on Atmospherical Refraction, &c. igg 
of the polar distances, divided by the difference of the sum of 
the refractions, quotes ,0284485 ; which being increased by 
unity, is the factor to be multiplied into the assumed refrac- 
tion, viz. 36A'. Then the mean refraction at 45 0 will be 56,^5 
x 1,02845 = 58, ''10734: the co-latitude 
77° 3 7 53/o.9 0 8 + 94.9377 x ,02845 __ 3 s» 3^ 57 ps 97 
2 
and the latitude = 51 28 2,103, 
which will be found the same, from the mean of the corrected 
co-latitudes in the tenth column, as given by the above thirty- 
four stars. 
I have made these deductions from the fixed stars only ; 
and therefore it will be required to compare the result with 
the sun at the solstices. I have preferred the former, from 
the greater number of observations to be so obtained, as well 
as from the more accurate bisection of a star, than the appli- 
cation of a wire to the limb of the sun ; I have, however, en- 
deavoured to render the observations of the sun, of equal con- 
sequence, by means of two fixed, and one moveable wire ; 
the latter measures a space to one of the fixed wires, distant 
2 g 45/74 from the other, the sum of which is the diameter ; 
the sun passing at the same time through the centre of the 
field. These wires are applied to the upper and lower limbs 
of the sun, by direct vision, the eye glass having a vertical, as 
well as a horizontal motion. The centre of the sun is found, 
knowing the distance of the extreme fixed wires, from that 
in the centre of the field ; but the refraction must be applied 
for each limb, the difference of refraction at the winter sol- 
stice being 8" ; therefore this diminution of the diameter must 
be noticed. The few opportunities I have had to observe the 
