514 ACCOUNT OP ASTRONOMICAL OBSERVATIONS 



ers. The present paper, therefore, can only claim the 

 advantage of recording good observations, taken in 

 great numbers, and computed with scrupulous atten- 

 tion: and perhaps of affording some data to astronomers 

 in other climates, for further investigation into the ef- 

 fects of refraction. 



4. Although the method for correcting zenith 

 distances at any given time, for abbreviation, nutation, 

 and solar equation, is well known to astronomers, yet 

 I do not omit giving a general statement of the man- 

 ner in which I have applied these various corrections 

 to my observations. Such as belong to Regulus are 

 given in Table I. and may serve as an example for the 

 rest. For the detail of each respective rule I must re- 

 fer the reader to books of astronomy, for I have no- 

 thing new to offer on the principles upon which they 

 are grounded. 



5. I HAVE however to observe, that refractions beino- 

 one of the subjects under consideration, I have com- 

 puted it separately for every star, accordmg to Dr. 

 Bradley's theory, in which the state of the atmos- 

 phere at the time of observation is considered, and 

 without any reference to the tables. The rule may be 

 found demonstrated in Vfnce's Complete System of 

 Astronomy^ Chap. VIII. page 82, and following. I 

 'ave reduced it, for a more convenient arrangement, 

 in cthe following form : 



n 



Corrected Refraction K=: Tanirt'z^r y re / .Ta 400. 



A f 350° 



The following example will shew the notation. 

 Example. 



The mean observed zenith distance o( Regulus by ob- 

 servation is O'' of 14".326 - Z. 



