YALUE OF AUSTKALIAN LONGITUDES. 
193 
(V„) Kurracliee- Madras . — This interval was determined indirectly 
through Bombay and Bellary and other Indian arcs by Captains 
Campbell and Heaviside in their usual excellent manner, as already 
spoken of. The operations were executed in 1880-81. 
(s) Difference of longitude between General Addison’s and 
Captain Campbell’s station. The position of the former was 0*6 sec. 
east of the station “ used in the Great Trigonometrical Survey at that 
place” — (10) page 84. The position of the latter is described in (11) 
Part I., page 252, as being G1 feet north, and 152 feet=l"*65= 
0T1 sec. west of the “ Telegraph Office Station,” which is a point “ on 
the eastern terrace of the upper story of the block of dwelling quarters 
standing in the angle between Macleod road and Telegraph road, 
marked by a circle and dot engraved on the floor of the terrace, and 
connected with the Hill Stations A and Mutrani of the G.T.S.” It 
seems, therefore, that the “Telegraph Office Station” is the one 
referred to by General Addison as being 0*0 sec. west of his 
observatory. 
We may now compare the three values (r), (r,), (r„) of the 
interval Kurrachee-Madras, reducing them all to the Telegraph 
Office Station of the Great Trigonometrical Survey. 
see. 
h. 
m. 
Bee. 
(r) 
+ 0*60 
= 0 
53 
06*82 
( r i) 
+ 0*60 
= 0 
53 
06*45 
(r,J 
-0*11 
= 0 
52 
55*61 
The two values (r) and (r x ) are derived from the same few and simple 
observations of a single night. Their difference is 0-37 sec., and has 
not been accounted for by the astronomers concerned. The value 
(r„) is 11*21 sec. smaller than (r), and 10*84 sec. smaller than (rj. 
This large error was pointed out in (6), page 31* No doubt some 
clerical mistake occurred somewhere, or the position of General 
Addison’s station may be misunderstood ; but to assume that this is 
a clerical error of ten seconds so as to make it a round number, as 
Mr. Pogson proposes — (13) page 81 — seems arbitrary. It is strange 
that in all these years we have never heard an explanation of this 
matter. 
The longitude of Madras is thus arrived at by two routes, as 
follows : — 
Via Suez- Aden- Bombay. 
h. 
in. 
sec. sec. 
Longitude of Aden (Gill) 
2 
59 
55-772 + 0-113 
Aden-Bombay (w x ) 
i 
51 
19-973 + 0-05(5 
Bombay-Madras (o) 
0 
29 
43-530 + 0-058 
Longitude of Madras, VI. ... 5 
Via Ispahan- Kurracliee. 
20 
59'275 + 0-139 
( o) 
0 
53 
34*865 
(p) 
2 
33 
05*44 
(?) 
1 
01 
13*09 
HW + Oh)} 
0 
53 
06035 
Longitude of Madras.,. 
5 20 59*430 
IM 
VII. 
