394 W. A. Norton on Erricsson’s Caloric Engine. 
double, the two cylinders being placed one above the other... The 
lower one, which is the larger of the two, is called the working 
cylinder, and the other the supply cylinder. The working eyl- 
inder is entirely open at the top, and the supply cylinder at the 
bottom. The pistons which play in the two cylinders are con- 
nected by eight strong iron columns, and move up and down to- 
gether; the length of the stroke is therefore, of necessity, the 
same for each, viz: 6 feet. For the sake of distinction, the pis- 
ton in the working eylinder is called the working piston, and the 
piston in the supply cylinder the supply piston. Underneatl 
each working cylinder is a furnace, which heats the air in this 
cylinder beneath the piston, and by thus increasing its expansive 
force, furnishes the motive power of the engine. The expansive 
force of this heated air drives the working piston up, and with it 
the supply piston. During the ascent the air above the supply 
piston which is compressed before it passes through a communi 
cating pipe into the working cylinder, and receiving an accession 
of heat keeps up the ascensional force. When the pistons have 
reached their highest point, a valve is opened by the machine, 
which establishes a free communication between the compresse 
and heated air under the working piston and the external air; it 
flows out, and the two connected pistons descend by their own 
weight. It is to be observed, however, that the mechanical effect 
of this descending weight is but a compensation for the dimimu- 
tion of mechanical effect produced by the same weight in the as- 
cent, and that the weight of the pistons therefore forms no part 
of the real motive power of the engine. ~ more 
Confining our attention to the pair of double cylinders posited 
on either side of the main shaft, in the vacant space between the 
working and supply cylinders is placed a horizontal working 
beam, turning upon a shaft lying between the two double eylin- 
ders. One of the supply pistons is connected with one en 
of this working beam and the other with the other end; by 
means of links and connecting rods: and so, by the alternate ac- 
tion of the two working pistons, a reciprocating movement 1S 
communicated to the working beam. It will be seen therefore, 
that one double cylinder, with the necessary appurtenances, eof 
Stitutes a single acting engine, and that each contiguous Pe 
double cylinders, standing on either side of the main shaft, DY 
ds of a work- 
beam, form a double acting engine; that they accomp! 
same end as one double acting steam engine. ingly 
The shaft of the paddle wheels of the Eriesson is, according 
driven by two double acting engines; one before and the other 
abaft the shaft. Each of these engines has its separate working 
: The power is transferred from each of peed oe 
ms to the shaft, (which, it is to be observed, is copsie 
the connection of their pistons with the opposite en 
