344 WRITINGS OF JOSEPH HENRY. [1855 



ON THE MODE OF TESTING BUILDING MATEKIALS, 



AND AN ACCOUNT OF THE MARBLE USED IN THE EXTENSION 



OF THE UNITED STATES CAPITOL. 



(Proceedings American Association Adv. of Science, vol. ix, pp. 102-112.)* 



August 16, 1855. 



A commission was appointed by the President of the 

 United States, in November, 1851, to examine the marbles 

 which were offered for the extension of the United States 

 Capitol, which consisted of General Totten, A. J. Downing, 

 the Commissioner of Patents, the Architect, and myself. 

 Another commission was subsequently appointed, in the early 

 part of the year 1854, to repeat and extend some of the ex- 

 periments, the members of which were General Totten, 

 Professor Bache, and myself. 



A part of the results of the first commission was given in 

 a report to the Secretary of the Interior, and a detailed ac- 

 count of the whole of the investigations of these committees 

 will ultimately be presented in full in a report to Congress; 

 and I propose here merely to present some of the facts of 

 general interest, or which may be of importance to those 

 engaged in similar researches. 



Though the art of building has been practiced from the 

 earliest times, and constant demands have been made in 

 every age, for the means of determining the best materials, 

 yet the process of ascertaining the strength and durability of 

 stone appears to have received but little definite scientific 

 attention; and the members of the commission, who had 

 never before made this subject a special object of study, were 

 surprised with unforeseen difficulties at every step of their 

 progress, and came to the conclusion that the processes 

 usuially employed for solving these questions are still in a 

 very unsatisfactory state. 



It should be recollected that while the exterior materials 



* [lie-printed in Silliman's American Journal of Science, July, 1856; vol. 

 XXII, pp. 30-38. Also in the Smithsonian Report for 1856; pp. 303-310.] 



