HUNT’S PROPELLER. 
55 
Fig. 48. 
the same apparatus, a is a vertical axis, on the upper end of which is keyed 
a bevel wheel e, which is moved by another bevel wheel (not shown) worked 
by the engines. The axis d works through a hollow gun-metal axis which is 
attached to, or rather forms part of, a case or box ff. This case is supported 
by a bearing /, in which it can turn freely; j is a blade extending from the 
hollow axis and box, and constitutes the rudder. The box contains another pair 
of bevel wheels g h, communicating motion from the vertical axis d to the pro 
peller a «, which consists of four wrought iron vanes which have a uniform tortion 
so as to form sections of a helix. It will now be readily understood that if the 
hollow axis be by any means prevented from revolving, the motion of the ¿ngines 
will be communicated from the engine shaft to the propeller through the bevel 
wheels. To steer the vessel there is a worm wheel (not shown) which takes into 
a sector k affixed to the hollow axis, so that by communicating motion to the 
worm, the whole apparatus is turned round, and consequently the rudder also 
(in the same manner as the vanes of a windmill are turned to the wind), without 
interfering with the action of the wheels. The axis d has a hole drilled through