of the air,
however, has to be taken into account; the sparking distance is
lessened in denser air, and becomes greater when the atmospheric
pressure is diminished. Not only the density, but also the chemical
composition of the medium influences the sparking distance. Faraday
found the distances considerably less in chlorine gas, but twice
as long in hydrogen gas as in air." Page 74, "The sparking distance
increases at a somewhat greater rate than the difference of potential
of the discharging bodies.... When the sparking distance becomes very
great ... it is proportional to the difference of potential." Page 91,
"There is a difference of potential between the earth and points in the
air above. In fine weather the potential is higher the higher we go,
increasing usually at the rate of twenty to forty volts for each foot."
It will be seen that, continued upward at this rate, the increased
electrical pressure for each mile of elevation would be between 100,000
and 200,000 volts, or for each one hundred miles more than 10,000,000
volts; and at an altitude of one thousand miles, if carried so far,
the potential would be between one and two hundred million volts,
an electrical pressure quite inconceivable to us. Such a potential
in currents of enormous quantity continually flowing from the earth
to the sun would certainly decompose any aqueous vapors condensed
around these bodies. But the question at once arises, What reason
is there to suppose that such currents could possibly flow between
the earth and the sun, across that vast intervening region of space,
a distance of more than 90,000,000 miles? And would not the resistance
to such currents in transit be so enormous that the entire potential,
however great, would have been practically lost long before reaching
the sun? To this there is a complete and irrefutable answer, not
based upon any abstract theory, but upon established fact. It is an
absolute certainty that electrical currents of enormous quantity and
high potential are constantly passing between the earth and the sun,
and that these currents have so free a passage--far more free than
through any metallic circuits that we know of--that they pass over
this enormous distance absolutely without appreciable resistance. We
may note in this connection the well-known facts, now being largely
utilized, though the art is still in its infancy, of telegraphing and
transmitting all sorts of electrical currents over large distances
without wires or any conductors, except those furnished by nature.
Of the currents between the earth and the sun, Professor Proctor,
in his "Light Science for Leisure Hours," says, "Remembering the
influence which the sun has been found to exercise upon the magnetic
needle, the question will naturally arise, Has the sun anything to do
with magnetic storms? We have clear evidence that he has. On the 1st of
September, 1859, Messrs. Carrington and Hodgson were observing the sun,
one at Oxford and the other in London. Their scrutiny was directed to
certain large spots which at that time marked the sun's face. Suddenly
a bright light was seen by each observer to break out on the sun's
surface and to travel, slowly in appearance, but in reality at the rate
of about seven thousand miles in a minute, across a part of the solar
disk. Now, it was found afterwards that the self-registering magnetic
instruments at Kew had made at that very instant a strongly-marked
jerk. It was learned that at that moment a magnetic storm prevailed
in the West Indies, in South America, and in Australia. The signal
men in the telegraph stations at Washington and Philadelphia received
strong electric shocks; the pen of Bain's telegraph was followed by
a flame of fire; and in Norway the telegraphic machinery was set on
fire. At night great auroras were seen in both hemispheres. It is
impossible not to connect these startling magnetic indications with
the remarkable appearance observed upon the sun's disk. But there is
other evidence. Magnetic storms prevail more commonly in some years
than in others. In those years in which they occur most frequently
it is found that the ordinary oscillations of the magnetic needle
are more extensive than usual. Now, when these peculiarities had been
noticed for many years, it was found that there was an alternate and
systematic increase and diminution in intensity of magnetic action,
and that the period of the variation was about eleven years. But at
the same time a diligent observer had been recording the appearance
of the sun's face from day to day and from year to year. He had
found that the solar spots are in some years more freely displayed
than in others, and he had determined the period in which the spots
had successively presented with maximum frequency to be about eleven
years. On a comparison of the two sets of observations it was found
(and has now been placed beyond a doubt by many years of continual
observation) that magnetic perturbations are most energetic when the
sun is most spotted, and vice versa. For so remarkable a phenomenon
as this none but a cosmical cause can suffice. We can neither say
that the spots cause the magnetic storms nor that the magnetic storms
cause the spots. We must seek for a cause producing at once both sets
of phenomena." It will be observed that the phenomena seen in the sun
