urer, from a physical
standpoint, than that of the press or coining mill. Through very
simple considerations, we thus reach the principle which was
enunciated, we believe, by the illustrious Stokes, that our idea of
solid and liquid bodies is a necessary consequence of the intensity of
gravity upon the earth. Upon a larger or smaller planet, a certain
number of solid bodies would pass to a liquid state, or inversely. Let
us return to the cyclostat. In default of gravity, centrifugal force
gives us a means of realizing certain conditions that we would find in
the laboratory of our magician. The cyclostat permits us to observe
what is going on in that laboratory without submitting ourselves to
forces that might cause us great annoyance. We have hitherto been
content to put poor frogs therein and study upon them the effect of
the central anaemia and peripheral congestion produced on their
organism by the unrestrained motion of the liquids carried along by
centrifugal force. The results, it seems, have proved very
curious.--_La Nature_.

* * * * *

MERCURY WEIGHING MACHINE.

We illustrate herewith a novel type of weighing machine. Hitherto the
weighing machines in common use have either been designed with some
kind of steelyard apparatus, upon which weights could be moved to
different distances from a fixed fulcrum, or springs have been so
applied as to be compressed to different degrees by different weights
put upon the scale pan, or table, of the machine. In other instances
more complicated mechanism is used, and various movable counterpoises
are usually required in order to balance the moving parts of the
machine.

[Illustration]

The type of machine which we now illustrate has been recently brought
out by Mr. G.E. Rutter, and the system has given very satisfactory
results with platform weighing machines. The engraving illustrates a
form of balance which may be applied to strength testing machines, or
for any work where an apparatus of the type of a Salter's balance
would be of use. It is simple in construction, and consists of a tube
A closed at the bottom and forming a reservoir for mercury. The body
which it is required to weigh is hung upon the hook B carried by the
crossbar C, which is connected by rigid rods to the upper part of the
tube, and by means of the internal rods D is attached to the cross
head E, which works freely inside the tube A. The top part of the tube