Regulating the Movements of Steam-Vessels. 165 
the greatest facility and certainty that could be wished for. 
These bevel wheels, spur-pinions, and racks, must be so pro- 
portioned to one another, as that two complete turns of the han- 
dle 1 raises the eccentric rod from the lowest to the highest po-» 
sition. One turn of the handle raises or lowers the eccentric 
rods into the stopping position, and one turn, either the one way 
or the other, as circumstances require it, sets the boat ahead or 
astern. There is a projecting piece 7, fixed upon the upright 
shaft, which catches into a notch, pressed by a spring, which 
supports the racks and eccentric rods, at any of the three posi- 
tions that may be required. 
As the said upright shaft makes two turns, and always stops 
at the same point, it is not suitable for the index. To remedy this, 
there is a small pinion 8, below the table, working into a wheel 
9, with four times the number of teeth, for carrying the index 
10. This wheel, making but half a revolution for two revolu- 
tions of the upright shaft, makes the index upon its arbour stand 
fore and aft when the engines are going, and thwart ships when 
the eccentric rods are set in the standing position. 
The index 11 is connected with the regulating valve 12 by 
rods and spanners, and turned by hand, as circumstances re- 
quire. 
The index 15 is connected with the injection-cock by rods 
and spanners, it being always shut before the engines are stop- 
ped, and opened when the engines are started. Each engine 
has separate gearing for the regulating valves and injection-cocks, 
and graduated circles on brass plates, to show, by inspection, the 
position in which they are standing. 
When the engin.es stand for some time, it is necessary to let 
the steam pass freely through them for two or three seconds, on 
purpose to heat them, and expel any air that may have got in- 
side. For this purpose, the long handle 14, standing by the side 
of the table, is fixed to a shaft 15, which goes across the front of 
both engines, and by four short spanners (or pallets) upon it, lifts 
all the valves of both engines, and allows the steam to pass freely 
through them by the air-pump valves. The engineer knows by 
the sound, when to replace the handle in the position shown in 
the sketch ; and having previously set the index for the head or 
stern motion in the direction wanted, and adjusted the steam re- 
l 2 
