330 MEMORIAL OF JOSEPH HENRY. 



the varying length, under different temperatures, of the measuring 

 apparatus of the base lines of the United States Coast Survey." * 

 This wonderfully microscopic measuring apparatus devised by 

 Mr. Joseph Saxton, was capable of distinguishing ( by means of the 

 light-ray index of its contact reflector,) a dimension equal to a half 

 wave-length of average light, or the 100,000th part of an inch. 

 The long under-ground vaults of the Smithsonian building having 

 been selected as a suitable place for the precise verification of the 

 residual co-efficient of compensated temperature expansion of the 

 base rods of the Survey, the opportunity was seized by Henry, at 

 the termination of the investigation, to apply the same delicate 

 apparatus to the determination of the polarized or magnetic expan- 

 sion. The results of these delicate and interesting investigations 

 are lost to the world. 



In less than six years from the time of these researches, he was 

 called on to mourn the death of his life-long intimate and honored 

 friend, who had always exhibited so brotherly a sympathy and 

 co-operation with his. own varied labors. In consequence of this 

 event the death of his friend Professor A. Dallas Bache in 1867, 

 Henry was chosen in 1868, to be his successor as President of the 

 National Academy of Sciences. At the request of that body, he 

 prepared a eulogy of his friend the late President, which was read 

 before the Academy April 16th, 1869. In grateful acknowledg- 

 ment of the wise counsels and valuable services of Dr. Bache as one 

 of the Smithsonian Regents, he observed: "In 1846 he had been 

 named in the act of incorporation as one of the Regents of the 

 Smithsonian Institution, and by successive re-election was continued 

 by Congress in this office until his death, a period of nearly twenty 

 years. To say that he assisted in shaping the policy of the estab- 

 lishment would not be enough. It was almost exclusively through 

 his predominating influence that the policy which has given the 

 Institution its present celebrity, was after much opposition finally 

 adopted. - - - Professor Bache with persistent firmness tem- 

 pered by his usual moderation, advocated the appropriation of the 

 proceeds of the funds principally to the plan set forth in the first 



* Smithsonian Report for 1861, p. 38. 



