This apparatus, which is shown by Figs. 1, 2, and 3, consists of a
wooden case, A, of oblong shape, closed by a lid fixed by hinges to the
top or one side of the case. The lid is actually a frame for holding a
piece of wire gauze, L L, through which the sound waves from the voice
can pass. In the case a flat shallow box, E F (or several boxes), is
placed, on the lid of which the carbon microphone, D C (Figs. 1 and 3),
which is of the ordinary construction, is placed. The box is of thin
wood, coated inside with petroleum lamp black, for the purpose of
increasing the resonance. It is secured in two lateral slides, fixed to
the case. The bottom of the box is pierced with two openings, resembling
those in a violin (Fig. 2). Lengthwise across the bottom are stretched a
series of brass spiral springs, G G G, which are tuned to a chromatic
scale. On the bottom of the case a similar series of springs, not shown,
are secured. The apparatus is provided with an induction coil, J, which
is connected to the microphone, battery, and telephone receiver (which
may be of any known description) in the usual manner.
[Illustration: Fig. 1.]
The inventors claim that the use of the vibrating springs give to the
transmitter an increased power over those at present in use. They state
that the instrument has given very satisfactory results between Ostende
and Arlon, a distance of 314 kilometers (about 200 miles). It does not
appear, however, that microphones of the ordinary Gower-Bell type, for
example, were tried in competition with the new invention, and in the
absence of such tests the mere fact that very satisfactory results were
obtained over a length of 200 miles proves very little. With reference
to a statement that whistling could be very clearly heard, we may remark
that experience has many times proved that the most indifferent form of
transmitter will almost always respond well and even powerfully to such
forms of vibration.--_Electrical Review_.
[Illustration: Fig. 2.]
[Illustration: Fig. 3.]
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