334 BULLETIN OF THE 



ratus devised by Mr. Joseph Saxton, was capable of distinguish- 

 ing by 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 Smith- 

 sonian 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 oppor- 

 tunity was seized by Henry, at the termination of the investiga- 

 tion, to apply the same delicate apparatus to the determination 

 of the polarized or magnetic expansion. 



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 fraternal 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 

 1861, 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 ac- 

 knowledgement of the wise counsels and valuable services of Dr. 

 Bache as one of the Regents of the Smithsonian Institution for 

 nearly twenty years, he observed : "To say that he assisted in 

 shaping the policy of the establishment would not be enough. 

 It was almost exclusively through his predominating influence 

 that the policy which has given the Institution its present celeb- 

 rity, was after much opposition finally adopted. . . . Nor 

 would it be possible for him [the speaker] to abstain from ac- 

 knowledging with heart-felt emotion, that he was from first to 

 last supported and sustained in his difficult position by the fra- 

 ternal sympathy, the prudent counsel, and the unwavering friend- 

 ship of the lamented deceased."* 



Many minor contributions in various fields of scientific obser- 

 vation, must here be omitted : but it would be inexcusable, in 

 this place and on this occasion, to neglect a reference to the 

 active part he took in the organization and advancement of this 

 Society ;t and the unflagging interest ever exhibited in its pro- 

 ceedings, from the date of its convocation, March 13th, 1871, to 

 that of his last illness. All here remember with what punctu- 

 ality he attended the meetings — whether of the executive com- 

 mittee or of the society, undeterred by inclemencies of the 

 we'ather which kept away many much younger members. All 



* Biographical Memoirs, Nat. Acad. Sci. vol. i. pp. 181-212. Repub- 

 lished in the Smithsonian Report for 1870, pp. 91-116. The father of Prof. 

 Bache— Richard Bache, was a sou of the only daughter of the illustrious 

 Benjamin Franklin. 



t The Philosophical Society of Washiogton. 



108 



