nular form and pivoted so that it becomes a horizontal
fly-wheel. Obstructing projections on the inside periphery of the
annular tank assist the water to carry the latter along with it in its
circular motion.

For small steam motors, particularly for agricultural and domestic
purposes, the turbine principle is destined to render services of the
utmost importance. The prospect of its extremely economical
construction depends largely upon the fact that, with the exception of
two or three very small bearings carrying narrow shafts, it contains
no parts demanding the same fine finish as does the cylinder of a
reciprocating engine. It solves in a very simple manner the much-vexed
problem of the rotary engine, upon which so much ingenuity has been
fruitlessly exercised. The steam-turbine also has shown that, for
taking advantage of the generation and the expansive power of steam,
there is no absolute necessity for including a steam-tight chamber
with moving parts in the machine.

For very small motors suitable for working fans and working other
household appliances, the use of a jet of steam, applied directly to
drive a small annular fly-wheel filled with mercury--without the
intervention of any turbine--will no doubt prove handy. But in the
economy of the future such appliances will take the place of
electrical machinery only in exceptional situations.

One promising use of the turbine or steam-jet--used to propel a
fly-wheel filled with liquid as described--has for its object the
supply of the electric light in country houses. In this case the
fly-wheel is fitted, on its lower side, to act as the armature of a
dynamo, and the magnets are placed horizontally around it.

The full effective power from a jet of steam is not communicated to a
dynamo for electric lighting or other purposes unless there be a
definite ratio between the speeds of the turbine and of the armature
respectively. This may be conveniently provided for, with more
precision and in a less elaborate way than that which has just been
described, if the steam jet be made to drive a vertically pendant
turbine, the lower extremity of which, carrying very small horizontal
paddles, must be inserted into the centre of a circular tank.

The principle upon which the reduction of speed necessary for the
dynamo is then effected depends upon the fact that in a whirlpool the
liquid near the centre runs nearly as fast as that on the outer
periphery, and therefore--the