1825.] Scientific Notices^^Miscellaneous. 391 



which Mr. Olufsen has computed the declinations of the funda- 

 mental starsy'as published in Nachrichten, No. 73, from the 

 Greenwich observations for 1822. . ' 



The greater number of the errors which feave been pointed 

 out by the censor, are merely accidental errors of the pen. 

 Errors of this kind are certainly disagreeable, and it would b^ 

 better if they could be entirely avoided; but since all coUeqtions 

 of observations in existence do contain such errors, they clearly 

 appear to be unavoidable. The first class of errors mentioned 

 in the Philosophical Magazine contains the cases in which the 

 mean deduced from the readings of the two microscopes A and 

 B differs from the column in which that mean is assigned. Since 

 there must be some manifest oversight in all these cases, it 

 may sometimes be difficult to determine whether it is in the 

 readings or in the mean assigned, but it will, in geneml, be easy 

 to distinguish, fiom the preceding or following observations of 

 the same star, where the error lies. ; ,. , , r,)^..; 



The second class contains the differences between different 

 records of the same observation. These must be errors in the 

 copies sent to the press, and not in the readings of the mi- 

 croscopes ; and they may generally be corrected by a compa- 

 rison of the two passages : they sometimes extend to whole 

 degrees, or to the tens of the minutes, and are then of no 

 importance ; for example, in the observations of Procyon, the 



,16 



micrometer wires, as they are deduced from different observa- 

 tions of the same star. These are often dependent on errors ^of 

 the pen, as in the observation of Capella on the 7th February, 

 and in that of Sirius on the 8th, where there are errors of 5'*^ 

 and of 4^' respectively in the fourth wire; frequently also they 

 arise from inaccuracies of observation. In the former case 

 they ere of no consequence whatever, being easily detected ^t 

 first sight; in the latter they are fiindamental imperfection's ; 

 but such imperfections are inseparable from the nature 'of 

 observations, and it would be ridiculous to 'expect from 'an 

 astronomer that he should perform impossibilities. A/l registers 

 of observations exhibit inaccuracies of this kind, and if any 

 should be produced without them, it might with confidence be 

 asserted to be a forgery. The diligence of the astrbndilief is 

 proved, not by the perfect agreement in his tenths of seconds, 

 but by the magnitude of his mean or probable ^ error ; and it 

 would probably be difficult for the critic to 'bi*ovb'^'t^| ifi?^ yfror 

 is much greater in the Greenwich observationi,tHWtH^^ nature 

 of the instruments renders unavoidable." '-^ KfJ ^M) isbnj . 

 The errors of the Jifth class, which compi^eftehdi^'^^fe'* W- 



