282 BULLETIN OF THE 



Professor Elie Wartraan, of Lausanne, in the Scientific Memoirs,) 

 supplied original observations on this interesting department of 

 the physiology of vision. 



Miscellaneous Contrihutions. — Henry's miscellaneous contri- 

 butions to physical science are so numerous and varied, that only 

 a brief allusion to some of them can be afforded. In 1829, he 

 published quite an elaborate " Topographical sketch of the State 

 of New York, designed chiefly to show the general elevations 

 and depressions of its surface."* And in later years he devoted 

 much attention to physical geography. He performed at various 

 times, a good deal of chemical work (chiefly of an analytical 

 character). — first as Dr. T. Romeyn Beck's assistant,! and after- 

 ward independently, as well as mediately in directing his own 

 pupils and assistants. In 1833, he devised an improvement of 

 Wollaston's mechanical scale of the chemical equivalents, for the 

 benefit of his pupils in chemistry: — a contrivance which was 

 much used and highly appreciated at the' time. 



The suggestion had been thrown out by more than one astro- 

 nomer, that carefully timed observations on characteristic meteors 

 or " shooting-stars" might be made available for determining 

 differences of longitude between the stations of observation.! 

 For many years however the proposition bad been generally re- 

 garded as offering rather a speculative than a practical method of 

 solving a problem of so great nicety. Henry in concert with his 

 brother-in-law, Professor Alexander, and with his friend Professor 

 Bache, determined to ascertain by actual trial the availability and 

 value of the system. On the 25th of November, 1835, Professor 

 Bache observing at his residence in Philadelphia (assisted by 

 Professor J. P. Espy,) — simultaneously with Professor Henry 

 and Professor Alexander, at the Philosophical Hall at Princeton, 

 they obtained seven co-incidences: — the instant of disappearance 

 of the meteor being in each case selected as the most accurately 

 attainable epoch. These seven observations (whose greatest dis- 

 crepancies amounted to but a trifle over 3 seconds) gave a mean 

 result of 2 minutes 0.61 second (time longitude) differing only 



■" Trans. Albany Institute, vol. i. pp. 87-112, 



f "Henry was tlien Dr. Beck's chemical aj^sistant, and already an ad- 

 mirable experimentalist." Address before tbe Albany Institute, by Dr. 

 O. Meads, May 25, 1871. {Tmns. Albany Tnstit. vol. vii. p. 21.) 



\ ■' Tile merit of first suggesting tbe use of shooting stars and fire-ball3 

 as signals for the determination of longitudes is claimed by Dr. (.)lliers and 

 tire German astronomers for Benzenberg, who published a woik on the 

 subject in 1802. Mr. Bailey liowever has pointed out a paper publishud 

 by Dr. Maskelyne twenty years previously, in wliich that illustrious 

 astronomer calls attention to the subject, and distinctly points out this 

 application of the phenomena.'' This was dated Greenwich, November 

 6lh, 1783. (Z. E. D. Phil. Mag. 1841, vol. xix. p. 554.) 



56 



