﻿374 B. A, Gould — Determinations of Stellar Positions. 



by 12 cm . In their present form they are of course of small 

 value for scientific use, inasmuch as the stars are too crowded 

 for their configurations to be easily perceived ; and, although 

 these two series form in fact maps of considerable regions in 

 the sky, still the record is of a very perishable nature, and of 

 small avail for use by astronomers until it shall have been 

 translated into an enduring and numerical form by micrometric 

 measurement. 



In this connection I may say that one of the greatest of my 

 present anxieties regarding the Cordoba photographs arises 

 from a discovery of the ease with which the collodion or gela- 

 tine film may become detached from the glass. The Argen- 

 tine Government has assigned a moderate sum for the prosecu- 

 tion of the measurements, and with this some progress has 

 already been made. It is but right to add that the full amount 

 was given for which I asked. Still it is now quite inadequate, 

 in consequence of the unfortunate depreciation of the national 

 currency ; and, in the present financial crisis there, I cannot 

 reasonably expect more. Yet this matter of prompt measure- 

 ments appears to me at present much more important than it 

 did while I was unaware of the facility with which the film can 

 blister and peel. 



In 1883, after Mr. Common's brilliant success in photograph- 

 ing nebulas with his great three-foot reflector, he proposed to 

 me a joint arrangement for photographing the whole heavens. 

 My work at Cordoba was so near its close that it was out of the 

 question to undertake anything new; but the immense labor 

 requisite for the measurement of the plates would, under any 

 circumstances, have tended to deter me. It is an undertaking 

 demanding the joint energy, application, and material resources 

 of a large number of persons, if the results are to be made 

 available for astronomical use : indeed, I see no other astro- 

 nomical value in the unmeasured photographs than the possi- 

 bility of confirming at some future epoch the existence of rela- 

 tive motion previously detected or made probable by some 

 other investigation. 



Since then, the process of photographic charting is said to 

 have been systematically undertaken by the Brothers Henry, 

 at Paris. I have seen none of their plates; but their sharp- 

 ness is highly spoken of, and the work appears to be prose- 

 cuted with much skill and very sensitive plates. There can of 

 course be no question as to the value of any permanent record 

 whatsoever, corresponding to a known date; yet I cannot feel 

 that an essential advance is likely to be made in this way until 

 the photographic record shall have been brought within the 

 range of numerical expression. 



The measurements of the Cordoba photographs, thus far 



