On the Various Modes of Propelling Vessels. 421 



ON THE VARIOUS MODES OF PROPELLING 

 VESSELS. 



BY PROFESSOR M C GAULEY. 



Some means of transport on water have been used from the 

 earliest times ; and as soon as the very rudest bark was in- 

 vented, efficient modes of propelling it were devised. The 

 principles applied to the propulsion of boats and ships have 

 never varied much. That of the oar, which undoubtedly was 

 the first contrivance employed, is also that of the paddle- 

 wheel and the screw propeller. There is good reason to 

 believe that the ancients used oars only for sculling ; and the 

 highest authorities on naval matters affirm that this is the best 

 mode of employing them. We use them almost exclusively 

 for rowing. 



The wind offered a very convenient source of power, and, 

 accordingly, navigators soon availed themselves of it. But the 

 ancients placed more confidence in oars for the purposes of 

 war ; and hence, for either aggression or defence, they used 

 biremes, triremes, quadriremes, etc., which have given anti- 

 quarians such trouble, and the nature of which is still involved 

 in great uncertainty. The employment of oared gallies con- 

 tinued until a comparatively recent period ; the Turks and 

 Venetians retained them, long after sailing vessels of a very 

 perfect form had been constructed, and we ourselves did not 

 relinquish them until the reign of Henry VII. 



Since my purpose is chiefly to speak of mechanical modes 

 of propulsion, the consideration of sails, as a means of obtain- 

 ing motion, is almost beside my purpose. The small cost at 

 which power is obtained from the wind will, however, probably 

 cause sailing vessels to continue always in use. The disuse of 

 them as ships-of-war seriously affects our position as the 

 masters of the sea. 



Oars, made to revolve in a plane parallel to the sides of a 

 vessel, afforded a paddle-wheel ; and hence, in very early times, 

 attempts were made to apply in that way the principle of the 

 oar to the mechanical propulsion of ships. Paddle-wheels, 

 similar to oars, were used by the Egyptians, the Romans, and 

 the Carthaginians. But, until steam became applicable as a 

 source of motion, no kind of mechanical propulsion could be 

 equal to that obtained by means of oars. Hence the invention 

 of the steam-engine, properly so called, and the practical 

 adoption of the paddle-wheel were nearly simultaneous. 



Paddle-wheels give rise to a great loss of power, on 

 account of the way in which they enter and leave the water, 