were marked at the same instant by violent electric perturbations on
earth. Hence something must have passed with the velocity of light,
which we know to be at the rate of 188,000 miles per second, or in
about eight minutes from the sun to the earth. But it is stated in
"Electricity in the Service of Man," page 82, that, "According to the
theoretical calculations of Kirchhoff, as well as of Ayrton and Perry,
the velocity of electricity in a wire without resistance would be
equal to the velocity of light." Hence we perceive that the apparent
difficulty has vanished in the light of observed fact, and that
currents of electricity do pass and are constantly passing between
the earth and the sun without the slightest loss of speed,--that
is to say, without resistance. We shall find in the sequel that the
above phenomena were caused most probably by a partial interruption
of a constant direct current from the earth to the sun, instead of
by an opposite return current from the sun to the earth. In further
illustration of the above facts we quote the following, page 172,
"Electricity in the Service of Man:" "Many attempts have been made
to find a connection between the spots and prominences in the sun and
the electrical phenomena on the earth. Professor Forster says that by
numerous magnetic observations of the last thirty or forty years it
has been proved that the formation of black spots on the surface of
the sun, and the generation of pillars and clouds of glowing gases
in the immediate neighborhood of the sun, stand in close connection
with certain deviations in direction and intensity of the earth's
magnetic forces." Professor Proctor, in his "Light Science for Leisure
Hours," says, "From all this it appears, incontestably, that there
is an intimate connection between the causes of auroras and those
of terrestrial magnetism.... The magnetic needle not only swayed
responsively to auroras observable in the immediate neighborhood,
but to auroras in progress hundreds and thousands of miles away. Nay,
as inquiry progressed, it was discovered that the needles in our
northern observatories are swayed by influences associated even with
the occurrence of auroras around the southern polar regions.... Could
we only associate auroras with terrestrial magnetism, we should
still have done much to enhance the interest which the beautiful
phenomenon is calculated to excite. But when once this association
has been established, others of even greater interest are brought
into recognition; for terrestrial magnetism has been clearly shown
to be influenced directly by the action of the sun.... We already
begin to see, then, that auroras are associated in some mysterious
way with the action of the solar rays. The phenomenon which had been
looked on for so many ages as a mere spectacle, caused perhaps by some
process in the upper regions of the air of a simple local character,
has been brought into the range of planetary phenomena. As surely as
the brilliant planets which deck the nocturnal skies are illuminated
by the same orb which gives us our days and seasons, so are they
subject to the same mysterious influence which causes the northern
banners to wave respondently over the starlit depths of heaven. Nay,
it is even probable that every flicker and coruscation of our auroral
displays correspond with similar manifestations upon every planet
which travels round the sun." In Professor Ball's late work, "In the
High Heavens," the author says, "Dr. Schuster suggests that there may
be an electric connection between the sun and the planets. In fact,
with some limitations, we might even assert that there must be such a
connection. It is well known that great outbreaks on the sun have been
immediately followed, I might almost say accompanied, by remarkable
magnetic disturbances on the earth. The instances that are recorded
of this connection are altogether too remarkable to be set aside as
mere coincidences. Dr. Huggins has not referred in this connection
to Hertz's astonishing discoveries; but it seems quite possible that
research along this line may throw light on the subject, at present so
obscure, of the electric relation between the sun and the earth." Of
this common electrical relationship between our sun and the different
planets, and of these with each other, Professor Proctor says, in
his article, "Terrestrial Magnetism," "Interesting as are the bonds
of union which Copernicus and Kepler and Newton have traced in the
relations of our system, it would seem as though we were approaching
the traces of a yet more wonderful law of association. We see the
earth's magnetism responding to the solar influences, not merely
in those rhythmic motions which belong to the periodic variations,
but in sudden thrills affecting the whole framework of our globe. The
magnetic storms which are called into action by such solar disturbances
as the one of September, 1859, are, we may feel sure, not peculiar
to our own earth. The other planets feel the same influence,--not,
perhaps, in exactly the same way, but according to the constitution
and physical habitudes which respectively belong to them. So that one
can scarce conceive a subject of study at once more promising and more
interesting." Of these prophetic shadows which science often seems to
cast before, Professor Nichol, in his "Architecture of the Heavens"
