The Three Secretaries 151 



take no stand for or against the theory ; and his remon- 

 strances were supported by those of a number of his friends 

 in Washington, members of the church which he was accus- 

 tomed to attend, who were greatly disturbed that he should 

 entertain opinions which seemed so heterodox and dangerous. 

 His attitude was never shaken, however, although he never 

 felt called upon to express his views publicly. "I am a physi- 

 cist, and not a naturalist," said he, "and it is not proper for 

 me to participate in this discussion ; but if there is any science 

 in natural history, this is the first step which has ever been 

 taken to demonstrate it." 



Much of his most careful work was in connection with eco- 

 nomic problems submitted to him individually, or as a member 

 of various commissions, by the government of the United 

 States. In 1851 he was actively concerned in the modes of 

 testing building materials, in connection with the examination 

 of marble for the extension of the United States Capitol. In 

 1855 he used the great tower of the Institution building for 

 experiments to test a new process for procuring alcohol, for 

 which a patent had been granted. 



In 1852, when the Lighthouse Board of the United States 

 was organized, President Fillmore appointed him one of its 

 members ; and on this Board he served until his death, and 

 from 1871 to 1877 was its chairman. He thus had opportunity 

 to make his famous researches on sound in relation to fog- 

 signaling, in connection with which grew up his discussion of 

 the subject with Professor Tyndall. These researches were 

 of the highest scientific value, and at the same time led to 

 immediate practical results of the greatest importance. He 

 also conducted the experiments on illuminants which resulted 

 in a complete revolution in the methods of lighthouses, re- 

 placing sperm-oil by lard-oil in 1866, which substitution, com- 

 petent authorities estimated in 1877, had already saved to the 



