244 THE POPULAR SCIENCE MONTHLY. 



in America has not yielded to masonry ; even in the erection of brick 

 or stone houses, the former has a greater share of work, the latter 

 doino- scarcely anything beyond building the outside walls. In Ameri- 

 can brick or stone houses, about twenty-five times more wood than in 

 European is used. This may have its evils, wood being subject to 

 ignition and not being naturally so endurable as other materials ; but 

 it will not take long for Americans to invent some process by means 

 of which wood may be rendered incombustible, and as solid as stone ; 

 something in this direction, we believe, has been done already. The 

 bold centering of domes and the slender elevation of steeples on skele- 

 tons of wood, as carried in this country, command the attention of for- 

 eigners ; there are a dash and lightness in those works that bespeak the 

 skill of American carpenters. The mechanical performances of " Sar- 

 danapalus" and other plays can not be overlooked in an article refer- 

 ring to carpentry. Nor can we omit to record that American ship-build- 

 ing compares favorably with that of any nation, the English included. 

 Yet all this becomes a trifle if we consider American wood bridges. 

 The Schuylkill bridge, built by Wernwag at the beginning of this cen- 

 tury at Philadelphia a suspension-bridge, 340 feet long can not but 

 be considered a marvel of art. This bridge would not yield save 

 under a weight of 1,275 pounds per square inch of the lower chord ! 

 During the civil war the constructions of the Federal troops aston- 

 ished the world ; to the rapidity with which new bridges were built in 

 a truly artistic and scientific manner, and to the skill of their archi- 

 tects, engineers, and carpenters is due, in great part, the success of the 

 Northern forces. 



Carpenters appear to us as the vanguard of progress, the initiators 

 of all movement toward the supply of mankind's first wants. How- 

 ever incomplete, we trust that our sketch will be deemed suggestive 

 enough to show that their history is worthy of being diffused through 

 the medium of a popular publication. 



THE AVAILABILITY OF ENERGY. 



By W. D. MILLER, B. A. 



IT follows, as a direct consequence of the most usual definition of 

 matter as "the vehicle of energy," and is also arrived at from 

 experience, that energy never does and never can manifest itself except 

 in connection with matter. And, although we could readily conceive 

 of, and in fact see many instances of, matter without energy, yet no 

 person of sound intelligence, or, as said Newton, " no one with a 

 competent faculty of thinking," could for a moment entertain the idea 

 of energy without matter ; and we naturally suspect that anything 



