depositing thin strips or wires of tough copper on to
sheets of insulating material for wrapping round the magnets and other
effective parts intended for dynamos. There is no fundamental reason
which forbids that when electro deposition is resorted to for the
recovery of a metal from its ore it should be straightway converted to
the shape and to the purpose for which it is ultimately intended. This
consideration has presented itself to the minds of some of the
manufacturers of aluminium, who make many articles intended for
household use electrolytically; and it must affect many other trades
which are concerned in the output and in the working-up of metals
readily susceptible of deposition--more particularly such as copper.

The familiar aneroid barometer furnishes a hint for another convenient
form of small steam-engine. In seeking to cheapen machinery of this
class it is of the utmost importance that the necessity for boring out
cylinders and for planing and other expensive work should be avoided.
In the aneroid barometer a shallow circular box is fitted with a
cover, which is corrugated in concentric circles, and the pressure of
the superincumbent air is caused to depress the centre of this cover
through the device of partially exhausting the box of air and thus
diminishing the internal resistance. To the slightly moving middle
part of the cover is affixed a lever which actuates, after some
intermediate action, the hand which moves on the dial to indicate, by
its record of variations in the weight of the atmosphere, what the
prospect of the weather may be.

In the aneroid form of the steam-engine the cylinder is immensely
widened and flattened, and the broad circular lid, with its spiral
corrugations, takes the place of the piston. The rod, which acts
virtually as a piston-rod, is hollow, and it works into a bearing
which permits the steam to escape when the extreme point of the stroke
has been reached into a separate condensing chamber kept cool with
water. The boiler itself, with corrugated top, may take the place of
the cylinder.

In some respects this little machine represents a retrograde movement,
even from Watt's original engine with its separate condenser; but its
extreme economy of first cost recommends it to poor producers. In the
near future no country homestead will be without its power
installation of one kind or another, and there is room for many types
of cheap motors.

A motor like the steam-turbi