inert--a defect which is apparent at first sight. It results from this
that as soon as we propose to obtain an electromotive force, however
slight it be, we must get it with machines of large dimensions. Now,
it is permissible to believe that under such circumstances (taking
into consideration the complication of mechanical means that the
construction of such apparatus necessitates, and the great friction
that occurs) it would be impossible to obtain practical rotary
velocities. Comparing his machine with Gramme's, Prof. Pfaundler
expresses the idea that between them there is the same analogy as
there is between a constant pressure and an expansion engine. With
cylinders of equal diameters the work performed by the former of these
is greater than that done by the second, but in the latter the
expansive force of the steam is better utilized. This comparison seems
to us to be more ingenious than exact. Would it not be coming nearer
to the truth if we were to suppose a case of a hydraulic motor whose
performance continued diminishing with the height of the fall, and
would it not be advantageous under such circumstances to utilize only
a portion of the fall for the purpose of increasing the motor's
performance?

This machine, however, as before stated, has never as yet been
constructed, so that experimental data relative to its mode of working
are wanting. It is especially interesting as regards its origin, which
dates back to an epoch at which researches on the dynamo electric
machine were at their heat. It is in its historical aspect that it is
proper to regard it, and it is from such a point of view that we have
deemed it well to say a few words about it in this place.--_La Lumiere
Electrique._

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