work
of an element of a round Bunsen
having a zinc of element, 20x30 cm.
16x20 cm.

Volts. 1.9 1.8
Resistance. 0.05 0.24
Work disposable in the
external circuit. 1.839 k. 0.344 k.

The work disposable in the external circuit is deduced from the
formula:

T = E squared/(4R x 9.81)

It will be seen that an element thus charged gives as much energy as
5.3 large Bunsen elements.

The battery is charged with 10 liters of solution, and is capable of
furnishing for 5 hours a current of 7 amperes with a difference of
potential of 9 volts at the pile terminals. The work, according to the
formula (EI)/g, equals 6.422 kilogram-meters; with a feebler
resistance in the external circuit it is capable of producing a
current of 19 amperes for an hour and an half. In this case the
resistance of the external circuit equals the interior resistance of
the pile. Upon immersing the electrodes in new liquid, and with no
resistance in the external circuit, the current may reach 100 amperes.
On renewing the liquids during the operation of the pile, a current of
7 amperes is kept up if about a liter of saturation per hour be
allowed to pass into the battery. For five hours, then, only 5 liters
are used instead of the 10 that are necessary when the liquid is not
renewed while the pile is in action.--_La Nature._

* * * * *

WOODWARD'S DIFFUSION MOTOR.

The energy produced by the phenomena of diffusion is exhibited in
lecture courses by placing a bell glass filled with hydrogen over a
porous vessel at whose base is fixed a glass tube that dips into
water. The hydrogen, in diffusing, enters the porous vessel, increases
the internal pressure, and a number of bubbles escapes from the tube.
On withdrawing the bell glass of hydrogen, the latter becomes diffused
externally, a lower pressure occurs in the porous vessel, and the
level of the water rises.

The arrangement devised by Mr. C.J. Woodward, and recently presented
to the Physical Society of London, is an adaptation of this experiment
to the production of an oscillating motion by alternations in the
internal and external diffusion of the hydrogen.

The apparatus, represented herewith, consists of a scale beam about
three feet in leng