60 



French tables have been used in the above. Had Bradley's 

 refractions been used, the parallax would have come out 

 considerably greater. The value of p is less exact, on ac- 

 count of the smallness of its co-efficients. 



A mean of 20 observations near six o'clock in the evening, 



gives mean zenith distance = 4o°.0'. 30",64 — ,\p. 



The mean of the above 76 = 4fl.O. 30,80 — ,01^?.* 



* M. Delambre in his remarks on M. Piazzi's observations, proposes to examine the 

 effects of the parallaxes in changing the right ascensions. This confirmation would be 

 very satisfactory, and might be readily attained, were some stars so much affected 

 by parallax as M. Piazzi has supposed. But if the parallaxes be so small as my 

 observations tend to point out, no expectation of this kind could be entertained as to 

 « Lyrae, Arcturus, and a, Cygni. 



As to y Aquilae, the right ascensions in March and September would differ by about 

 — of a second of time, and, under the circumstances of the case, it would require 

 attention to detect this quantity, but it might b*e done. If this difference exist it ought 

 to be allowed for in computing the apparent from the mean right asceasion. 



