[Footnote: Aug. Guerout in _La Lurmière Electrique_.]
An endeavor has often been made to carry the origin of the electric
telegraph back to a very remote epoch by a reliance on those more or
less fanciful descriptions of modes of communication based upon the
properties of the magnet.
It will prove not without interest before entering into the real history
of the telegraph to pass in review the various documents that relate to
the subject.
In continuation of the 21st chapter of his _Magia naturalis_, published
in 1553, J. B. Porta cites an experiment that had been made with the
magnet as a means of telegraphing. In 1616, Famiano Strada, in his
_Prolusiones Academicæ_, takes up this idea, and speaks of the
possibility of two persons communicating by the aid of two magnetized
needles influenced by each other at a distance. Galileo, in _Dialogo
intorno_, written between 1621 and 1632 and Nicolas Caboeus, of Ferrara,
in his _Philosophia magnetica_, both reproduce analogous descriptions,
not however without raising doubts as to the possibility of such a
system.
A document of the same kind, to which great importance has been attached
is found in the _Recreations mathematiques_ published at Rouen in 1628,
under the pseudonym of Van Elten, and reprinted several times since,
with the annotations and additions of Mydorge and Hamion and which must,
it appears, be attributed to the Jesuit Leurechon. In his chapter on the
magnet and the needles that are rubbed therewith, we find the following
passage.
"Some have pretended that, by means of a magnet or other like stone,
absent persons might speak with one another. For example, Claude being
at Paris, and John at Rome, if each had a needle that had been rubbed
with some stone, and whose virtue was such that in measure as one needle
moved at Paris the other would move just the same at Rome, and if Claude
and John each had an alphabet, and had agreed that they would converse
with each other every afternoon at 6 o'clock, and the needle having made
three and a half revolutions as a signal that Claude, and no other,
wished to speak to John, then Claude wishing to say to him that the king
is at Paris would cause his needle to move, and stop at T, then at H,
then at E, then at K, I, N, G and so on. Now, at the same time, John's
needle, according with Claude's, would begin to move and then stop at
the same letters, and consequently it would be easily able to write or
understand what the other desired to signify to it. The invention is
beautiful, but I do not think there can be found in the world a magnet
that has such a virtue. Neither is the thing expedient, for treason
would be too frequent and too covert."
The same idea was also indicated by Joseph Glanville in his _Scepsis
scientifica_, which appeared in 1665, by Father Le Brun, in his
_Histoire critique des pratiques superstitieuses_, and finally by the
Abbé Barthelemy in 1788.
The suggestion offered by Father Kircher, in his _Magnes sive de arte
magnetica_, is a little different from the preceding. The celebrated
Jesuit father seeks however, to do nothing more than to effect a
communication of thoughts between two rooms in the same building. He
places, at short distances from each other, two spherical vessels
carrying on their circumference the letters of the alphabet, and each
having suspended within it, from a vertical wire a magnetized figure. If
one of these latter he moved, all the others must follow its motions,
one after the other, and transmission will thus be effected from the
first vessel to the last. Father Kircher observes that it is necessary
that all the magnets shall be of the same strength, and that there shall
be a large number of them, which is something not within the reach
of everybody. This is why he points out another mode of transmitting
thought, and one which consists in supporting the figures upon vertical
revolving cylinders set in motion by one and the same cord hidden with
in the walls.
There is no need of very thoroughly examining all such systems of
magnetic telegraphy to understand that it was never possible for them to
have a practical reality, and that they were pure speculations which it
is erroneous to consider as the first ideas of the electric telegraph.
We shall make a like reserve with regard to certain apparatus that
have really existed, but that have been wrongly viewed as electric
telegraphs. Such are those of Comus and of Alexandre. The first of these
is indicated in a letter from Diderot to Mlle. Voland, dated July 12,
1762. It consisted of two dials whose hands followed each other at a
distance, without the apparent aid of any external agent. The fact
that Comus published some interesting researches on electricity in the
_Journal de Physique_ has been taken as a basis for the assertion that
his apparatus was a sort of electrical discharge telegraph in which the
communication between the two dials was made by insulated wires hidden
in the walls. But, if it be reflected how difficult it would have been
at that epoch to realize an apparatus of this kind, if it be remembered
that Comus, despite his researches on electricity, was in reality only a
professor of physics to amuse, and if the fact be recalled that cabinets
of physics in those days were filled with ingenious apparatus in which
the surprising effects were produced by skillfully concealed magnets, we
shall rather be led to class among such apparatus the so-called "Comus
electric telegraph."
