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Page 29
Measuring apparatus were represented by a new and very elegant
arrangement of Sir William Thomson's reflecting galvanometers, due to
Mr. J. Carpentier. The mounting adopted by Mr. Carpentier permits of
an easy removal of the bobbins and of an instantaneous substitution
therefor. The galvanometric part, composed of the needles and mirror,
therefore remains entirely free, thus allowing of its being verified,
and making it convenient to attach the silken fiber. Mr. Carpentier
has, moreover, adopted for all the minor apparatus a transparent
celluloid scale which simplifies them, facilitates observations, and
renders the use of reflection almost industrial.
We shall complete our enumeration of the measuring apparatus by citing
Ducretet's non-oscillating galvanometer, Sir William Thomson's
amperemeters, voltameters, ohmmeters, and mhosmeters, constructed and
exhibited by Breguet, and a new aperiodic galvanoscope of Mr. Maiche.
Mr. Baudot exhibited the recent improvements that he has made in his
multiplex printing telegraph, and M. Boudet of Paris showed a new
system of telephone transmission by submarine cables.
[Illustration: FIG. 1.--DIAGRAM EXHIBITING THE ARRANGEMENT FOR
TELEPHONIC TRANSMISSIONS WITHOUT A RECEIVER.]
Finally, we shall conclude our enumeration by referring to the
curiosities. The house of Siemens exhibited a miniature electric
railway actuated by a new model of Reynier accumulators; M. Maiche
operated a system of musical telephonic auditions that differed only
in detail from those instituted by Mr. Ader at the exhibition of 1881;
and Mr. Hospitalier presented a new form of an experiment devised by
Mr. Giltay, consisting of a telephonic transmission of sounds without
the use of receivers. Mr. Giltay's experiment is nothing but Mr.
Dunand's speaking condenser without the condenser. A glance at Fig. 1
will show how things are arranged for the experiment. The transmitting
system comprises two distinct circuits, viz.: (1) one formed of a
pile, P, of 2 or 3 Leclanche elements, or of 1 or 2 small sized
accumulators, an Ader microphane transmitter, M, and the inducting
wire of a small induction coil, B; and (2) the other formed of the
induced wire of the coil, B, of a pile, P', of 10 or 12 Leclanche
elements, and of a line whose extremities terminate at R, in two
ordinary electro-medical handles. With this arrangement the experiment
performed is as follows: When any one speaks or sings in front of the
transmitter, T, while two persons, A and B, each having one hand
gloved, are holding the handles in the ungloved hand, it is only
necessary for A to place his gloved hand upon B's ear, or for the
latter to place his hand upon A's, or for each to place his hand on
the other's ear simultaneously, in order that A or B, or A and B
simultaneously, may hear a voice issuing from the glove. Under these
circumstances, Mr. Giltay's experiment is explained like Dunand's
speaking condenser--the hand of A and the ear of B here constituting
the armature of an elementary condenser in which the glove performs
the role of dielectric.
Upon repeating this experiment at the laboratory of the School of
Physics and Industrial Chemistry of Paris, it has been found that the
glove maybe replaced by a sheet of plain or paraffined paper. In this
case, when two persons are holding the handles, and have their ears
applied, one against the other, if a sheet of paper be interposed,
airs or words will be heard to proceed therefrom. Finally, it has been
found possible to entirely suppress the paper, or dielectric, and to
hear directly, by simply interposing the auditor or auditors in the
circuit. One of the most curious forms of the experiment is the one
shown in Fig. 2. Here a third person, C, hears the hands of A and B
speak when a circuit is formed by means of three persons, A, B, and C,
the two former, A and B, each holding one of the wires of the circuit
and applying his free hand to the ear of C. Although the experiment is
one that requires entire silence, and could not on that account be
performed at the laboratory, a sort of telephonic chain can be formed
in which five or six persons may hear at the same time. A, putting his
hand on the ear of B, the latter putting his to that of C, and so on
up to the last person, who closes the circuit by grasping one of the
handles, the other one being held by A.
[Illustration: EXPERIMENT ON TELEPHONIC TRANSMISSION WITHOUT
RECEIVING APPARATUS.]
It is difficult in the present state of science to explain very
clearly how these telephonic transmissions are effected without a
receiver. All that we can conclude from it so far is that the ear is
an instrument of incomparable delicacy and of exquisite sensitiveness,
since it perceives vibrations in which the energy developer,
particularly in the telephonic chain, is exceedingly feeble.
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