124 REPOET OF THE SECRETARY. 



edge of the sun, respectively. Preliminary experiments indicate an absorp- 

 tion i)rogressively increasing toward the shorter wave lengths, so that 

 curves taken with equal slit widths, while of nearly equal height at about 

 2 /<, would exhibit nearly twice as much energy from the sun's center as from 

 near the limb in the visible portion of the spectrum. So far as is yet deter- 

 mined there is no certainly discernible selective absorption for different 

 narrow bands besides the gradual alteration of absorption just alluded to, 

 Imt the experiments are as yet inconclusive as regards this point. 



(3) Eclipse expedition to Sumatra. — It will be recalled that the observa- 

 tions of last year's eclipse by the Smithsonian expedition raised interesting 

 questions as to the existence of intramercurial planets and as to the 

 nature of the coronal radiations. So far did the interest in these problems 

 extend that it was thought worth while to send an expedition from the 

 Astrophysical Observatory to Sumatra to observe the total eclipse of May 

 18, 1901, and to repeat and extend the bolometric observations on the 

 coronal radiation and the photographic observations for possible intra- 

 mercurial planets. This expedition left Washington February 5, 1901; 

 reached Padang, Sumatra, April 4; occupied the station selected (at Solok) , 

 April 1 1 ; and left Sumatra May 28. The personnel consisted of C. G. Abbot, 

 Aid Acting in Charge, and P. A. Draper, temporary assistant. Ap])aratus 

 weighing about 4,000 pounds was taken, including the 8-inch equatorial 

 telescope mounting with coelostat. Through the good offices of the AVar 

 Department the voyages from San Francisco to Manila and the return 

 were made upon army transports, while the expedition was conveyed from 

 Manila to Padang and return upon the United States naval vessel Gen. 

 A lava, which also conveyed the expedition from the United States Naval 

 Observatory. It is a pleasure to remember the hospitality and friendliness 

 of the officers of this vessel toward us. Within Sumatra the expedition 

 was given free transportation upon the government railway, and indeed it 

 would be hard to acknowledge sufficiently the assistance and courtesy 

 received at the hands of the Dutch. I wish ('Si)ecially, however, to make 

 mention of the great kindness and helpfulness of the United States con- 

 sular agent at Padang, Mr. Cornelius G. Veth, who spared neither time 

 nor expense in our behalf. The most cordial relations existed between the 

 Smithsonian expedition and that of the United States Naval Observatory, 

 such mutual assistance as could l)e afforded being freely interchanged. 



Solok, Sumatra, the point selected for the observations, is a fair-sized 

 town of mostly native inhabitants, but the seat of a Dutch residency. We 

 found quarters in a small hotel, and an abandoned fort near the hotel was 

 placed at our disposal for the observing station. This fort was shared with 

 the larger party of the Naval Observatory, and its large rooms and inclos- 

 ing walls, together with the sufficiently large level inclosure, made it an 

 ideal station. Several years' meteorological observations having especial 

 reference to the eclipse had indicated that Solok had at least as good 

 chance of fair weather as any place in the island, and as the day of the 

 eclipse approached we found from our own observations through the month 

 of May that the chances for a fair sky around the sun at the hour of the 

 eclipse were fully two to one. So far were these (chances superior to those 

 of Fort de Kock, a minor station near the edge of the shadow, occupied by 



