CONCLUSION. 
67 
CONCLUSION. 
The ultimate fate of these methods of propulsion is now beyond the influence 
either of praise or depreciation. Four vessels are already in operation, fitted 
under the patent of Mr. Smith, and the ‘ Great Britain,’ now building at Bristol, 
is to be propelled with the screw driven by engines of 1000 horses’ power. A 
vessel of 1500 tons is also just completed at Londonderry, which is to be pro 
pelled in the same way. The British Government are fitting the Rattler, which 
is of 800 tons burden, and has engines of 200 horses’ power, to prove the 
power of the screw by competing with the Polyphemus, which is of the like power 
and tonnage ; and the French Government are fitting three vessels to be impelled 
by the same agency. Messrs. Rennie and others are also about carrying out their 
plans on a large scale. The rapid strides which the system has made in the 
space of two years, before which it was almost universally unpopular, are the best 
evidence of its importance ; and there can be no doubt that if the machinery for 
communicating motion from the engine to the screw can be rendered simple, 
and durable, this method of propelling will become useful as an auxiliary power, 
and in certain classes of war steamers, even if it should not be found equal to 
paddle wheels under all circumstances.