« 
LITERATURE. 
Brepig u. Wernmayr. Zeitschr. f. physik. Chem. Vol. 42. 1903, p. 601. 
Herine. Pflüger's Archiv. Vol. 161. 1915, p. 544. 
Saxar. Zeitschr. f. Biologie. N. F. Vol. 46. 1914, p. 505. 
Mines. Journal of Physiology. Vol. XLVI. 1913, p. 188. 
Lussana. Arch. di Fisiol. Vol. VI. 1909, p. 478. 
May 1916. Physiological Laboratory of the 
University of Groningen. 
Astronomy. — “Contributions towards the determination of 
geographical positions on the West coast of Africa” IV. By 
C. SANDERS. (Communicated by Prof. E. F. van DE SANDE 
BAKHUYZEN). 
(Communicated in the meeting of June 24, 1916). 
1. Introduction. 
My last paper') on my determinations of geographical positions 
on the West coast of Africa dates from 1908; I describe there what 
I did in that direction in the years 1903—1906. In 1906 I was in 
Europe for some time, but in May 1907 I had returned to Chiloango, 
while in the mean time my stock of instruments had been augmented 
by a Zuiss telescope of 80 mm. aperture and 120 em. focal distance. 
The principal purpose for which I had obtained this telescope 
was to be able to observe occultations of stars by the moon, in 
order in this way to improve my results for the absolute longitude 
of Chiloango, which | had previously determined by means of lunar 
altitudes. At the same time I wished to try to make other observations, 
which might be of use scientifically, my especial aim being the 
observations of eclipses and other phenomena of the satellites of 
Jupiter; while, when the telescope had only been in my possession 
for a short time, l had an opportunity of observing the transit of 
Mercury on .Noy. 14'» 1907, at least partially. I published the result 
of these observations in 19087). At the same time, some of the 
observations, especially those of the reappearance in occultations, 
were made very difficult by the circumstance that my telescope had 
provisionally been provided with an azimuthal mounting, which was 
to be replaced later by a parallactic one. This proved, however, to 
be difficult to accomplish and finally I ordered a second telescope 
exactly the same as the first, but mounted parallactically. 
1) G. SANpeRs. Bijdragen tot de astronomische plaatsbepaling op de Westkust 
van Afrika. (Ll). Versl. Akad. Amst. 17, 66—84. 1908. (Proceedings XI. p. 88). 
2) C. Sanpers. Waarneming van den overgang van Mercurius ......... 
Versl. Akad. Amst. 17, 84—85. 1908. (Proceedings XI. p. 108). 
Proceedings Royal Acad. Amsterdam. Vol. XIX. 
