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VIII. Demonstrations of the late Dr. Maskelyne's formula for 
finding the longitude and latitude of a celestial object from its 
right ascension and declination ; and for finding its right ascen- 
sion and declination from its longitude and latitude, the obli- 
quity of the ecliptic being given in both cases. By the Rev. 
Abram Robertson, D.D. F.R.S. Savilian Professor of 
Astronomy in the University of Oxford, and Radcliffian Ob- 
server. Communicated by the Right Honourable Sir Joseph 
Banks, Bart. G.C.B. P.R.S. 
Read February 15, 181b. 
The methods given by our late Astronomer Royal, for solving 
the two problems alluded to, were printed in his introduction 
to Taylor's Logarithmic Tables. Since their appearance 
before the public, they have met with the warmest approba- 
tion from those most capable of judging of their merit; but 
no one, so far as I know, has fully demonstrated them ; nor 
has any one, so far as my knowledge extends, observed two 
mistakes with which they are accompanied, and which in cer- 
tain cases would affect the accuracy of their application. 
These circumstances, and a consideration of the high cha- 
racter of the author of the formulae, induced me to reduce the 
following demonstrations and remarks into the form of a 
short memoir. I trust I shall not be charged with any im- 
proper motive for thus noticing the mistakes. Candour, I 
