396 W. A. Norton on Ericsson’s Caloric Engine. 
piston a diameter of 11 feet 5 inches. The ratio of the’ areas 
of these pistons, and therefore also the ratio of the volumes 
of the two cylinders is as 3 to 2. The working piston is six feet 
deep, and concave underneath to fit the cylinder-bottom. The 
top and bottom, as well as the sides, are of iron, but the space 
between them is filled with gypsum and charcoal, non-conduc- 
tors of heat. The packing of the piston is at the top. The 
working cylinder is of necessity prolonged six feet below the 
position of the top of the piston when at its lowest point, thus 
forming a large vessel, called the heater, or heating chamber, 
into which the air passes from the receiver. By this arrange- 
guage. ‘The communications between the receiver and the heat- 
er, and between the heater and the external air are closed by tw 
puppet-valves. These valves are shown in the diagram at g au 
h. The one I will call the upper, and the other the lower valve. 
Tl le thermometers at J, », m, serve to indicate the temperature of 
he. it When the working piston reaches 
point, that is, is nearly in contact with the cylinder 
erneath forced Up. 
: 48 of the stroke this valve is closed, and the heated 
air acts expansively to the end of the stroke. ‘The lower valve 
is now opened, and the same body of air escapes through it into 
| 
| 
