Steam Pcmer in maintaining a Ferry. (iB 



force a vessel up a rapid stream by steam-paddles, and by 

 tracking. But the cases are, to a certain extent, the same. A 

 steam-tug, by herself, will acquire a momentum proportionate to 

 her qualities, and this momentum, applied to a rope towing ano- 

 ther vessel, will have the same superior efficacy with that above 

 stated, to what her power would have, were it embarked on board 

 of that vessel, — at least, not much less in any case, — in this 

 possibly a great deal more ; — and for the following reasons. 1. 

 A steam-tug, not being thrown out to receive a cargo, having 

 her paddles, as we have just seen, of the best form, and work- 

 ing them in the best way, may be expected to be a cleverer ves- 

 sel than one in which these points are subordinate to other and 

 contradictory qualities ; — she will thus be well fitted to form the 

 entrance, as it were, of the whole load to be moved, the sharp 

 end of the wedge to be employed in cleaving the waters. As 

 she must have substance also as well as power (bone as well as 

 blood) to fit her for a draught, the weight of her engine, which, 

 in ordinary cases, is only necessary incumbrance, will be posi- 

 tively beneficial to her ; — she will even probably require more 

 weight, which maybe judiciously disposed as ballast; and a 

 counterpoise being thus provided against the top-weight of her 

 engine, its several parts may be made stronger, and in some re- 

 spects even disposed more beneficially than in ordinary boats. 

 Lastly, she will deliver her power in the same straight line with 

 the direction in which the passage-vessel is to be impelled, where- 

 as the power in tracking acts obliquely. 2. The passage-ves- 

 sel will be absolutely smaller than a steam-boat of the same ca- 

 pacity, because the room occupied by the machinery will be 

 saved ; she will draw less water, as will presently be shewn, 

 than would be possible were she constructed to carry an engine ; 

 she will be built expressly to tow easily ; will ply in the smooth 

 water of her tug, which will cut the waves before her, and in 

 some degree prevent that accumulation of water under her 

 bows, which, increasing in ordinary cases as the square of the 

 velocity, is the greatest obstacle to easy and rapid sailing ; and 

 the power applied to her will, if properly led, tend to lift her ; 

 and, at all events, will act in one forward direction, — whereas a 

 rotatory impulse on l)oard of her would act in a circle, only one 

 APRIL — JUNE 1828. E ... 



