428 On the Various Modes of Propelling Vessels. 



mentalists rendered more serious than they naturally are. But 

 it still remains a question whether or not these difficulties may 

 be so far overcome that any contrivance of the kind can com- 

 pete, not only in efficiency, but — which is of, at least, equal 

 importance — in economy, with those already in use. 



Toogood, in 1661, and after him Allen, in 1730, proposed 

 to propel a vessel by means of a jet of water. Bernouilli, 

 Linaker, Ruthven, and many others, at different periods, fol- 

 lowed in the same path. With all such apparatus there must 

 be a loss of power, on account of the necessary changes in the 

 direction in which the fluid moves, and the great friction 

 arising from the large amount of rubbing surface. The fric- 

 tion of fluids against solids is so great, that the advantage 

 derived from a long sharp bow may be more than counter- 

 balanced by the increased length of the vessel. The friction 

 was enormously increased in the earlier contrivances by the 

 extreme narrowness of the waterways. This led to another 

 evil, — the smallness of the issuing current. The reaction of 

 the water against which this current impinges can be great, 

 and therefore a sufficient amount of resistance can be obtained, 

 only when the issuing stream is considerable. 



The principle of all such contrivances must be the same ; 

 the only difference consists in the mode of applying it. This 

 has been extremely varied. In some instances pumps have 

 been used ; in others, a horizontal water wheel, or turbine, 

 inclosed in a case, the water being drawn in generally at the 

 bow or the bottom of the vessel, and emitted at the stern or 

 the sides. In no department of practical science has the same 

 thing been invented over and over again so often as in this. 



Some interesting experiments are being made in America 

 with a vessel, at each side of which the fluid is made to issue 

 from pipes that are near the water-line, and are capable of 

 being turned either towards the stern or the bow, so as to 

 impel the vessel ahead or astern ; or, if those at opposite sides 

 are turned in opposite directions, so as to turn it round. 



Still more important experiments are being made in this 

 country with the " Water witch. " This vessel is fitted with a 

 turbine wheel, fourten and a half feet in diameter, working in a 

 chamber which, ordinarily, has no connection with the rest of 

 the vessel. The water enters from the bottom of the vessel, 

 through gratings, and issues by means of two pipes, run- 

 ning the whole length of each side of the vessel, and so 

 arranged that the fluid may escape from both orifices at the 

 stern, or both at the bow, or from one at the bow and another 

 at the stern, so as to turn the vesselon her centre. The issue of 

 the water is regulated by sluices, which are under the control 

 of an officer on deck, and can be worked without altering or 