(referring to Sir William Herschel), says, "Without difficulty or
pretence he there casts aside an idea which had not been questioned
before, unless in a few of those obscure, indefinite speculations
which, strangely enough, often prelude important discoveries." These
facts are thus incontestably established: that electric currents of
enormous energy and vast quantity are constantly passing without
appreciable resistance and with the speed of light between the
earth and the sun; that such currents cannot be conducted through
vacua, or through dry gases, or through a dense medium; and that,
whatever other matter may exist in the intervening space, such space
is pervaded throughout by an attenuated vapor of such constitution
and density that it will transmit such electrical currents with the
highest conceivable efficiency. We know that such passage of these
currents cannot depend upon the ether of space which is acted upon by
the sun to produce the ethereal undulatory vibrations of light and
heat, for, after we have produced the most perfect vacuum possible,
we find that the rays of light continue to pass through it as freely
as they pass through space, while currents of electricity cannot be
made to pass at all. Hence we know to a certainty that the medium
which transmits these enormous currents of electricity must be a vapor
capable of conducting electricity, that it must hence be decomposable
by the electric current, and that when decomposed one of its elements
must consist of hydrogen gas and the other of oxygen; in other words,
that this conducting medium must consist of attenuated aqueous vapor,
commingled doubtless with other vapors which themselves, like the acid
of the acidulated water used in electrolysis, aid in the conduction
of these enormous currents. We also know that such vapors in space
will be necessarily attracted, by gravitation, around the solar and
planetary bodies immersed therein, and must form condensed vaporous
atmospheres or cloud masses, and if these are decomposed by the passage
of such currents of electricity, that hydrogen gas will be liberated
at the solar galvanic pole and oxygen at the terrestrial or other
planetary pole, precisely as we find to be the case in nature. Will
such gaseous envelopes, then, have the same temperature for each
gas when thus liberated, or will the hydrogen envelope of the sun be
heated to incandescence, due to the passage of the electrical current?
The temperature of interplanetary space is probably very low. Of this
Professor Ball says, "What this may be is a matter of some uncertainty,
but from all the evidence available it seems plain that we may put it
at not less than three hundred degrees below zero;" and the same author
adds, "The temperature is taken to be sixty-four degrees below zero,
being presumably that at the confines of the atmosphere." Whatever
the temperature of space, or its variations, may be, the passage of
the planetary electricity through the condensed hydrogen envelope of
the sun will produce great changes in the heat of that body and of
the solar core within. While with a small electrolytic apparatus we
find no special differences of temperature in the gases, with large
quantities of electricity, driven at a high potential, we find that
a new and startling result ensues. Something of this sort is seen
in the operation of electric arc-light lamps, now in common use,
in which two slightly separated carbon points are traversed by a
current of considerable potential. The current is driven across the
intervening space between the points, carrying with it an atmosphere
of disintegrated carbon, through which the electricity is carried
at its highest speed, and a most brilliant light is produced. In
"Electricity in the Service of Man," page 151, it is said, "We may
conclude from this that the current does not cease when the arc
of light is formed. The resistance of the arc seems to be only very
slight; in fact, the current must be conducted by it." Of the structure
and constitution of the luminous electrosphere, or arc, produced in
these lamps, "Professor J. A. Fleming," says the Scientific American,
"has shown that the well-known color of the light of the electric
arc from carbon points is due to the incandescence of the carbon
filling the space between the positive and the negative rods. The true
arc is here, and exists in a space filled with the vapor of carbon,
which has a brilliant violet color. Examined by the spectroscope, the
central axis of the carbon arc gives a spectrum marked by two bright
violet bands. Outside this is an aureole of carbon vapor of yellow or
golden color. The electrical strain of the arc occurs chiefly at the
surface of the crater which forms at the end of the positive rod,
where, in fact, the principal work of generating light is done;
for eighty per cent. of the total light of the arc comes from the
incandescent carbon at this place. Thus, in a sense, the arc light is
mainly an incandescent light, the effect being produced by the layer of
carbon which is being constantly evaporated at an extremely elevated
temperature. Hence the light of the carbon arc is not, and can never
be, white, as it is sometimes described as being, but must always be
tinted violet by the carbon vapor normally present between the rods."
