Prof. Bessel on the Greenwich Observations. 295 



names of the stars, of the hour or minute of their transits, and 

 so forth, — are of no material importance whatever ; and how 

 difficult it is to avoid errors of this kind, may be inferred from 

 the circumstance of my having found about 1400 such errors 

 in Bradley's observations. [The catalogue of these errors is 

 already printed at the expense of the Board of Longitude, and 

 is to be annexed to the publication of Mayer's original obser- 

 vations, which is nearly completed.] 



The remark, that the observations at Greenwich are com- 

 monly concluded at midnight, would be of some weight, if it 

 could be proved that any thing essential is omitted by this 

 practice, which does not appear to me to be the case. The ob- 

 servations relate chiefly to the sun, the fundamental stars, the 

 moon, and the oppositions of the planets ; and it may easily 

 be discovered that these different series are exhibited with an 

 imcommon degree of perfection. Had the censor in the Phi- 

 losophical Magazine pointed out any other series of observa- 

 tions which could have beeh combined with these, so as not to 

 interfere with them, no doubt the Astronomer Royal w^ould 

 have been much obliged to him. Every thing cannot be done 

 at once in an observatory ; and if as much is effected as can be 

 wished in one respect, something must be omitted in others. 

 But to multiply observations, without any plan or object what- 

 ever, would be mere idleness. Whoever is dissatisfied imth the 

 actual riches of the Greetiwich observations wotdd do well to make 

 the attempt to excel them; he would convince himself by such an 

 experiment that the labour and patience required for doing so 

 mux:h are fully sitfficient to exhaust the powers of any one man. 



The third class of errors, relating to the meteorological in- 

 struments, I have not yet mentioned, because I think myself 

 that greater accuracy is required in this department than it 

 has hitherto been usual to observe. And if I should be allowed 

 to suggest any improvement that could be made in the obser- 

 vations at Greenwich, it would be a more correct account of 

 the meteorological instruments, and of the place in which the 

 exterior thermometer is fixed. [It may, indeed, be expected 

 with confidence that Professor Bessel's desire to possess a 

 barometer and a thermometer, correctly compared with those 

 which are employed at Greenwich, will not long be allowed to 

 remain ungratified, though it would be a subject of much sur- 

 prise on this side of the Channel if he should detect in them 

 such discordances as he is inclined to suspect.] 



[This letter has probably appeared in Professor Schuma- 

 cher's Nachrichte7i, though tlie 84th number of that interest- 

 ing collection, for which it was intended, has not yet reached 

 this country.] 



L. No- 



