[ 426 ] • 



JL-XIir. Descrlplion of certain Inventions for the Improve- 

 ment of Naval ylrckitecture^ for increasing the Comforts 

 of Mariners, a;idfor faalilating Nnval Enterprises. J5y 

 Messrs. R, TuEVirHicK' o«£2 K. Dickinson. 



[Continued from p. 391.] 



An our last Number \vc gave the advantages proposed to be 

 ilerived from Messrs. Trevilhick ;u;d Dickinson's improved 

 svstem of towing ships, 8cc., by employing for this pur- 

 pose the power of a steam engine, but without attempting 

 to specify how ihcv propose to apj>ly thi.^f power. They men- 

 tion two method:-, both of them ingenious. — One of them 

 is by employina; a levolving wheel furnished with leave? 

 to lay ho'iil of the water, .ind worked by the steam engine. 

 At first sight there appears no novtity in this idea, l)ut llie 

 way in which they dispose of their wheel is perfectly difle- 

 rent frotn any thing we have hitherto met with. It is placed 

 ill an air-tight receptacle open only at the liotlom, in which 

 the height that the water is permitted to rise (or, in other 

 words, the depth of the dip of the wheel) is perfectly under 

 the command of an air pump worked by the engine. Tlicir 

 seconcrmcihod, and which we would prefer, is as follows: 

 A wheel, or a sufficient portion of a wheel, \o which an 

 nrm of considerable length is attached, receives an alter- 

 nating motion by being worked into by a rack on the pis- 

 ton rod of the engine. The arm just mentioned is em- 

 ployed to give nnilion to a valve or valves included in a 

 hollow trunk or prism attached to, or actually contained 

 in, the vessel, placed longitudinally, and made of a size 

 suited to the cflect that is desired. The power of this ap- 

 plication will be easily conceived froiTi the following con- 

 sideratiims : — When the stroke of an oar, or any similar 

 implement, is made against water for the purpose of ob- 

 taining a reaction as nearly as may be similar to tliat of the 

 resistance of an immoveable body, part of the force is lost 

 in producing a lateral motion in the water, which escapes 

 sideways, and the blade of the oar is far from being sta- 

 tionary. If the oar were to pass in a channel or groove to 

 which it fitted, and of such a length as to present a long 

 prism of v.ater before the oar which could no otherwise 

 move than by passing out of the channel, it is demonstra- 

 ble that the mass of the said prism of water may be assumed 

 of such a magnitude as to render the actual motion of the 

 oar by a given force, and during a given time, less than 

 any assignable quantity. Now this is precisely the princi- 

 ple 



