192 
PROCEEDINGS OF SECTION A. 
( 0 ) Bombay -Madras. — Observers : Captains Campbell and Heavi- 
side. Station at Bombay tbe same as that used for the interval 
That at Madras was 65 feet due north of the transit circle of the 
Madras Government Observatory. This interval, though not deter- 
mined directly, is certainly as well ascertained as any other — (11), 
Part I. 
Its value is deduced from the telegraphic measurement of the 
difference of longitude of nine Indian arcs joining the six stations — 
Bombay, Bolarum, Bellary, Mangalore, Yizagapatam, Madras ; the 
most direct route being Bombay-Bellary-Madras. (See diagram 
in (11) Part I., page 16.) The operations were executed by these 
officers in 1875-76-77 through the land lines, using the same 
instruments as mentioned in (#,,). Time signals were exchanged 
automatically, and simultaneously recorded at the two stations. Every 
possible precaution was taken to guard against error, systematic or 
accidental, and the work generally was carried out with a completeness 
that leaves nothing to be desired. The result for this interval is 
shown in (11) Preface to, Part I. ; page (xviii.). 
We are now enabled to deduce tbe longitude of Madras ; but 
before doing so I shall mention and consider another set of totally 
independent operations, which must be regarded as a powerful check 
upon all others hitherto discussed — viz., the determination of the 
longitude of Madras, via Ispahan- Kurraeliee. Indeed, if it were not 
for the very limited and somewhat incomplete observations at 
Kurrachee, and the undetermined personal equation of the observers 
at Ispahan and Madras, this chain would be entitled to much greater 
weight than the one via Suez- A den -Bombay* because it connects 
Madras with Greenwich in four steps including only five stations, three 
of which are fixed national observatories, in addition to having the 
interval Kurrachee-Madras measured twice independently. I regret 
that, with the exception of the operations at Madras and Kurrachee, 
the details of the observations are not at band ; the results given here 
being taken from General Addison’s paper — (10) page 83, and (13) 
pages 47, 54, 81. The actually measured intervals are as follow : — 
( p ) Berlin -Ispahan. — Observers: The astronomers of the Berlin 
Observatory, at Berlin ; and Dr. Fritsch, chief of German Transit of 
Venus Expedition in Persia (1874), at Ispahan. The operations were 
repeated on eight nights— viz., November 16, 17, 18, 19, 20, 21, 23, 
and 27. 
( q ) Ispahan -Kurrachee. — Observers : Dr. Fritsch at Ispahan, and 
General T. Addison, C.B., at Kurrachee. General Addison observed 
for time with a portable transit instrument, and recorded his 
observations as well as galvanic signals by chronograph, Signals were 
exchanged on December 11 and 12, 1874. Personal equation between 
the observers not determined— (10) page S3. 
(r) Kurrach ee-Ma dras. — General Addison at Kurrachee, and 
Mr. Norman Pogson, Government Astronomer, at Madras. Galvanic 
signals were exchanged ou one night only — viz., December 13. The 
time at Kurrachee depends on the observation of three stars. Results 
given by General Addison — (10) page 83. 
(r t ) Kurrachee- Madras. — Same operations as in (r); value deduced 
by Mr. Pogson — (13) pages 47, 54, 81. 