The significance of the above-quoted extract will be readily perceived
when we come to consider the action of the direct planetary electrical
currents upon the solar envelope, the effects in both cases being
substantially identical. The quantity and intensity of the electric
current, as it passes through the incandescent arc to the negative
pole, and thence back to the dynamo, are diminished exactly in
proportion to the energy expended in the generation of the light
and heat of the arc. It is precisely the same as in the operation
of a turbine water-wheel; if working at its highest efficiency, the
discharged water is almost deprived of force: its gravity has been
converted into work. In the electric light this conversion is only
partial, owing to atmospheric and other conditions; but in the case
of the solar envelope and its core, it is nearly, if not altogether,
perfect, so that the currents of electricity are almost entirely
converted into light and heat, or expended in the electrolytic
decomposition of the surrounding aqueous vapors, and do not reappear
as electricity, but as converted solar energy. Brilliant, however,
as the light rays are in a powerful arc lamp,--perhaps the nearest
to solar light we can produce,--the obscure heat rays are far more
numerous and powerful. On page 476 of the work just cited a table is
given, showing the proportion of visible and invisible rays emitted
by different illuminants, and with the electric lamp, even, ninety per
cent. of all the rays emitted by the voltaic arc are heat rays, which
are obscure and invisible. But the startling effects of electricity
of large quantity and high potential, in the decomposition of water,
are far more strikingly exhibited by an apparatus shown in 1893 at the
Chicago Exhibition by a firm from Brussels, and which is described
in the Electrical Review as follows: "An ordinary wooden pail is
three-quarters filled with water slightly acidulated; a lead plate
about nine inches broad by sixteen inches long dips to the bottom of
the pail and is connected to an incandescent dynamo machine capable of
giving over one hundred and fifty ampères. The iron rod, or article to
be heated, is connected to the pole of the dynamo and simply dipped
into the water; it immediately becomes heated and rapidly rises to a
melting temperature; only that portion of the metal completely immersed
becomes heated, and the heating is so rapid that neither the water nor
that portion of the metal out of the water becomes very warm. Wrought
iron and steel actually melt if long enough held under water. A carbon
rod subjected to this process becomes amorphous carbon, proving that
a temperature of at least four thousand degrees Centigrade has been
reached, and it is stated that with two hundred and twenty volts'
pressure a temperature of eight thousand degrees Centigrade has been
reached. There are various theories to account for this phenomenon,
but from close observation it appears to be a case of arc heating. The
moment the metal is plunged into the water it is enveloped in hydrogen
gas decomposed from the water. This envelope of gas parts the water and
metal, forming an arc, which raises the surrounding gaseous envelope
to an enormous temperature; the metal surrounded by this arc is almost
immediately raised to the same temperature. A flame of burning hydrogen
appears around the metal on the surface of the water. The principle of
the method is the same as that on which the burning of an arc light
between two carbon points under water depends. An arc lamp will burn
quite steadily under water if the connections are made water-proof;
the arc itself requires no protection."
