( 454 ) 
vey of South-Sumatra, were begun at the station Langeiland P68. 
These measurements were carried from the West Coast of Java over 
the Strait of Sunda and are lately completed at the station B' Gadang 
P39, situated in the Government of the West Coast of Sumatra. 
The triangulation consists of one continuous chain of triangles, 
which, beginning at the side Langeiland ? 68 — Gs Radja Basa P 67, 
is connected with the side Gs Talang P38 — Bt Gadang P 39 of 
the triangulation of the West Coast of Sumatra. 
It is true that this side does not exceed the length of 17120 meters, 
but a connection with the longer side Bt Poenggoeng Parang P45 — 
Gs Talang P38 had to be abandoned after it was found that the pillar, 
erected at Bt Poenggoeng Parang during the triangulation of the West 
Coast, was so damaged that it no longer could be used for this purpose. 
The experience made during the measurements of the base at 
Padang for the triangulation of the West Coast of Sumatra, executed 
by means of a 20 meters steel tape, did not tempt us to measure 
also the base line for South Sumatra with this comparatively unreli- 
able apparatus; and as an instrument admitting of a high degree of 
accuracy was not available, no special base was measured, but the 
length of the first side of the chain was based upon the two sides 
Batoe Hideung P 15 — Gs Karang P35 and Gs Karang P35 — 
x3 Gede P36 of the Java triangulation. For the Java triangulation 
3 base lines had been measured with an apparatus of RersoLp, which 
had been sent back to Europe in 1882. 
For the orientation of the South-Sumatra chain, determinations of 
latitude and azimuth were made at the station Gf Dempoe P 71 in 
the Lampong Districts in 1897. The geographical longitudes were 
reckoned from the meridian of 3°15’ West of Batavia. This meridian, 
which nearly passes over the middle of South-Sumatra, is deter- 
mined by the geographical longitude of the Java station Gs Karang 
P35, as given in Abtheilung V der Triangulation von Java, p. 207. 
To obtain a zero mark for the determinations of altitude, tidal obser- 
vations were made during a year at Telok Betong in 1897 and 1898. 
From these the mean height of the sea level in Lampong Bay, the 
Lampong-zero, was derived. This was transferred to the pillar 71559 
at Telok Betong by levelling, and thence by reciprocal but not 
simultaneous zenith distances measurements to the primary point 
Gs Betoeng P 70°). 
1) In 1902 and 1903 tidal observations were also made at Benkoelen and from 
them the Benkoelen-zero (the mean height of the sea level at that place) was 
derived, which wili be used afterwards, when the secondary measurements will 
be so far advanced. 
