192 Bond, Graham, and Peirce, on the Latitude of Cambridge. 
of the telescope makes a small angle a, with the prime vertical, so 
that the zenith is at Z’, instead of Z; and if Dh denotes the hour 
angle of P Z, while LZ, denotes the latitude; L, may be obtained 
from L by the solution of the right triangle Z PZ’, or by the formula 
L, = L— (35 Dh) sin. 1” sin. 2 L. 
The value of Dh may be determined from the transits of low 
stars, and is the difference between the times of transit of one of 
these stars over the true prime vertical and over the axis of colli- 
mation of the telescope. ‘This value, as also that of a and of L 
— L,, is computed in Table IX. The value of a is derived from 
the formula 
a = 15 Dh sin. L. 
The places of the stars were not taken from any of the published 
tables, but from all the observations which have been published 
at Greenwich, Edinburgh, and Cambridge, within the last ten 
years. The declinations are given in Table II, for the purpose of 
future revision. The values of Z given by the different stars, 
with the means, are contained in Tables VIII. and X. 
After this memoir was presented to the Academy, a note was re- 
ceived, through the kind attentions of Captain Beaufort, R. N., from 
the astronomer royal, Mr. Airy, in which he has liberally commu- 
nicated the results of all the Greenwich observations upon the 
stars here observed, to the end of the year 1844. These obser- 
vations induce me to increase the declinations, given in Table IL., 
of a Lyre, by 0.10; of y' Andromede, by —0”.01; of uw Urse 
Majoris, by — 0”.14; and of 8 Canum Venaticorum, by 0”.18. 
These corrections are incorporated into the results of Table X. 
