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.

Without any desire to seek an application for an experiment that is
simply curious, we yet believe that there is here a phenomenon of a
nature to be studied by physicists. Discoveries in telephony and
microphony have certainly opened up to science, as regards both theory
and practice, new horizons that still promise other surprises for the
future. But to return to the observatory: The success obtained by the
exhibition of the French Society of Physics shows that these reunions
respond to a genuine need--that of instructing in and popularizing
science. While warmly congratulating the organizers of these meetings,
we may express a wish that the good example set by the Society of
Physics may be followed by other societies. We are convinced in
advance that an equal success awaits them.--_La Nature._

* * * * *

ON THE ARRANGEMENT OF GROUND CONDUCTORS.

In telegraphy, as well as in the question of lightning rods, attention
has been but incidentally paid to the improvement of ground
conductors, and this point has not been the object of that careful
study that has been bestowed upon the establishment of aerial lines.
It is only recently that the interest created by lightning rods has
given rise to new forms of conductors differing from those formerly
used. The publications of the Prussian Academy of Sciences of from
1876 to 1880 contain some information of special importance in regard
to this. It is stated therein that the effect of ground conductors may
be notably increased by the division of the earth plates and the us