( 289 ) 
For San Salvador the 3 corrected values (l.c. p. (406) 9) become : 
Sun ERO ah LN 
. 10.0 
a Crucis 14.0 
Mean value — 6° 15' 12” 
Thus the mean result for San Salvador changes 4” and seems at 
the same time more reliable than before. 
IV. Preliminary determination cf the longitude of Chiloango. 
To determine the Jongitude of Chiloango I applied the method 
recommended by Katser!) for use in the Dutch Indies as it has 
been developed with regard to the reduction of the observations by 
Prof. J. A.C. OUDEMANS”), who himself has reduced in this way the 
observations of Messrs DE LANGE for determining the longitude of 
Batavia ®). 
I commenced my observations on January 22d of this year and 
since that date i have obtained on 9 nights 19 observations of equal 
altitudes of the moon and a star. All these times however I observed 
the first limb of the moon, as with the limited time I had at my disposal 
observations after the full moon did not yet succeed. But I hope to 
continue my work and then to be able to obtain also observations 
of the second limb. 
In the first 7 observations, made in January, the times of transit 
were observed over the 2 horizontal threads; after the reticule had 
been turned 90°, the 7 horizontal threads were used. Therefore the 
first observations will be less accurate. All the observations were 
made with the telescope to the right, as a reversal of the instrument 
was of no use here. Care was always taken to keep the deviations of 
the level bubble as small as possible; the difference between the 
readings for the corresponding observations of the moon and the star 
was always less than one division, and generally much less. 
') F. Karser. De sterrekundige plaatsbepaling in den Indischen Archipel enz. 
Amsterdam 1851. 
2) J. A. ©. Ouprmans. Over de bepaling der geografische lengte door de waar- 
neming van gelijke hoogten der maan en eener ster. (Versl. en Med, Akad. Amst. 
6e deel, pag. 25. Amsterdam 1857). 
3) J. A. C. Oupemans. Verslag van den geographischen dienst in Nederlandsch-Indié 
van Januari 1858 tot en met April 1859. Batavia 1860. 
