CHAP, vi.] To J. F. W. HerschtL 197 



one to whom 1885, viz., 2nd and 3rd class, out of the 

 2500, can be visible in your twenty-foot. Wollaston, who 

 knew this, has given in his Catalogue only 1st and 4th, 

 &c. classes of the first 1000, the second not having been 

 published at that time, and they are without the yearly 

 variation. 



Bode has given the first and second Catalogues complete, 

 and calculated the yearly variation to each by de Lambre's 

 Tables. (See Bode's preface, p. iv., line 18.) The last 

 500 were not published yet in 1800, or rather 1801. I 

 only mention this that if you wanted the variations, and 

 had a mind to trust to that catalogue of errors, it would 

 save an immense trouble by copying them. But the more 

 I think of these, the more I doubt if it would not be in- 

 juring the places of objects merely (though accurately) 

 pointed out, to calculate them in the same manner as stars 

 repeatedly observed in fixed instruments ; and I doubt if 

 your father noticed Bode's having done so. 



You will find undoubtedly many more nebulae which may 

 have been overlooked for want of time, frying clouds, hazi- 

 ness, &c., especially in those sweeps which are registered 

 half sweep. It is a pity time could not be found for making, 

 as was often intended, a register in which the boundaries of 

 the sweeps, with the nebulae, were all brought to one time, 

 either to Flanisteed's or 1790 or 1800. The register in 

 Flamsteed's time, which is from 45" to 129, is for that 

 reason the best mem. At the time that register was made, 

 the apparatus for sweeping in the zenith was not completed, 

 and higher than 45 was not used. 



If you should wish in the latter part of the summers 

 (when your father was generally from home) to fill up the 

 unswept part of the heavens, you might perhaps discover as 

 many objects as would produce a pretty numerous catalogue. 

 You will see in the register of Flamsteed's time a curved 



