1819.] by Means of Windmill Sails. 357 



any considerable burden, to perform a moderate voyage even, 

 would leave but little space for freightage ! However extraordi- 

 nary this may appear, it is nevertheless indisputable ; to prove 

 which, I will instance a boat of 80 tons (said to be the most 

 perfect of its kind) which navigates the Clyde, propelled by an 

 engine of 14 horse power, and which consumes \± cwt. of coals 

 per hour ! The quantity, therefore, which would necessarily be 

 required for a ship to perform, as stated, a moderate voyage 

 only, is almost incalculable, particularly as the increase of velo- 

 city is not in proportion to the increase of the power of the 

 steam-engine ; for the resistance, to which a boat is subject, 

 increases not in an arithmetical proportion, but in proportion to 

 the squares of velocity ; in other words, to make the same vessel 

 move with 10 times a given velocity, it requires 100 times the 

 power.* 



Again, it is known how ungovernable a steam-vessel is, when 

 any part of the machinery chances to be deranged ; when, therefore, 

 its complication is considered, and the vessel's dependence upon 

 that power alone, the danger of navigating oceans like the 

 Atlantic or Pacific, becomes multiplied in a ratio, equal to the 

 distances of the ports of departure or destination. In fact, 

 numberless causes may occur to retard a vessel's progress so 

 propelled ; so that steam, in this instance, can derive but little 

 value from the circumstance of its being independent of the 

 operations of winds and tides. 



Indeed, the propulsion of ships of any considerable magnitude, 

 by that power, to answer a profitable purpose, seems no longer 

 tenable, even upon paper ; and, however theoretically ingenious, 

 we can only lament that it is not more practically useful. 



The object of the present address is to suggest the employ- 

 ment of windmill sails as substitutes for steam, m giving motion 

 to the paddles : by this means a power, at least equal to that of 

 steam, may be obtained ; and as those sails are at all times 

 capable of being turned to the wind, to receive its impulse, the 

 advantages of sailing against wind and tide will be retained, the 

 cost of machinery very considerably lessened, the expenditure 

 and inconveniences of fuel saved, and the danger, in comparison, 

 with steam, rendered as nought. 



Of the practicability of the measure, I conceive it only neces- 

 sary for a person (however ignorant he maybe of the mechanical 

 power of the lever) to witness the sails of a windmill in motion 

 to be convinced ; but an accession of force would be obtained 

 by the employment of this power to the purposes of navigation,, 

 which, if I am not mistaken, is new in physics — I mean the ex^ 

 cess of velocity which would be acquired by progression, thus, 

 constituting power multiplied by power ; for no sooner would the 

 lis inertia of the body to be propelled be overcome, than the; 



* Sec Recs'a Enej. Art. Steam-boat. 



