322 Review of Renwick 



To retain the valve in its position, the lever L, M, fig. 1, is fas- 

 tened to a bar of iron, N, O, (supported by the uprights, N, P, and 

 O, R, of the same material) by a chain, which is attached to N, O, 

 at one extremity, and which passing round the lever, returns through 

 an opening in N, O, to the top of the bar, where it is secured by a 

 padlock. In the drawing the area of the valve, I, K, is 4^ square 

 inches ; this, at 150 lbs. to the square inch, requires a weight of 675 

 lbs. to press it down. The short arm of the lever is 1^^ inch, the 

 long arm 30 inches, the weight, T, is then about 33 lbs. 



To raise the valve sufficiently above its seat, requires in the case 

 figured, stanchions of 12.4 inches high. The whole apparatus thus 

 occupies less than three feet in length, and eighteen inches in height. 

 The dotted lines represent the position of the valve when, after the 

 fusion of the plate, it may have been closed. 



Art. XVI. — -Treatise on the Steam Engine; by James Renwick, 

 LL. D. Professor of Natural Experimental Philosophy and Chem- 

 istry, in Columbia College, New York. New York : G. St C. &; 

 H. Carvill: 1830. pp. 328. 



The Steam Engine has become at the present day an object of 

 intense interest. The magnitude and variety of its performances 

 awaken the highest admiration, while its resistless energies, triumph- 

 ing as they sometimes do over the ingenuity of man that controls all 

 things else, inspire almost a superstitious awe and reverence. In the 

 fabulous ages, men would have invested it v/ith the attributes of di- 

 vinity, and would have offered to it incense to propitiate its favor. 



The Steam Engine, moreover, affords the most striking exempli- 

 fication of the natural alliance which subsists between philosophy and 

 the arts, — an alliance which, though it is so obvious to the present 

 age, and so natural in itself that, as Professor Playfair remarks, what 

 is a principle in science is a rule in art, was still scarcely dreamed of 

 before it was pointed out by Lord Bacon. As this is the united and 

 most noble production of both science and art, so no one is qualified 

 to compose a treatise on it who is not a proficient in both. Np other 

 man can comprehend it in all its vast relations ; no other can effectu- 

 ally explore the causes of the dangers that still environ it ; none can 

 with so much probability hope to find the means of obviating those 

 dangers ; none can judge so well of proposed improvements in its con- 



