Variation of the Sun's Rigid Ascension and Declination. 443 



Note. — In whatever manner M. Burkhardt combined the ob- 

 servations of Lacaille, Mayer, Bradley, Le-Gcntil, Maskelyne, 

 Piazzi and his own, he could never obtain more than 48", for the 

 Secular Variation of the Obliquity, he has concluded the Secular 

 Diminution cannot be greater than 50', he has never believed, 

 that it amouiijd to 52''; — Lagrange states the Diminution at 

 56'' per cent>'v; Laplace, and Delambre in liis Solar Tables, 

 52"*1. In the 2d edition of Vince's Astronomj', from a mean cf 

 the observations of Dr. Maskelyne and several other astrono- 

 raers, it is stated at 50'; whereas Dr. Brinkley makes it 43' 

 only. Fide Phil. Mag. vol. 56, p. 213. 



Norfolk-street, Lynn Regis, J. UttiNG. 



June 4, 1821. 



To the Editor of the PhVosophicul ISlagazine. 



Lynn, June 5, 1821. 



Dear Sir, — I have sent you a supplementary Ta'-le*, con- 

 taining the Variation of the Sun's Right Ascension and Declina- 

 tion for 100 seconds Diminution of the Obliquity of the Ecliptic, 

 in preference " to a Diminution of 60", after the example of 

 Mayer," as suggested by your CorrespondeiU in the Philosophical 

 Magazine for last month (p. SDa of this volume) : for, in finding 

 the proportional parts of obliquities dift'ering from that assumed 

 in the construction of the Tallies, the operation of dividing by the 

 first term is unnecessary, and is in my Tables dispensed with : 

 attention only is required in pointing off the decimal places. 

 The error in the Table of the Variation of the Sun's Right Ascen- 

 sion in time cannot, at its maximum, exceed about one-tenth of 

 a second in a century: any further correction is therefore uii- 

 Jiecessary. 



Such persons as choose to have the Tables copied for their use 

 can easily substitute the latter variations as the Diminution of the 

 Obliquity, for the Secular Variation originally inserted in the 

 Tables. 



I remain, yours truly, 



J. Utting. 



• The Tables alluded to, is that occupying the four pages immedl-at«ly 

 preceding this letter.— Edit. 



3 K 2 LXXXIH. On 