We find, moreover, in Guyot's _Recreations physiques et
mathematiques_--a work whose first edition dates back to the time at
which Comus was exhibiting his apparatus--a description of certain
communicating dials that seem to be no other than those of the
celebrated physicist, and which at all events enables us to understand
how they worked.
Let one imagine to himself two contiguous chambers behind which ran
one and the same corridor. In each chamber, against the partition that
separated it from the corridor, there was a small bracket, and upon the
latter, and very near the wall, there was a wooden dial supported on a
standard, but in no wise permanently fixed upon the bracket. Each dial
carried a needle, and each circumference was inscribed with twenty-five
letters of the alphabet. The experiment that was performed with these
dials consisted in placing the needle upon a letter in one of the
chambers, when the needle of the other dial stopped at the same letter,
thus making it possible to transmit words and even sentences. As for the
means of communication between the two apparatus, that was very simple:
One of the two dials always served as a transmitter, and the other as a
receiver. The needle of the transmitter carried along in its motion
a pretty powerful magnet, which was concealed in the dial, and which
reacted through the partition upon a very light magnetized needle that
followed its motions, and indicated upon an auxiliary dial, to a person
hidden in the corridor, the letter on which the first needle had been
placed. This person at once stepped over to the partition corresponding
to the receiver, where another auxiliary dial permitted him to properly
direct at a distance the very movable needle of the receiver. Everything
depended, as will be seen, upon the use of the magnet, and upon a deceit
that perfectly accorded with Comus' profession. There is, then, little
thought in our opinion that if the latter's apparatus was not exactly
the one Guyot describes, it was based upon some analogous artifice.
Jean Alexandre's telegraph appears to have borne much analogy with
Comus'. Its inventor operated it in 1802 before the prefect of
Indre-et-Loire. As a consequence of a report addressed by the prefect of
Vienne to Chaptal, and in which, moreover, the apparatus in question was
compared to Comus', Alexandre was ordered to Paris. There he refused to
explain upon what principle his invention was based, and declared that
he would confide his secret only to the First Consul. But Bonaparte,
little disposed to occupy himself with such an affair, charged Delambre
to examine it and address a report to him. The illustrious astronomer,
despite the persistence with which Alexandre refused to give up his
secret to him, drew a report, the few following extracts from which
will, we think, suffice to edify the reader:
"The pieces that the First Consul charged me to examine did not contain
enough of detail to justify an opinion. Citizen Beauvais (friend and
associate of Alexandre) knows the inventor's secret, but has promised
him to communicate it to no one except the First Consul. This
circumstance might enable me to dispense with any report; for how judge
of a machine that one has not seen and does not know the agent of? All
that is known is that the _telegraphe intime_ consists of two like
boxes, each carrying a dial on whose circumference are marked the
letters of the alphabet. By means of a winch, the needle of one dial is
carried to all the letters that one has need to use, and at the same
instant the needle of the second box repeats, in the same order, all the
motions and indications of the first.
"When these two boxes are placed in two separate apartments, two persons
can write to and answer one another, without seeing or being seen by one
another, and without any one suspecting their correspondence. Neither
night nor fog can prevent the transmission of a dispatch.... The
inventor has made two experiments--one at Portiers and the other at
Tours--in the presence of the prefects and mayors, and the record shows
that they were fully successful. To-day, the inventor and his associate
ask that the First Consul be pleased to permit one of the boxes to be
placed in his apartment and the other at the house of Consul Cambaceres
in order to give the experiment all the _éclat_ and authenticity
possible; or that the First Consul accord a ten minutes' interview to
citizen Beauvais, who will communicate to him the secret, which is
so easy that the simple _expose_ of it would be equivalent to a
demonstration, and would take the place of an experiment.... If, as one
might be tempted to believe from a comparison with a bell arrangement,
the means adopted by the inventor consisted in wheels, movements,
and transmitting pieces, the invention would be none the less
astonishing.... If, on the contrary, as the Portier's account seems to
prove, the means of communication is a fluid, there would be the more
merit in his having mastered it to such a point as to produce so regular
and so infallible effects at such distances.... But citizen Beauvais
... desires principally to have the First Consul as a witness and
appreciator.... It is to be desired, then, that the First Consul shall
consent to hear him, and that he may find in the communication that will
be made to him reasons for giving the invention a good reception and for
properly rewarding the inventor."
