136 MEMOIES OF THE NATIONAL ACADEMY OF SCIENCES. 



Ou tlie other, liaud, the origiual pencil record of the time is plain, and there can be no doubt that 



the time was noted as given above. 



I have the honor to be, very respectfully, yours, 



WINSLOW UPTON. 



REPORT OF ENSIGN S. J. BROWN, U. S. NAVY. 



U. S. S. Haktford, at Sea, 



(Long. 147° W., lat. 2° S.) 

 Prof. Edward S. Holden: 



SiE: Having been detailed by the Navy Department as a member of the U. S. Solar Eclipse 

 Expedition, in accordance with the instructions contained in my orders, I conferred in regard to 

 my duties with Prof. J. H. C. Coffin, U. S. Navy, secretary of the committee of the National Acad- 

 emy of Sciences on the Solar Eclipse. I was given written instructions to the effect that the com- 

 mittee desired me, in all my scientific work, to place myself under your instruction and directions 

 as chief and scientific head of the expedition. 



In pursuance of those instructions I have the pleasure to submit to you the report of my work. 



I left the Naval Observatory February 28, taking with me the following instruments: 4-inch 

 comet-seeker, 42-iuch focal length ; Si-inch equatorial, 42-inch focal length ; sextant and artificial 

 horizon ; two chronometers. 



By your direction I took charge of all the chronometers in the party, intending to use them in 

 determining the chronometric longitude of the place selected for the observations. But after leav- 

 ing Callao, Peru, on account of sickness and great prostration, I gave up the care of the chronom- 

 eters to Mr. Upton. Subsequently my duties connected with the gravity experiments and obser- 

 vations for latitude took up my time so completely that I could not resume charge of them. 



With the comet-seeker I had planned to sweep^during totality for intra-mercurial planets. To 

 aid iu this, I had constructed a chart, embracing stars of the 7.5 magnitude, and extending 32° in 

 E. A., and 10° in declination in the neighborhood of the ecli^jsed suu. But after a full discussion 

 with yourself and Dr. Hastings, as to the greater importance of certain spectroscopic observa- 

 tions which you wished to have made, I decided, in deference to your wishes, to use instead an 

 integrating spectroscope devised by Dr. Hastings. 



My work ou the island comprised, (I), siiectroscojiic observations ; (II), computation of time 

 of contacts and observations of the first and fourth ; (III), pendulum observations in conjunction 

 with Mr. E. D. Preston, U. S. Coast and Geodetic Survey, iucluding observations for latitude. 



I. Spectroscopic Observations. 



In these observations I used an integrating spectroscope with an effective aperture of \% inch 

 and a magnifying power of 9. During the passage from Callao to the Island, I used the spectro- 

 scope frequently to familiarize myself with relative positions of the Fraunhofer lines. After our 

 arrival, the effectiveness of the instrument was much increased by placing a double concave lens 

 between the slit and the objective of the collimator. The instrument was devised by Dr. C. S. 

 Hastings, who was in charge of all spectroscopic work, and a full description of it will be found in 

 his report. It was attached to the 3-inch equatorial,* which was pointed by Passed Assistant Sur- 

 geon W. S. Dixon, U. S. Navy, who used it at the same time on making sketches of the corona. 



* Till! instrument used by Mr. Brown was strapped to the outside of the tube of Dr. DixON'S telescope, which 

 was constantly pointed at the sun's center. — E. S. H. 



