68 ASTRONOMICAL anv” 
True meridian altitude of 8, e “gre organ 
True meridian altitude of ‘the pole-ftar, 40 32 9 
Sum of the declinations and altitudes, 179 59 59 
Hence it appears, that the fum ofall the errors in the affum- 
ed declinations. of thefe two ftars, in the refraction, quadrant, 
and mean altitudes, do not amount to more than one fecond, 
Tt may therefore be prefumed that the quadrant, obfervations, 
-and elements of the calculdtions are very exact. The reafon 
‘why the obfervations on B in Aquarius were chofen to examine 
‘the quadrant by, was becaufe they are nearer the mean latitude 
than thofe of any other ftar, and therefore may be prefumed to 
be the moft correct, 
II. Obfervations of the variation and dip of the magnetic 
needle, at the Univerfity in Cambridge, ic 
> Time. = Variation. Dip. |  Obferver- 
Year. Mon. BD ga ET HM OR ey | | 
4198/7 wo sb? ewe oe s Blade; s 
1742, 13 oW Dr. Winthorp. o8 
1757, i uLs a0 WI Dr. Winthorp. 
$761, Feb. 25, ob rra WE | Mr. Williams. | 
1763, nme 7 OW} ~~ |Dr. Winthorp. 
1780, Dec. 25, 1, P. M. MI, 2 W169 -51 | Mr. Williams. 
1782, June 21, 4, P. M. | 6 46W|69 41 | Mz. Williams. 
1783, Dec. 23 3 P ME le 6 52 W|69 41 | Mr. Williams. 
^in the year 1782, Profeflor Sewall obferved the diurnal va- 
riation of the magnetic needle during feyeral months. At 
the - 
