176 PHOTOGRAPHY TN ASTRONOMICAL RP]SEARCH. 



carefully before we can certainly accuse our ijlu)toi>rai)lis of a failure 

 in accuracy. Nevertheless, there are indications that Ave may be 

 near the limit of accuracy even now. Examination of the reseau 

 lines on various plates appears to show small displacements for 

 which no cause has yet been assigned; and the end of our tether 

 may not be far away. But as yet we have not been pulled up short, 

 and there is hope that the warning- nuiy be, as on one or two previous 

 occasions, a false alarm. 



Such being the accuracy of the photographic method, it is sur- 

 prising that it should not as yet have been more fully adopted in 

 that field of work where accuracy is of the greatest importance — 

 Jiamelr, in what is called fundamental Avork, Avith the transit 

 circle or other meridian instruments. The adoption of ucav methods 

 is ahvays a sIoav process, and there are at least tAvo classes of diffi- 

 culties Avhich hinder it. The first class has it origin in the in- 

 stinct Iac conservatism of human nature, Avherein men of science 

 difi'er little from their felloAvs. The second has to do Avith aA^ailable 

 capital; and in this respect Ave are distinctly at a disadvantage 

 compared Avith othei' men; for when a ncAV instrument of general 

 utility is iuAented at once a large amount of capital is invested in 

 Avorking out the details and improving them to th(> utmost, Avhereas 

 for a scientific instrument no such funds are available. Think. 

 for instance, of the money spent in perfecting the bicycle, and the 

 time occupied in deA'eloping it from the earliest forms to those 

 Avith Avhich Ave are noAv familiar — from the '' bone shaker " of the 

 sixties through the high bicycle Avhich Ave saw tAventy A'ears ago 

 to the modern nuichine. Think, too. how totally unexpected ha\e 

 l)een some of the incidents in the history of this machine, such as 

 the introduction of pneumatic tires. In the case of such an instru- 

 ment, noAV universally adopted, if rapid development coiihl have 

 heen secured l)y expenditure of money and brains, surely enough 

 of both counnodities Avere forthcoming to attain that end; and yet 

 simplicity and finality have i)r()habiy not yet been attained in a 

 pei'iod of thirty yeai's. Wlien Ave comi)are the snuill amount of 

 money and especially the small number of persons that can be de- 

 A^ited to the pei-feclion of a new scientific method, such as the use of 

 phot()gra})hy in astronomy, it will excite little surprise that progress 

 during the same ]x>riod of thirty years has been sloAver. Tn com- 

 merce old machines can be thrown on the sci'ap heap when iini)rove- 

 ments suggest themselves; but who can all'oi-d to throw aAvay an old 

 transit circh'^ The A'ery fact that it has been in use for many years 

 renders its continued use in each succeeding year the more inii)ortant 

 from considerations of continuity. 



It is doubtless for such reasons as these that little has yet been done 

 in the Avay of utilizing ])h()tograi)hy for meridian obserA^ation. 



