( 400 ) 
the time (measurements of 8 till 10 altitudes near the prime vertical) 
and a comparison of the so found local time with that of Greenwich, 
as given by the chronometers on board several ships that touched 
at this port. The English Admiralty-chart (corrected up to 1897) 
gives also 13°8' for the Eastern longitude of Ambriz. 
As provisional value of the latitude I assumed 7° 50’ south. 
The observations were made before the old factory cf the „Nieuwe 
Afrikaansche Handelsvennootschap” and consist of the three fol- 
lowing series: 
1. Circummeridian altitudes of the sun on May 10, 1893. 
For the reduction of the observations I used the following formula: 
cos p cos 2 sin 
sin (Ò 2) gnl” sind — Pp) 
dees 
- represents the northern zenith distance, whereas southern latitude 
is regarded negative. The term depending on 2 sim°}¢ could be 
neglected, as its influence, even in the case of the greatest hour 
angles, was too small. 
The following corrections, and daily rates of the chronometer 
were found: 
March 18 1893 —- 46m 56s 50 
— 0s24 
April 12 » + 46 50.40 
— 0.28 
May 3 „ + 46 45.48 
— 0.39 
June 3 wv + 46 33.26 
That I might use a constant value for the declination of the sun, 
the hour-angles were reckoned from the instant of the maximum 
altitude, computed from the formula: 
do ; 
ty = 0.255 DE (tangp — tango) 
in which t,, the hour-angle of the maximum altitude, is expressed 
d dod Wes 
in seconds of time and =e stands for the variation of the sun’s 
( 
declination in one hour, expressed in seconds of are. 
The observed altitudes were corrected for refraction, parallax and 
semidiameter. The places of the sun etc. were taken from the Con- 
naissance des Temps. 
