﻿B. A. Gould — Determinations of Stellar Positions. 371 



puted, and the results added to those from the first three plates 

 in the memoir already written. 



Various circumstances combined to delay the publication, 

 chief among them being what seemed to me a manifest impro- 

 priety in printing the results derived from photographs and 

 measurements made by Mr. Rutherfurd, and by his own 

 methods, before some account of these methods should have 

 been published by him. His communication on the subject 

 had been made to the National Academy immediately previous 

 to my own, but was not yet in such form as he desired for pub- 

 lication. 



The result showed a very remarkable accordance with Bes- 

 sel's determination for 1840, although the total amount of rela- 

 tive proper motion during the elapsed 26 years, was comprised 

 in the differences. 



This memoir still remains in its original form, but unpub- 

 lished ; the results being deduced from 24 photographic impres- 

 sions. 



In the next year, 1868, I had the gratification of receiving 

 from Mr. Rutherfurd the results of his measurements of 32 

 stars of the cluster Prsesepe, derived from 11 impressions. 

 These were computed in the same way that those of the 

 Pleiades had been, and an analogous memoir upon this cluster 

 was prepared for the National Academy. 



Before leaving the country, early in 1870, I gave these two 

 memoirs to Mr. Rutherfurd, with the request that he would 

 send them to the printer at the same time with his own paper, 

 already mentioned; but not before that. The condition of his 

 health prevented him from attending to the matter for some 

 time; and in the interval, he arrived at the unpleasant discov- 

 ery that the screw of his micrometer had suffered from wear, 

 and to an extent which led him to fear a want of that accuracy 

 of which the method is susceptible, and which he hoped to see 

 demonstrated by its very first applications. 



Notwithstanding this possible blemish, it seems to me that 

 the results ought to be now made public in their original form, 

 after due mention of the circumstances ; and it is among my 

 hopes to be able soon to publish these two memoirs from the 

 original manuscript of so many years ago. 



The method was received with manifest distrust and disre- 

 gard abroad; and, as was but natural for so essential a devia- 

 tion from former methods, very many grounds of criticism and 

 objection were brought up. One of the principal of these was 

 the possible distortion of the collodion film, after receiving the 

 impressions and before the measurements ; but Mr. Ruther- 

 furd speedily disposed of this point, at least so far as the albu- 

 minized plates are concerned ; and, moreover, the combination 



