56 Ruthven’s Hydraulic Propellor. 
the nozzles against the outside water. But this is not the 
case; the propelling force is similar to the recoil produced 
by firing a gun. 
The advantages which are claimed for this propeller will 
be seen on reading the following :— 
1. No loss of power from slip, as in the paddle-wheel or 
screw, hence greater power is obtained from the same 
quantity of fuel. 
2. The power of the engines is uniform and continuous, 
producing smooth motion; the vessel is, therefore, free 
from vibration, and the great wear and tear caused by it. 
3. No reaction on the engines from pitching or rolling in 
a heavy sea, the propelling power remains efficient as in a 
calm ; thus obviating the risk of breaking shafts, paddles, 
or other parts of the machinery, of so frequent occurrence 
in other steam ships; and, on a long voyage, this absence 
of reaction would practically give an increase of speed, or 
economy of fuel. 
4. The vessel is independent of her rudder, and can be 
turned on her own centre by the propeller alone, without 
the helm and without steerage way. 
5. Can be backed astern or turned instantaneously under 
the complete control of the commander, officer of the watch, 
or look-out man on deck, no communication being neces- 
sary with the engines, as for this purpose these never 
require to be slowed, reversed or stopped. 
6. The propelling power being situated within the vessel, 
the risks to paddles or screws from shot, fouling, or other 
accidents are avoided. 
7. This propeller will work effectually whateverthedraught . 
of water may be. If the vessel float, she must be pro- 
pelled and would ascend rivers against. any current of less 
than the usual speed of the vessel, and under circumstances 
when either paddle or screw would be useless. There not 
being any wash or swell created, all injury to the banks is 
avoided ; a great consideration on canals and streams with 
artificially formed banks. 
8. In the construction of the hull the lines of a perfect 
sailing ship can be maintained, these propellers in no way 
interfering with the efficiency of the vessel as such; and 
from the facility with which the propelling power can be 
at once shut off and resumed in any weather without heav- 
ing-to, shortening sail, or lessening the speed of the ship, 
every advantage can be taken of favourable wind of how- 