But Bonaparte remained deaf, and Alexandre persisted in his silence, and
died at Angers, in 1832, in great poverty, without having revealed his
secret.
As, in 1802, Volta's pile was already invented, several authors have
supposed an application of it in Alexandre's apparatus. "Is it not
allowable to believe," exclaims one of these, "that the electric
telegraph was at that time discovered?" We do not hesitate to respond in
the negative. The pile had been invented for too short a time, and too
little was then known of the properties of the current, to allow a
man so destitute of scientific knowledge to so quickly invent all the
electrical parts necessary for the synchronic operation of the two
needles. In this _telegraphe intime_ we can only see an apparatus
analogous to the one described by Guyot, or rather a synchronism
obtained by means of cords, as in Kircher's arrangement. The fact that
Alexandre's two dials were placed on two different stories, and distant,
horizontally, fifteen meters, in nowise excludes this latter mode of
transmission. On another hand, the mystery in which Alexandre was
shrouded, his declaration relative to the use of a fluid, and the
assurance with which he promised to reveal his secret to the First
Consul, prove absolutely nothing, for too often have the most profoundly
ignorant people--the electric girl, for example--befooled learned bodies
by the aid of the grossest frauds. From the standpoint of the history
of the electric telegraph, there is no value, then, to be attributed to
this apparatus of Alexandre, any more than there is to that of Comus or
to _any_ of the dreams based upon the properties of the magnet.
The history of the electric telegraph really begins with 1753, the date
at which is found the first indication of a telegraph truly based upon
the use of electricity. This telegraph is described in a letter written
by Renfrew, dated Feb. 1, 1753, and signed with the initials "C.M.,"
which, in all probability, were those of a savant of the time--Charles
Marshall. A few extracts from this letter will give an idea of the
precision with which the author described his invention:
"Let us suppose a bundle of wires, in number equal to that of the
letters of the alphabet, stretched horizontally between two given
places, parallel with each other and distant from each other one inch.
"Let us admit that after every twenty yards the wires are connected to a
solid body by a juncture of glass or jeweler's cement, so as to prevent
their coming in contact with the earth or any conducting body, and so
as to help them to carry their own weight. The electric battery will be
placed at right angles to one of the extremities of the wires, and the
bundle of wires at each extremity will be carried by a solid piece of
glass. The portions of the wires that run from the glass support to the
machine have sufficient elasticity and stiffness to return to their
primitive position after having been brought into contact with the
battery. Very near to this same glass support, on the opposite side,
there descends a ball suspended from each wire, and at a sixth or a
tenth of an inch beneath each ball there is placed one of the letters of
the alphabet written upon small pieces of paper or other substance light
enough to be attracted and raised by the electrified ball. Besides this,
all necessary arrangements are taken so that each of these little papers
shall resume its place when the ball ceases to attract.
[Illustration: FIG. 1.--LESAGE'S TELEGRAPH.]
"All being arranged as above, and the minute at which the correspondence
is to begin having been fixed upon beforehand, I begin the conversation
with my friend at a distance in this way: I set the electric machine
in motion, and, if the word that I wish to transcribe is 'Sir,' for
example, I take, with a glass rod, or with any other body electric
through itself or insulating, the different ends of the wires
corresponding to the three letters that compose the word. Then I press
them in such a way as to put them in contact with the battery. At the
same instant, my correspondent sees these different letters carried in
the same order toward the electrified balls at the other extremity of
the wires. I continue to thus spell the words as long as I judge proper,
and my correspondent, that he may not forget them, writes down the
letters in measure as they rise. He then unites them and reads the
dispatch as often as he pleases. At a given signal, or when I desire it,
I stop the machine, and, taking a pen, write down what my friend sends
me from the other end of the line."
The author of this letter points out, besides, the possibility of
keeping, in the first place, all the springs in contact with the
battery, and, consequently, all the letters attracted, and of indicating
each letter by removing its wire from the battery, and consequently
making it fall. He even proposed to substitute bells of different sounds
for the balls, and to produce electric sparks upon them. The sound
produced by the spark would vary according to the bell, and the letters
might thus be heard.
