2 On a New Form of 



ascertained respecting their efficiency, and the reasons that 

 have led scientific men to devote their attention to the dis- 

 co very of some new and better method of propulsion. 



The paddle wheels act on the surface of the water where 

 there is least resistance, and are liable to great irregularity of 

 action in a rough sea. There is, in consequence, a con- 

 siderable slip, or loss of velocity. The oblique action of the 

 floats on the water also involves a loss of power. 



The indirect transmission of power from the piston to the 

 paddle wheels through a ponderous crank engine involves 

 an additional loss of power. 



The paddle wheels also act to great disadvantage when the 

 vessel is either too heavily, or too lightly freighted. 



It has been estimated in a recent article in the New 

 York Commercial Gazette that of the actual motive-power 

 of the Collins steamers, not more than one-half is available 

 in their speed. 



The screw also has many serious defects, and notwith- 

 standing the great efforts that have been made to remove 

 them it has hitherto proved inferior to the paddle wheels, 

 especially when great velocity is required, or when there is 

 great resistance to be overcome — as in head winds ; and it 

 has, therefore, been chiefly used as an auxiliary in full-rigged 

 ships and men-of-war. 



The screw has the advantage of working in deep water, 

 where there is increased resistance ; but its oblique action 

 on the water is its great source of weakness, and is one of 

 those difficulties which cannot by any possible means be 

 remedied. 



If we look to Nature as our guide, and take the feet of 

 swimming birds, and the fins of fishes, as our model, we shall 

 see that a perfect propeller should act wholly under water, 

 as the screw, but, unlike the screw, the blades, or floats, of 

 the propeller should act at right angles to the water. 



The problem to be solved, therefore, is to discover some 

 simple and effectual means of feathering the floats of a pro- 

 peller under water without loss of power, and of reversing 

 their action when backward motion is required. 



Here it will, perhaps, be impossible in every respect to 

 imitate the natural propellers of swimming birds and fishes, 

 and especially that power which they possess of lessening 

 the surface and resistance of their propellers in the act of 

 feathering them ; but let the attempt, at least, be made to 

 imitate this natural action as far as possible, and if it should 



