406 WRITINGS OF JOSEPH HENRY. [1856 



of iron and of glass requires an entirely different style 

 from that which sprung from the rocks of Egypt, the masses 

 of marble with which the lintels of the Grecian temples 

 were formed, or the introduction of brick by the Romans. 



The great tenacity of iron, and its power of resistance to 

 crushing, should suggest for it, as a building material, a far 

 more slender and apparently lighter arrangement of parts. 

 An entire building of iron, fashioned in imitation of stone, 

 might be erected at small exercise of invention on the part 

 of the architect, but would do little credit to his truthful- 

 ness or originality. The same may be said of our modern 

 pasteboard edifices, in which, with their battlements, towers, 

 pinnacles, "fretted roofs and long drawn aisles," cheap and 

 transient magnificence is produced by painted wood or 

 decorated plaster. 



Lecture-room Acoustics. — To return to the subject of acous- 

 tics, as applied to apartments intended for public speaking : 

 While sound, in connection with its analogies to light, 

 and in its abstract principles, has been investigated within 

 the last fifty years with a rich harvest of results, few 

 attempts have been successfully made to apply these princi- 

 ples to practical purposes. Though we may have a clear 

 conception of the simple operation of a law of nature, yet 

 when the conditions are varied, and the actions multiplied, 

 the results frequently transcend our powers of logic, and 

 we are obliged to appeal to experiment and observation to 

 assist in deducing new consequences, as well as to verify 

 those which have been arrived at by mathematical deduc- 

 tion. Furthermore, though we may know the manner in 

 which a cause acts to produce a given effect, yet in all cases 

 we are obliged to resort to actual experiment to ascertain 

 the measure of effect under given conditions. 



The science of acoustics as applied to buildings, perhaps 

 more than any other, requires this union of scientific prin- 

 ciples with experimental deductions. While on the one 

 band, the application of simple deductions from the estab- 

 lished principles of acoustics would be unsafe from a want 

 of knowledge of the constants which enter into our formulae, 