Nothing, however, in this document authorizes the belief that Charles
Marshall ever realized his idea, so we must proceed to 1774 to find
Lesage, of Geneva, constructing a telegraph that was based upon the
principle indicated twenty years before in the letter of Renfrew.
The apparatus that Lesage devised (Fig. 1) was composed of 24 wires
insulated from one another by a non conducting material. Each of these
wires corresponded to a small pith ball suspended by a thread. On
putting an electric machine in communication with such or such a one of
these wires, the ball of the corresponding electrometer was repelled,
and the motion signaled the letter that it was desired to transmit. Not
content with having realized an electric telegraph upon a small scale,
Lesage thought of applying it to longer distances.
"Let us conceive," said he in a letter written June 22, 1782, to Mr.
Prevost, of Geneva, "a subterranean pipe of enameled clay, whose cavity
at about every six feet is separated by partitions of the same material,
or of glass, containing twenty-four apertures in order to give passage
to as many brass wires as these diaphragms are to sustain and keep
separated. At each extremity of this pipe are twenty-four wires that
deviate from one another horizontally, and that are arranged like the
keys of a clavichord; and, above this row of wire ends, are distinctly
traced the twenty-four letters of the alphabet, while beneath there is a
table covered with twenty-four small pieces of gold-leaf or other easily
attractable and quite visible bodies."
Lesage had thought of offering his secret to Frederick the Great; but
he did not do so, however, and his telegraph remained in the state of a
curious cabinet experiment. He had, nevertheless, opened the way, and,
dating from that epoch, we meet with a certain number of attempts at
electrostatic telegraphy. [1]
[Footnote 1: Advantage has been taken of a letter from Alexander Volta
to Prof. Barletti (dated 1777), indicating the possibility of firing his
electric pistol from a great distance, to attribute to him a part in the
invention of the telegraph. We have not shared in this opinion, which
appears to us erroneous, since Volta, while indicating the possibility
above stated, does not speak of applying such a fact to telegraphy.]
The first in date is that of Lemond, which is spoken of by Arthur Young
(October 16, 1787), in his _Voyage Agronomique en France_:
"In the evening," says he, "we are going to Mr. Lemond's, a very
ingenious mechanician, and one who has a genius for invention.... He has
made a remarkable discovery in electricity. You write two or three words
upon paper; he takes them with him into a room and revolves a machine
within a sheath at the top of which there is an electrometer--a pretty
little ball of feather pith. A brass wire is joined to a similar
cylinder, and electrified in a distant apartment, and his wife on
remarking the motions of the ball that corresponds, writes down the
words that they indicate; from whence it appears that he has formed an
alphabet of motions. As the length of the wire makes no difference in
the effect, a correspondence might be kept up from very far off, for
example with a besieged city, or for objects much more worthy of
attention. Whatever be the use that shall be made of it, the discovery
is an admirable one."
And, in fact, Lemond's telegraph was of the most interesting character,
for it was a single wire one, and we already find here an alphabet based
upon the combination of a few elementary signals.
The apparatus that next succeeds is the electric telegraph that Reveroni
Saint Cyr proposed in 1790, to announce lottery numbers, but as to the
construction of which we have no details. In 1794 Reusser, a German,
made a proposition a little different from the preceding systems, and
which is contained in the _Magazin für das Neueste aus der Physik und
Naturgeschichte_, published by Henri Voigt.
"I am at home," says Reusser, "before my electric machine, and I am
dictating to some one on the other side of the street a complete
letter that he is writing himself. On an ordinary table there is fixed
vertically a square board in which is inserted a pane of glass. To this
glass are glued strips of tinfoil cut out in such a way that the spark
shall be visible. Each strip is designated by a letter of the alphabet,
and from each of them starts a long wire. These wires are inclosed in
glass tubes which pass underground and run to the place whither the
dispatch is to be transmitted. The extremities of the wires reach a
similar plate of glass, which is likewise affixed to a table and
carries strips of tinfoil similar to the others. These strips are also
designated, by the same letters, and are connected by a return wire with
the table of him who wishes to dictate the message. If, now, he who is
dictating puts the external armature of a Leyden jar in contact with the
return wire, and the ball of this jar in contact with a metallic rod
touching that of the tinfoil strip which corresponds with the letter
which he wishes to dictate to the other, sparks will be produced upon
the nearest as well as upon the remotest strips, and the distant
correspondent, seeing such sparks, may immediately write down the letter
marked. Will an extended application of this system ever be made? That
is not the question; it is possible. It will be very expensive; but the
post hordes from Saint Petersburg to Lisbon are also very expensive,
and if any one should apply the idea on a large scale, I shall claim a
recompense."
