hour of steam for each electrical horse power with a steam pressure of
90 lb. above the atmosphere.--_Engineering._

* * * * *




HARGREAVES' THERMO-MOTOR.


From the researches and investigations of Carnot, Joule, Rankine,
Clausius, and Sir William Thomson, the science of thermo-dynamics has
not only been brought into existence, but fully matured. We learn from
it that whereas in the steam engine, on account of the limited range of
temperature in the working cylinder and the rapid conduction of steam
during condensation, no combination of cylinders can materially affect
its present efficiency, internally fired engines, such as gas and
caloric engines--being, as it were, less fettered--can have their
already high efficiency increased by simply overcoming mechanical
difficulties. To this fact is no doubt due the recent remarkable
development of gas and caloric engines. The first caloric or hot air
engine was invented by Sir George Cayley in 1807, and in 1827 Dr. Robert
Stirling, a Scotch minister, took out his first patent for a hot air
engine, which was the foundation of many subsequent machines, and by the
invention of the regenerator he converted what was practically a
scientific toy into an efficient machine.

One of the most ardent workers in this field at the present time is Mr.
James Hargreaves, of Widnes, who, with a thorough theoretical knowledge