The variations in the resistance of the circuit, due to variations in the
temperature, and the variations in the height of the column of mercury, due
to atmospheric variations, etc., are, according to the inventor, of no
importance.

It would evidently be possible, on the same principle, to construct an
apparatus for registering the indications of a thermometer at a distance.

Such is the principle of Mr. Gime's apparatus. We do not believe that they
are entirely closed to criticism. What, in fact, are the conditions
essential for their proper working? Evidently: (1) the constancy of the
battery used; (2) a rigorously accurate adjustment. This latter condition,
is easily realized; but the same is not the case with the former. Of what
elements shall this constant battery be formed?

Mr. Gime recommends the use of the Latimer-Clark elements. Every one knows
that the Latimer-Clark element is now the best standard of electromotive
force; but let us not forget that this is on condition of its being
employed in open circuit. Now, it is not a question here of an open
circuit, nor even of infinitely weak currents, since in the line we have a
solenoid whose core must set in motion a whole system of connected pieces.
We do not see any possibility of employing Latimer-Clark elements; on the
contrary, it seems to us indispensable to select piles of large discharge,
since the solenoid, S, will attract nothing at all unless a notable
quantity of energy is expended in it.

Is there a pile of this kind so constant as not to render a rigorously
accurate adjustment illusory? Therein lies the entire question, and for our
part we hesitate to pronounce ourselves in the negative.--_La Lumiere