Every letter, then, was signaled by one or several sparks that started
forth on the breaking of the strip; but we see nothing in this document
to authorize the opinion which has existed, that every tinfoil strip was
a sort of magic tablet upon which the sparks traced the very form of the
letter to be transmitted.
Voigt, the editor of the _Magazin_, adds, in continuation of Reusser's
communication: "Mr. Reusser should have proposed the addition to this
arrangement of a vessel filled with detonating gas which could be
exploded in the first place, by means of the electric spark, in order
to notify the one to whom something was to be dictated that he should
direct his attention to the strips of tinfoil."
This passage gives the first indication of the use of a special call for
the telegraph. The same year (1794), in a work entitled _Versuch über
Telegraphie und Telegraphen_, Boeckmann likewise proposed the use of the
pistol as a call signal, in conjunction with the use of a line composed
of two wires only, and of discharges in the air or a vacuum, grouped in
such a way as to form an alphabet.
Experiments like those indicated by Boeckmann, however, seem to have
been made previous to 1794, or at that epoch, at least, by Cavallo,
since the latter describes them in a _Treatise on Electricity_ written
in English, and a French translation of which was published in 1795.
In these experiments the length of the wires reached 250 English feet.
Cavallo likewise proposed to use as signals combustible or detonating
materials, and to employ as a call the noise made by the discharge of a
Leyden jar.
In 1796 occurred the experiments of Dr. Francisco Salva and of the
Infante D. Antonio. The following is what we may read on this subject in
the _Journal des Sciences_:
"Prince de la Paix, having learned that Dr. Francisco Salva had read
before the Royal Academy of Sciences of Barcelona a memoir on the
application of electricity to telegraphy, and that he had presented at
the same time an electric telegraph of his own invention, desired
to examine this machine in person. Satisfied as to the accuracy and
celerity with which we can converse with another by means of it, he
obtained for the inventor the honor of appearing before the king. Prince
de la Paix, in the presence of their majesties and of several lords,
caused the telegraph to converse to the satisfaction of the whole court.
The telegraph conversed some days afterward at the residence of the
Infante D. Antonio.
"His Highness expressed a desire to have a much completer one that
should have sufficient electrical power to communicate at great
distances on land and sea. The Infante therefore ordered the
construction of an electric machine whose plate should be more than
forty inches in diameter. With the aid of this machine His Highness
intends to undertake a series of useful and curious experiments that he
has proposed to Dr. D. Salva."
In 1797 or '98 (some authors say 1787), the Frenchman, Betancourt, put
up a line between Aranjuez and Madrid, and telegraphed through the
medium of discharges from a Leyden jar.
But the most interesting of the telegraphs based upon the use of static
electricity is without doubt that of Francis Ronalds, described by the
latter, in 1823, in a pamphlet entitled _Descriptions of an Electrical
Telegraph and of some other Electrical Apparatus_, but the construction
of which dates back to 1816.
What is peculiarly interesting in Ronalds' apparatus is that it presents
for the first time the use of two synchronous movements at the two
stations in correspondence.
The apparatus is represented in Fig. 2. It is based upon the
simultaneous working of two pith-ball electrometers, combined with the
synchronous running of two clock-work movements. At the two stations
there were identical clocks for whose second hand there had been
substituted a cardboard disk (Fig. 3), divided into twenty sectors. Each
of these latter contained one figure, one letter, and a conventional
word. Before each movable disk there was a screen, A (Fig. 2),
containing an aperture through which only one sector could, be seen at
a time. Finally, before each screen there was a pith-ball electrometer.
The two electrometers were connected together by means of a conductor
(C) passing under the earth, and which at either of its extremities
could be put in communication with either an electric machine or the
ground. A lever handle, J, interposed into the circuit a Volta's pistol,
F, that served as a call.
