OBSERVATIONS FOR LATITUDE. 
141 
Latitude. Ther. 34°. Bar. 30 inches. Index error + 3' 10". Observer 
south of the star. 
o 
r 
// 
Alt. of in Quicksilver.. 
59 
42 
Index error. 
3 
10 
2)91 
2 
52 
45 
3 1 
26 
Refraction—Ther. 34°, Bar. jo .. 
00 
59*5 
True Alt. 
30 
26-5 
90 
00 
00 
Zenith Distance. 
29 
3V5 
s. 
Declination. 
48 
19*6 
s. 
Latitude. 
.. .. 45 
17 
sr 1 
s. 
When the meridian altitudes of a star above and below the Pole can be 
observed, half the sum of the corrected altitudes gives the latitude at 
once, without any computation. When the Pole Star can be observed, 
the latitude is very easily found by the rule and tables given in the 
( Nautical Almanac 9 ; and as a fairly correct approximation without any 
calculation at all, the corrected altitude of the Pole Star is the latitude, 
if the star is observed when ft and f, or still better, when /3 and <? Ursx 
Minoris appear to the eye to be in a line parallel with the horizon; a 
method which, as a rough observation, has the advantage of being 
independent of watch, tables, or ‘ Nautical Almanac/ 
Circum-meridian observations } or observations near the Meridian. 
A latitude by meridian altitude depends only on one altitude, the 
highest observed, and as this is liable to error, being only one observation, 
a more accurate result can be obtained by taking sets of altitudes on either , 
or both sides of the meridian , and noting the time corresponding to each 
altitude by a watch whose error on apparent time at place is known. These 
altitudes are taken in the manner previously described, and the observa¬ 
tions should be commenced at about a quarter of an hour * before the 
heavenly body observed comes to the meridian, and may be continued until 
* Very good results may be obtained from observations with a star half an 
hour or more from the meridian, if the local time be accurately known. 
