DR. HERZ'S TELEPHONIC SYSTEMS.

In an article by Count du Moncel, published in SCIENTIFIC AMERICAN
SUPPLEMENT, No 274, page 4364, the author, after describing Dr.
Herz's telephonic systems, deferred to another occasion the
description of a still newer system of the same inventor, because at
that time it had not been protected by patent. In the current number
of _La Lumiere Electrique_, Count Moncel returns to the subject to
explain the principles of these new apparatus of Dr. Herz, and says:

I will first recall the fact that Dr. Herz's first system was based
upon the ingenious use (then new) of derivations. The microphone
transmitter was placed on a derivation from the current going to the
earth, taken in on leaving the pile, and the different contacts of the
microphone were themselves connected directly and individually with
the different elements of the pile. The telephone receiver was located
at the other end of the line, and when this receiver was a condenser
its armatures were, as a consequence of this arrangement, continuously
and preventively polarized, thus making it capable of reproducing
conversation.

[Illustration: DR. HERZ'S TELEPHONIC SYSTEMS.]

This arrangement evidently presented its advantages; but it likewise
possessed its inconveniences, one of the most important of these being
the necessity of employing rather strong piles and consequently of
exposing the line to those effects of charge which react in so
troublesome a manner in electrical transmissions when they occur on
somewhat lengthy lines. Now the fact should be recalled that Dr.
Herz's principal object was the application of the telephone to long
lines, and he has been applying himself to this problem ever since. He
at first thought of employing reversed currents, as in telegraphy; but
how was such a result to be attained with systems based upon the use
of sonorously-vibrating transmitters? He might have been able to solve
the problem with the secondary currents of an induction bobbin, as
Messrs. Gray, Edison, and others had done; but then he would no longer
have been benefited by those amplifications which are furnished by the
variations of pressure-derivations in microphones, and this led him to
endeavor to increase the effects of the induced currents themselves by
prolonging their duration, or rather by combining them in such a way
that they should succeed each other, two by two, in the same
direction; and this is the way he solved t