Propeller for Steam Ships. 3 



be found that there is necessarily some loss of power in 

 feathering the floats, under the most favourable conditions, 

 this will at least admit of beiug greatly diminished by 

 lengthening the stroke, and thus diminishing the frequency 

 of the feathering. A perfect propeller should also admit of 

 being connected directly to the piston-rod of the steam 

 cylinder, so as to avoid the loss of power necessarily resulting 

 from a heavy crank engine. 



This simple arrangement, however, would necessarily 

 depend on a much greater speed of piston than that already 

 attained. 



A perfect propeller should also, when in action, have very 

 little slip in the water, and when not in use it should either 

 be capable of being readily-lifted out of the water, or it 

 should offer no impediment to the motion of the ship under 

 canvas. Such are the necessary conditions, as it appears to 

 me, that we are to look for in any form of propeller that is 

 likely to offer superior advantages to the paddle wheels and 

 screw. 



These conditions, I think, will be readily admitted to be 

 theoretically essential, although it may be alleged that the 

 inventive genius of scientific men has already been taxed to 

 the utmost to discover such a form of propeller without 

 success. 



But are we, on this account, to despair of all further im- 

 provement in our modes of propulsion? If it is true that 

 one-half, or a larger per centage, of the steam power in 

 marine engines is lost, or unavailable, in its application to 

 the paddle wheels, and that the screw for purposes of speed 

 is in no respect superior to the paddle wheels, is it at all 

 likely, with these means of propulsion, that we shall ever 

 obtain a velocity commensurate with the requirements of 

 modern civilization? 



Can we allow ourselves to believe that there is the same 

 lavish waste of power in the mechanism which Nature has 

 provided for the rapid movement of aquatic birds and fishes 

 in their native element ? 



Past experience would seem to show that the larger the 

 vessel the less is the proportionate resistance with the same 

 lines and proportion of beam, and the greater the velocity 

 with the same proportion of propelling power. 



Unless, therefore, we are prepared to maintain that the 

 propelling power in fishes is much greater, in proportion to 

 their size, than is required in steam ships to obtain the same 



B 2 



