attached to its neck, and containing a liquid which served as the
inner armature. The author's attention had been called to the fact
that this phenomenon had been observed ten years ago by M. Gori.

His researches, just made public, leave no doubt of the accuracy of M.
Duter's view, that the glass of the jar really expands. According to
the theory of elasticity, the effect of an internal pressure in a
hollow sphere is in the inverse ratio of its thickness. M. Duter,
therefore, had three flasks made of the same volume, but of
thicknesses of 4 mm., 0.8 mm., and 0.5 mm. respectively. They were
filled with water and enveloped by tin foil. Each carried a capillary
thermometer tube, in which the variations of the height of liquid
served to measure the changes in volume due to electrification. He
found that these changes were imperceptible in the thick glass, very
marked in the flask of mean thickness, and rose to 30 mm. in the
thinnest. The variations in volume were very nearly in inverse ratio
of the square roots of the thicknesses.

* * * * *

A NEW ORE CRUSHER.

The accompanying engravings represent an improved ore crusher, which
is said to be very effective and economical in the use of power.

[Illustration: Fig. 1.--BROWN'S ORE CRUSHER.]

[Illustration: Fig. 2.--HORIZONTAL SECTION.]

A short vertical cast iron cylinder, A, having in one side a discharge
opening, H, contains all of the movable parts.

The upper portion of the cylinder is lined with chilled iron plates,
L, and an inclined chute, X, leads to the discharge opening, H.

A rigid shaft, B, carries the circular crusher, C, and moves in a ball
and socket joint at the upper end, and extends eccentrically through
the boss of a bevel wheel, G, at its lower end, and rests on a step
supported by a lever that may be adjusted by the screw, R. The wheel,
G, is driven by the pinion, P, on whose shaft there are a pulley and a
fly-wheel.

The double gyratory motion of the crusher, C, causes it to approach
all portions of the lining, L, crushing whatever lies between.

It is said that this machine is capable of crushing 10 tons of the
hardest ore per hour. Its weight is 6,500 lbs.--_Musee de
l'Industrie._

* * * * *

RECENT AMERICAN PATENTS.

Enos Richmond, of Troy, N. Y., has invented a steak tenderer, having
a plunger studded with chisel-pointed rods, and arranged in a case in