144 CARNEGIE INSTITUTION 



research indicated in 3'our "confidential" paper are important and 

 ought to be followed up in some concerted manner ; but I own to 

 some doubt whether it would be best that all that research should 

 be concentrated at any one, two, or even three stations. Coopera- 

 tion between workers widely enough separated to secure nearly con- 

 tinuous observation might be better, unless some locality can be 

 found where observations are practicable all the time, and I know of 

 no such locality, in the United States, at least. Still it is obvious 

 that, given the "ideal" director with adequate means at his dis- 

 posal, there would be great advantages in the concentration, perhaps 

 quite sufficient to overbalance the disadvantages. 



As regards my experience at Sherman, it did not indicate any 

 advantages as to average aerial conditions over Hanover and Prince- 

 ton, but during my six weeks' stay there (I think it was six weeks) 

 there were two or three magnificent nights, when the conditions 

 were better than I ever saw them here (one night here, perhaps, 

 excepted, or rather a few hours that night). For solar observa- 

 tions, however, the conditions from half an hour after sunrise till 

 9 or 10 a. m. were fine more than half the time. About 1 1 it 

 usually began to cloud up, and in the afternoon thunder storms 

 were in order till 8 or 9 p. m. , and for some hours afterw T ard the 

 air, though very transparent, was very unsteady. The seeing may 

 have been good after midnight, but I did not examine it often, as 

 my work on the sun gave my eyes all I could safely do with them. 



Of course, my statement as to the behavior of the weather can 

 not safely be taken as applicable to all years and months. It was 

 in the months of July and August, 1872, that my observations were 

 made, and I remember that some of the few residents of Sherman 

 said that the conditions were unusual for those two months on 

 account of the unusual amount of snowfall the preceding winter on 

 the mountains west and south of Sherman ; but from all I can learn 

 I should think there was much more likelihood of finding better 

 average seeing not very far from the sea, as in southern California. 



I ought to add that undoubtedly an outburst of vigorous solar 

 activity on the sun's limb from August 1 to 6 had a great deal to 

 do with my success in finding new chromosphere lines. During the 

 first three weeks of work I made little headway and was much dis- 

 couraged. When I began to get up and go to work at 5 or 5.30 

 a. m. things went better, but the days I have mentioned, August 

 2-5, gave me fully half my harvest. 



