428 THE CENTURY, 



valve at A, having above a platform G, on which is a 

 loaded truck F, attached by a cord a, at one end pass 

 ing over a pulley, and the drum wheel D, to the piston 

 B ; and a second cord at the other end passing over a 

 pulley at a , attached in like manner to the other piston 

 C. Steam having been admitted to B, on its condensa 

 tion the piston descending draws along with it the 

 weighted truck F, while the piston 0, ascends, drawing 

 in air at E. 



We thus attain the strict letter of the conditions set 

 down, \hefall and the advance being equal. 



28. 



A Bridge portable in 1 a Cart with 

 six horfes, which in a few hours 

 time may be placed over a River 

 half a mile broad, whereon with 

 much expedition may 2 be tranfport- 

 ed Horfe, Foot and Cannon. 



1 upon a. MS. and P. 2 there may be. 



\_A portable Bridge. ] The great painter, Leonardo 

 da Vinci, born in 1452, and who died at 67 years of 

 age in 1520, was a man of singularly inventive talent. 

 Among his other projects, he declares : &quot; I have the 

 means of constructing light bridges, easy of carriage, 

 and equally adapted to pursue or escape an enemy, 

 secure from fire ; and as easy to remove as to replace ; 

 and also the means of destroying those of the enemy.&quot; 

 See an interesting Memoir of him by J. W. Brown. 

 12mo. 1828. 



Bourne s 94th Device promises, &quot;How you may 

 make a bridge upon a sudden, that a whole army of 

 men and their carriages may pass over any river or 