When one of the operators desired to send a dispatch to the other he
connected the conductor with the machine, and, setting the latter in
operation, discharged his correspondent's pistol as a signal. The call
effected, the first operator continued to revolve the machine so that
the balls of pith should diverge in the two electrometers. At the same
time the two clocks were set running. When the sender saw the word
"attention" pass before the slit in the screen he quickly discharged the
line, the balls of the two electrometers approached each other, and, if
the two clocks agreed perfectly, the correspondent necessarily saw in
the aperture in his screen the same word, "attention." If not, he moved
the screen in consequence, and the operation was performed over until
he could send, in his turn, the word "ready." Afterward, the sender
transmitted in the same way one of the three words, "letters,"
"figures," "dictionary," in order to indicate whether he wished to
transmit letters or figures, or whether the letters received, instead of
being taken in their true sense, were to be referred to a conventional
vocabulary got up in advance. It was after such preliminaries that the
actual transmission of the dispatch was begun. The pith balls, which
were kept constantly apart, approached each other at the moment the
letter to be transmitted passed before the aperture in the screen.
Ronalds, in his researches, busied himself most with the construction of
lines. He put up on the grounds near his dwelling an air line 8 miles
long; and, to do so, stretched fine iron wire in zigzag fashion between
two frames 18 meters apart. Each of these frames carried thirty-seven
hooks, to which the wire was attached through the intermedium of silk
cords. He laid, besides, a subterranean line of 525 feet at a depth of 4
feet. The wire was inclosed within thick glass tubes which were placed
in a trough of dry wood, of 2 inch section, coated internally and
externally with pitch. This trough was, moreover, filled full of pitch
and closed with a cover of wood. Ronalds preferred these subterranean
conductors to air lines. A portion of one of them that was laid by him
at Hammersmith figured at the Exhibition of 1881, and is shown in Fig.
4.
Nearly at the epoch at which Ronalds was experimenting in England,
a certain Harrisson Gray Dyar was also occupying himself with
electrostatic telegraphy in America. According to letters published only
in 1872 by American journals, Dyar constructed the first telegraph in
America. This line, which was put up on Long Island, was of iron wire
strung on poles carrying glass insulators, and, upon it, Dyar operated
with static electricity. Causing the spark to act upon a movable disk
covered with litmus paper, he produced by the discoloration of the
latter dots and dashes that formed an alphabet.
[Illustration: FIG. 2.]
These experiments, it seems, were so successful that Dyar and his
relatives resolved to construct a line from New York to Philadelphia;
but quarrels with his copartners, lawsuits, and other causes obliged him
to leave for Rhode Island, and finally for France in 1831. He did not
return to America till 1858.
Dyar, then, would seem to have been the first who combined an alphabet
composed of dots and dashes. On this point, priority has been claimed by
Swaim in a book that appeared at Philadelphia in 1829 under the title of
_The Mural Diagraph_, and in a communication inserted in the _Comptes
Rendus_ of the Academic des Sciences for Nov. 27, 1865.
[Illustration: FIG. 3.]
In 1828, likewise, Victor Triboaillet de Saint Amand proposed to
construct a telegraph line between Paris and Brussels. This line was to
be a subterranean one, the wire being covered with gum shellac, then
with silk, and finally with resin, and being last of all placed in glass
tubes. A strong battery was to act at a distance upon an electroscope,
and the dispatches were to be transmitted by the aid of a conventional
vocabulary based upon the number of the electroscope's motions.
Finally, in 1844, Henry Highton took out a patent in England for a
telegraph working through electricity of high tension, with the use of
a single line wire. A paper unrolled regularly between two points, and
each discharge made a small hole in it, But this hole was near one
or the other of the points according as the line was positively or
negatively charged. The combination of the holes thus traced upon two
parallel lines permitted of the formation of an alphabet. This telegraph
was tried successfully over a line ten miles long, on the London and
Northwestern Railway.
[Illustration: FIG. 4.]
We have followed electrostatic telegraphs up to an epoch at which
telegraphy had already entered upon a more practical road, and it now
remains for us to retrace our steps toward those apparatus that are
based upon the use of the voltaic current.
* * * * *
Prof. Dolbear observes that if a galvanometer is placed between the
terminals of a circuit of homogeneous iron wire and heat is applied, no
electric effect will be observed; but if the structure of the wire
is altered by alternate bending or twisting into a helix, then the
galvanometer will indicate a current. The professor employs a helix
connected with a battery, and surrounding a portion of the wire in
circuit with the galvanometer. The current in the helix magnetizes the
circuit wire inclosed, and the galvanometer exhibits the presence of
electricity. The experiment helps to prove that magnetism is connected
with some molecular change of the magnetized metal.
* * * * *