228 Boyal Astronomical Society. 



manac. The number of observations of the stars in the catalogue is 

 12007, or rather more than 9 observations for each star, on an average. 



The partial mean places appear to be as close to each other, or 

 nearly so, as those of the Greenwich observations. It follows, from 

 Mr. Wrottesley's method of deducing the clock error for each star 

 from one, two, or more standards which are near it, that the acci- 

 dental errors are greater than he would have had, if he had used all 

 the standard stars for his clock error ; but, as it is, a greatest differ- 

 ence from the mean of ten or twelve observations exceeding O'^'S 

 is not common, which leaves only a small uncertainty upon the 

 final result; especially since this difference, being the sum of two 

 independent errors of observation, viz. that of the standard deter- 

 mining star and that of the catalogue star, may be expected to have 

 little effect in the mean of several observations. Indeed, there 

 can be no doubt, that this catalogue of Mr. Wrottesley's may be 

 used for all purposes, with nearly, if not altogether, the same con- 

 fidence as the fundamental catalogue from which it is derived. 



Of the means taken to insure accuracy in the reductions, Mr. 

 Wrottesley has given a very satisfactory account, and that these 

 means have been effectual, he has stated the following proof. In 

 Mr. Wrottesley's catalogue are 138 stars observed and reduced by 

 Professor Airy in the Cambridge observations. *' Of these, 46 agree 

 within 0'-05; 89 within 0^-10; 115 within 0«-15 j 131 within 0-20; 

 and only one differs so much as 0'*30." We have a further and in- 

 dependent proof of the correctness of this catalogue in the Re- 

 marks (appended by Mr. Baily) on the differences of I'-O and up- 

 wards, between the catalogue of Mr. Wrottesley and that of the 

 Astronomical Society. It is known to the Society, that our cata- 

 logue has been pretty nearly reobserved by Mr. Taylor at Madras, 

 and very well observed, though, unfortunately,very few copies [of Mr. 

 Taylor's catalogue] have found their way into the hands of English 

 astronomers. There are 29 stars having such differences, of which 

 24- have been observed by Mr. Taylor, and in every instance his result 

 confirms that of Mr. Wrottesley. Whether these anomalies are to be 

 attributed to errors in the catalogues of Bradley or Piazzi (for Mr. 

 Baily has examined the computations by which our catalogue is de- 

 duced from theirs), or whether there is some irregular motion in the 

 stars themselves, time will show. It is from such undertakings as this 

 of Mr. Wrottesley, and so executed, that we must expect to fix the 

 state of the heavens at certain epochs, and so prepare the data for 

 future speculation and future discovery. For such inquiries, Mr. 

 Wrottesley's present of the original transit books, to which the 

 partial mean places serve as a complete index, will be of great and 

 permanent value. 



There are several remarks which deserve, and doubtless will re- 

 ceive, the attention of practical astronomers, but which would be 

 here out of place. We must not, however, omit mentioning that 

 the whole work has been performed, to use Mr. Wrottesley's words, 

 " without any foreign aid," by himself, and, under his superintend- 

 ence, by his assistant Mr. John Hartnup; upon whom, indeed, in 