It will be seen that the process above described is precisely
analogous to that involved in the problem of the sun's energy. The
planets correspond with the leaden plates, upon which oxygen is
disengaged from the water, while at the same moment the liberated
hydrogen necessarily appears at the opposite pole. The generation
of hydrogen gas forms an envelope or atmosphere of hydrogen around
the sun which forces back the aqueous vapor. The current, in passing
through this gaseous envelope to the metal core within, intensely
heats the hydrogen, which rapidly communicates its rising heat to the
central core. If this core is composed of metals, and the temperature
be raised sufficiently high, which only depends upon the quantity and
working pressure of the electricity employed, the metal core will be
volatilized in whole or in part, and, if of mixed metals, we will
find the presence of these elements revealed in the spectroscopic
lines corresponding thereto, and the flames and flashes of hydrogen
at the surfaces beyond the envelope, at the surface of contact with
the matter of space, will be also seen. In fact, such an experiment,
properly prepared, could be made to show roughly most of the phenomena
of solar light and heat as they actually appear, such as sun-spots,
prominences, jets, plumes, faculæ, the photosphere, chromosphere,
absorption bands, vortical disturbances, metallic vapors, and the
complete solar spectrum, with the different Fraunhofer lines. In
the case of the sun, these currents must be measured by millions of
ampères, and possibly by hundreds of millions of volts, instead of by
mere hundreds, while the hydrogen envelope extends outward from the
sun's surface hundreds of thousands of miles until, perhaps, finally
merged into the corona. As the currents pass from the planets and
planetoids (for not only the larger planets, but all the planetary
bodies of our system must contribute, if any of them contribute) to
the sun, or rather to the sphere of its electrical action, without
resistance, so long as these planets generate constant currents of the
same, or nearly the same, potential, so long will the sun maintain
his constant light and heat; if these are increased or diminished,
the sun's light and heat will be temporarily, but only temporarily,
increased or diminished; and this process must continue, without
further loss or change, indefinitely into the future. Whatever the
sun may gain by increment of meteoric masses may pass for what it
is worth, but the gradual contraction of his volume cannot proceed
while his present temperature is maintained by the passage of such
currents,--that is to say, his light and heat will remain constant,
and also his mass and volume, so long as the electric currents which
pass from the planets to the sun and the constitution of space which
surrounds the sun and planets themselves remain constant.
It now remains to consider how such enormous currents of electricity
can be generated and maintained. We know, of course, that chemical
changes cannot operate to produce them. They must be derived from
something contained in or diffused through interplanetary space,
and the planets themselves must be the means by which such currents
of electricity are brought into effective operation. On our own
earth we have many kinds of mechanically-constructed electrical
apparatus which generate electricity, to use a popular expression,
or which, more properly, separate the opposite potentials from
an unstable electrical tension or equilibrium of the matter of
space. These machines practically take positive electricity from
the mutually-balanced electric potentials of which the earth and
its surrounding gaseous envelope are the vast common storehouse,
in such manner that the positive electricity thus drawn out from and
again passing into the common storehouse shall, during such transit,
be compelled to pass through channels which will cause it to do work,
at the expense of its potential or pressure, during its passage,
or in which electricity is raised in its electro-motive force from
a lower to a higher potential or pressure, just as the pressure of
water is increased when delivered from a greater or a still greater
height, or steam, when confined in space under higher and still higher
temperatures. But none of these machines actually generate electricity
ab initio; they merely put into effective operation the pre-existing
force. The mass of the earth is of irregularly negative polarity, the
air above is positive, and as we ascend, the potential, or voltage,
or pressure increases at a nearly uniform rate of from twenty to forty
volts for each foot. The earth is thus surrounded by an electrosphere
as well as an atmosphere, and the two are not coincident, for while
the pressure of the atmosphere diminishes as we ascend, that of the
electrosphere increases. The moon, too, and each planet must have
its electrosphere, and around the sun's core we can see the solar
electrosphere in its visible glory. Thus, all our planets rotate upon
their axes and revolve around the sun, each surrounded by an enormous
electrosphere, just as an electrical induction machine is surrounded,
when in operation, with an electrosphere of its own, and which,
by breaking connection with the conductor which carries away its
current, becomes, when shown in a darkened room, clearly visible. In
"Electricity in the Service of Man" it is said, page 63, "The inductive
action of the machine is quite as rapid and as powerful when both
collectors are removed and nothing is left but the two rotating
disks and their respective contact or neutralizing brushes. The whole
apparatus then bristles with electricity, and if viewed in the dark
presents a most beautiful appearance, being literally bathed with
luminous brush discharges." This is a true aurora.
Let us now examine some of these more recent electric machines,--the
later induction, not the older frictional machines, for it is
obvious that the rotation of the planets, if they operate as
electric generators, or separators, must act by induction and not by
friction. The frictional machines are of the old type and are well
known from the books; in these a glass disk or cylinder is rubbed
upon in its rotation by an amalgamated (so called) friction pad fixed
securely to the bed of the machine. But more recently these have
been replaced by far more powerful and simple machines which operate
entirely by induction, like approaching thunderclouds, for instance,
and in which one or more glass disks are merely rotated rapidly and
freely in the air, these disks having a number of light metallic
sectors, such as bits of tin-foil, pasted on their outer sides at
equal radial intervals, and with metallic collecting brushes which,
however, barely graze the surfaces of the rotating disk. There is
no pressure and no friction, except that of the disks as they freely
revolve in the atmosphere.
