SOLAR ECLIPSE, MAY (i, 188,}. 99 



I very much regret that the excellent photographic apparatus constructed under the direction 

 of Prof. W. Hakkness, (J. S. N., for the Naval Oliscrvatory, was not utilized 0:1 this expedition. 

 From the results obtained with it in 1878, even before its moditication into its present form, I have 

 no doubt but that observations of great value could have been secured. As it was, the entire 

 field of iihotography was left to the English party wliich accompaTiied our own, and I must refer 

 to the memorandum of Mr. Lawbance, which accompanies this rei>ort, for a preliminary account 

 of their preparations and valuable results. Photography of the corona, etc., was also employed in 

 a very successful way by the French expedition under M. Janssen. 



The plan of the American party proper- comprehended — 



(A.) A search for the interior planet (or planets) Vulcan, reported by Professor Watson and 

 also by J'rofessor Swift. This was assigned by your committee to me. 



(B.) Spectroscopic observations of the inner and outer corona. 



This was undertaken by four observers, namely Dr. Hastings, Mi-. Kockwell, Mr. TJi'Ton, 

 and Ensign Brown. The general plan of the specti-oscopic and polariscopic observations was 

 discussed by Dr. Hastings and myself with the other observers, but the entire credit for the 

 details of the observations belongs to Dr. Hastings and to the observers themselves who were 

 placed under his directions. 



(C.) Polariscopic observations of the corona. 



At my request Dr. Hastings brought with him the polariscope which he used at the eclipse 

 of 1878, for the purpose of attaching it to one of the spare telescopes of the party, and it was 

 my hope that a satisfactory set of observations might be obtained, especially because the observa- 

 tions with this instrument in 1878 had led to the conclusion of tangential polarization. 



Mr. Preston was placed under the exclusive direction of Dr. Hastings for this duty, his 

 observations to be made during that i^art of totality after his observations of the time of second 

 contact and before his observation of third contact. 



The telescope was pointed by Midshipman Doyle, and during totality Mr. Preston made 11- 

 pointings. When these were reduced they showed that the apparatus itself, /. e., the c )mbination 

 of the telescope and the polariscope, was not suitable to its object, as a subseriueiit examination 

 convinced Dr. Hastings and myself. I regret that this should not have been found out before- 

 hand, so that the services of such a competent observer as Mr. Preston might have been utilized. 

 The observations are not here printed. 



(D.) Telescopic examination of the details of the inner corona. 



This was made by Dr. W. S. Dixon, U. S. JST., with the 3.i-inch Clark telescope lent to us 

 by the Nautical Almanac office. A drawing of the corona with a descriptiou is given in Dr. 

 Dixon's report. 



(E.) Observation of the contacts. 



The^rs^ contact was observed by Messrs. Upton, Preston, and Brown. 



The second by Mr. Preston. 



The third by Mr. Preston. 



The fourth by Messrs. Holden, Rockwell, Upton, Presion, and Brown. 



The observation of the contacts was made entirely subordinate to more important work. 



(F.) The determination of the latitude. 



This was determined on four nights by IG pairs of stars, by Talcott's method, by Messrs. 

 Preston and Brown. Mr. Upton also determined a preliminary value with the sextant. 



^G.) The determination of the longitude. 



