200 
St€<mi Engine. 
rack perpendicular ; the two radius bars on which 
the brasses are fixed that support the shaft ; by this con- 
trivance the wheel C easily moves from one side to the 
other of the rack F. 
Fig. 2. is a view of the rack on a larger scale, where C 
represents the wheel and D the shaft ; E E, a sliding bar, 
on which is fixed the small roller o, serving as a connect- 
ing link to keep the wheel C always in gear ; for, when the 
wheel is in gear on the opposite side of the rack, the rol- 
ler 0 is on the other side of the plate aa ; but it will per- 
haps be more clearly understood by the plan, Fig. 3^ 
where the letters represent the same movement as in the 
elevation, Fig. 2 : This description may be easily under- 
stood by those who already possess a little knowledge of a 
steam-engine. 
Description of a Steam Engine on the Principle of Sava- 
ry^ operating by a separate Condenser ; with other es- 
sential Improvements. By Mr. JohnNancarrow^. 
Plate III. Fig. 3. A. The receiver, which may be 
made either of wood or iron. 
BBBB. Wooden or cast-iron pipes for conveying the 
ivater to the receiver, and from thence to the penstock, 
C. The penstock or cistern. 
D. The water-wheel. 
E. The boiler, which may be either iron or copper. 
F. The hot-well for supplying the boiler with water, 
GG. Two cisterns under the level of the water, in, 
wliich the small bores BB, and the condenser are con- 
tained. 
HHH. The surface of the water with which the steam 
engine and water v/heel are supplied, 
* From a learned paper on Mills, in the American Transac- 
tions, IV. page 355. I have not been able to extract the theoreti- 
cal parts of the paper, because the plates and referenced are too 
imperfect. 