In the above-quoted work, page 61, is a description of Wimshurst's
influence machine, one of the most recent and most powerful, which we
condense as follows: This machine was produced about 1883. It consists
of two circular disks of thin glass fourteen and one-half inches in
diameter in the sample described, attached at their centers to loose
bosses, so as to be rotated by cords and pulleys operated by a handle,
in opposite directions. The disks rotate parallel with each other and
are not more than one-eighth of an inch apart, and have their surfaces
well varnished; and attached by cement to their outer surfaces are
twelve or more radial, sector-shaped plates of thin brass- or tin-foil,
disposed around the disks at equal distances apart. These sectors
take the place of the "inductors" of Holtz's instrument, and appear
to act also as carriers, though the exact nature of their action is
somewhat mysterious. It appears, however, probable that those acting
for the time as carriers on the one disk act at the same time as
inductors on the other. The two sectors on the same diameter of each
disk, at opposite sides of the center, are twice in each revolution
momentarily placed in metallic connection with one another by means of
a pair of fine wire brushes attached to the ends of a bent metal rod
loosely pivoted at the center of each disk, the metal sectors just
grazing the tips of the wire brushes as they pass. There is one of
these bent rods on the outside of each disk, and their position as
pivoted on their center can be varied at will, both with reference
to the one on the opposite side and to the position of the fixed
collecting combs. The efficiency of the machine varies with their
position, and the maximum appears to be generally when the brushes
touch the disks on diameters crossing the position of the collecting
combs at about forty-five degrees, and with the bent rods on opposite
sides at right angles to each other. The collecting combs are simple
forks with collecting points turned inward, which forks embrace the
opposite sides of the disks outside, which freely rotate between them,
and they are supported on insulated posts. These supports may be small
Leyden jars or condensers, with discharging knobs, or may be connected
with similar condensers at a distance, or arranged in batteries or
otherwise. The presence of the collecting combs is not necessary to
the operation of the machine, their sole function being to carry away
the positive electricity as generated. The machine is self-exciting,
and it is believed that the initial action must be due to friction in
the layer of air contained between the plates, which, as above stated,
are only about one-eighth of an inch apart. It is nearly independent
of atmospheric conditions, and not liable to reverse its polarity,
as are the Voss machines. The Voss machine uses a larger glass disk
which does not rotate, but is fixed, and which has a central opening
three inches wide, with a different arrangement of tin-foil disks or
sectors, and a smaller glass disk rotates parallel with it. The Holtz
machine is somewhat similar, using a single rotating, well-varnished
glass disk revolving opposite a well-varnished larger disk, the latter
provided with three sector-shaped openings or windows, with varnished
paper inductors or flaps passing through these windows so as to touch
the revolving disk. There are also two series of fine metal points held
by brass bars provided with insulated handles and discharging knobs.
It is only necessary to give a general idea of the construction and
operation of such machines, as their specific construction can be
readily learned from the books. Of the mode of operation, however,
it is said, "What takes place when the machine is in action is of
a very complicated nature, and can hardly be said to be perfectly
understood." With a Wimshurst machine having disks of a diameter
of fourteen and one-half inches "there is produced under ordinary
atmospheric conditions a powerful spark discharge between the knobs
when they are separated by a distance of four and one-half inches,
a pint size Leyden jar being in connection with each knob (one on each
opposite diameter of the two disks), and these four-and-one-half-inch
discharges take place in regular succession at every two and a half
turns of the handle. It is usual to construct the machine with small
Leyden jars or condensers attached to conductors, by which the spark
is materially increased. A machine has been constructed with plates
seven feet in diameter, which, it was believed, would give sparks
thirty inches long; but no Leyden jars have been found to withstand
its discharge, all being pierced by the enormous tension." Three
of Toepler's induction machines (see page 59, "Electricity in the
Service of Man"), connected together, gave a current which maintained
a platinum wire one-fifth of a millimeter thick continually at a red
heat, and was also capable of decomposing water.