196 
PROCEEDINGS OE SECTION A. 
good enough for the purpose, and also as a check to our work. 
Captain Helb shortly after sent all his observations in detail over 
to Melbourne, where they were found in every respect excellent. 
The two values (w) and offer a partly independent value of 
the interval Port Darwin to Singapore, although the Banjoewangie 
longitude itself remains affected by the unknown personal equation 
of II. D. and B. The difference between the direct value (u) and the 
indirect one ( w ) -f ( w t ) is as follows, viz. : — 
li. m. sec. sec. 
O) 0 42 0678 ± 0*076 
(«0 1 05 50*84 ± 0-091 
1 47 57-62 
Personal equation (D.B) 02 
Singapore to Port Darwin 
(indirect) ... 1 47 57*60 ± 0*119 
Singapore to Port Darwin 
(direct) (u) ... 1 17 57*48 ± 0*046 
These combined in terms of their mean errors give — 
Singapore (Captain Darwin’s station) — 
h. m. sec. sec. 
Port Darwin 1 47 57*49 ± 0*045 ... VIII. 
The longitude of Port Darwin may now be deduced, viz. : — 
h. m. sec. sec. 
Longitude of Madras (VI.) 5 20 59*275 ± 0*139 
Madras to Singapore (£„) 1 34 24*07 ± 0*040 
(v) 1*51 ± 
Singapore to Port Darwin (VIII.) 1 47 57*49 ± 0 045 
Longitude of Port Darwin (IX.) 8 43 22*34 ± 0T52 
(w) Port Darwin to Adelaide. — Observers : Mr. (now Sir Charles) 
Todd at Adelaide, and myself at Port Darwin. The observations at 
Adelaide were made with the transit instrument of the observatory. 
The exchange of galvanic signals here consisted in sending clock-beats 
to each other automatically (generally two sets of two minutes each), 
which were simultaneously recorded on the chronographs at the two 
stations, the chronograph of the receiving station recording at the 
same time the beats of its own clock. The personal equation between 
the observers was determined on several occasions through Mr. E. I. 
White, then Chief Assistant at the Melbourne Observatory, and 
directly in Melbourne. The operations were repeated on six nights — 
viz., February 14, 15, 22, 23, and 26, and March 2, 1S83 — (6) page 22. 
(;/) Melbourne- Adelaide . — The operations for this interval were 
carried out at the two observatories under the direction of their 
respective Government Astronomers, Mr. Ellery and Mr. Todd. The 
observations were made by the latter at Adelaide, and by Mr. E. J. 
White at Melbourne. Clock-beats (generally two sets of two minutes 
each) were exchanged, and simultaneously recorded on the chrono- 
graph of both stations, &c., as in the case of the interval (#), Port 
Darwin to Adelaide. Personal equation between Messrs. Todd and 
White was determined several times. Comparisons made on five 
nights — viz., February 15, 17, 23, 26, and March 2 (1883). 
^ Difference 0*12 sec. 
