On the Theory of a new species of Locomotive Vessel. 447 



stals. This, although an unnecessary complication, would 

 not be of very material consequence were the form to occur 

 onJy in a simple or isolated state ; but as it occurs far more 

 generally in combination with oblique rhombic prisms or 

 pyramids, the anomaly arises, that either the rhomboidal or 

 the rhombic form becomes unavoidably placed in an incorrect 

 position. The harmony, -so to say, existing amongst the in- 

 dividual forms of the same crystallographic group is thus de- 

 stroyed, without the substitution of any real advantage. The 

 employment, therefore, of right rhomboidal prisms is undoubt- 

 edly objectionable. 



LXI. On the Theory of a new species of Locomotive Vessel 

 that will diminish the ordinary resistance of the Water to one- 

 fortieth part of its retarding power in Vessels of the same 

 burthen. By George Walker, Esq., of Port Louis, 

 France. Communicated by Sir George Cayley, Bart. 

 [With a Plate.] 



GENERAL prejudice and even engineering incredulity, not 

 many years ago, denied the possibility of vessels being 

 propelled, unless we had the two elements of air and water to 

 act against each other ; and also affirmed, that turning the 

 wheels of railway vehicles by steam power could never give 

 them any useful impulse. 



Now the sea is kept in continued foam by the swift prows 

 of its tens of thousands of steam-boats ; and the land, of almost 

 every nation, is begirt with its iron roads in every possible 

 direction ; and monster-trains are every day conveying their 

 thousands at forty and fifty miles an hour. The incredulity 

 is forgotten ; and the parties so forgetting it are quite as ready 

 to avail themselves of these wonderful and most useful prac- 

 tical advantages, as if they had never disbelieved in their pos- 

 sibility, or opposed their nascent progress. Such, however, 

 is the history of human invention : at every new step, first 

 discovered by science, and then attempted to be realized by 

 art, the same incredulity and the same opposition has to be 

 met ; but after so many practical lessons on the determined 

 march of scientific engineering in the present age, it behoves us 

 to examine, with competent eyes, and to be more cautious, be- 

 fore we reject projects that startle our present ideas of what is 

 practicable, especially when they involve, if possible, an enor- 

 mous field of utility. 



The present announcement is of this class ; and its theore- 

 tical basis is all that is intended to be set forth in this com- 

 munication. 



