178 PHOTOGEAPHY IN ASTRONOMICAL RESEARCH. 



produced bv Messrs. Repsold, Avith the astonishing resuh tliat the 

 troul^les from personal etpiation. Avhirh luive so long- been a difficulty 

 in all fundamental work, have practically disap])eared. 



This beautiful invention has i)lace(l the eye once more in a position 

 actually su])erior to the })hotogra})hic plate, for with the eye we can 

 obser^'e stars in daylight, and so secure information of great impor- 

 tance, whereas no photographic method of doing this has as yet been 

 devised. And there is also the fact that for faint stars a long 

 exposure would be re(|uire(l for what the eye can accom|)lish in a few 

 seconds. 



Thus in one or two astronomic channels the etlects of the rising 

 tide of photography have scarcely yet been felt : but iuto all the others 

 it has swept ^^ ith ever-growing force. Looking back over the thirty 

 years of advance, we may be Avell satisfied. With more funds, and 

 especially with more men, no doul)t more could have been done: let 

 us even admit that we might have done better with the same funds 

 and the same limited staif. But on the whole we have been fortunate. 

 At a critical time, when we might have felt the want of larger endow- 

 ments acutely, the need was almost anticipated by a stream of bene- 

 faction. If tliis stream had its chief source in the United States, its 

 beneficial effects have poured over the whole world, and induced cur- 

 rents have begun to flow elsewhere. We may reflect with thankful- 

 ness how much hardei" our a(hance might have been but for the noble 

 gifts to the Harvard, the Ijick, and the Yerkes observatories, and 

 earnestly hope that the cheerful expectations of a great American 

 astronomer, that these are but the foreshadowing of much larger gifts 

 to science, may be adequately realized. 



May I now turn to one or two of the problems with which this new 

 development of our work has brought us face to face? They are 

 numerous and serious, and it is impossible to consider many of them, 

 perhaps even the most imj)ortant of theui. One of the most pressing 

 is the ])roblem of rendering generally accessible the vast accunnda- 

 tions of nuiterial for study that have been suddenly thrust upon our 

 atteution. Hoav are our photographs to l)e stored, preserved, and 

 l)ul)lished? P'ven now troubles liaA'e gathered, and time will only 

 uudtiply them. It is many yeai-s since Proft^ssor IMckering drew 

 attention to the difficulties in storing the i^hotographic plates taken 

 at the Harvard ( )bs(M-vatory. \\'hen many thousauds of i)h()t()graphs 

 ha\e beeu accuuudated. uot ouly the space they occupy, but the actual 

 weight of glass is an embarrassuieut. And ther(» seems to be no doubt 

 conceruing the duty of accuuudation. JNIay I confess an early aud 

 mistaken view which 1 foiMuulat(>d on this inattei'? I reasoned thus: 

 The proper mouient for making use of a ])holograph takeu last night 

 is to-day. It is useless to defer the exauiiuatiou uutil to-uiorrow, for 

 there will then be new photographs claiuiing attention. Hence it is 



