and on Miscellaneous lucent ions at the Biihninyhant Show. 283 
portion of the cylinder, while the lower portion of the 'power- 
cylinder is kept hot by the action of the fire below the heater F. 
The heating and also the cooling of the air are instantaneously 
■effected by its alternate presentation to the surfaces of the heater 
and cooler, in a thin annular sheet, such being found by expe- 
rience to be the only correct method of rapidly and thoroughly 
■effecting changes of temperature in air. 
Fig. 9. — Vertical Section of Messrs. Hayward Tyler and Co.'s 
Caloric Engine. 
This is accomplished as follows : — The compression-piston C 
extends downwards to the base of the engine, and is a trifle 
smaller than the interior of the cooler E, thus leaving a thin 
space on all sides for the air to pass downward and become 
thoroughly cooled on its way to the bottom, and through which 
space it flows on its way back to the heater. The power-piston 
D likewise extends downwards into the heater F, which in shape 
resembles the bottom of a champagne-bottle ; that is, rising in 
the centre, and presenting to the action of the fire a narrow 
