276 I. P. Koch. 
When the declination of the sun becomes negative, the sun is 
practically inapplicable in determinations 'of time on sledge trips, 
because one must make the observation at too great a distance from 
the prime vertical. In order to attain the greatest possible accuracy 
one must thus use fixed stars or planets. The lighting of reticule, 
circles and level, by means of artificial light is, however, a most 
disagreeable thing on sledge trips in a low temperature. The small 
electric lamps are apt to fail, so that one has to have recourse to 
lanterns, and it has frequently occurred that I have been reduced to 
using an unprotected candle in the open air. 
In order to avoid the inconvenience of the artificial light one 
ought to make use of the twilight. The reticule will then be visible 
without artificial light, nor will it during the lightest part of the 
twilight be necessary to light up the circles. 
We have often to great advantage been able to observe Venus 
in the twilight. The following is an example of an observation of 
this kind: 
Pustervig, 26/III 1908. Afternoon. Determination of 
time by Venus. Observer: WEGENER; Assistant: LINDHARD. b = 
743 mm; t = + 17.6; ф = 76°55'10”; 1 division of the level = 22”; 
sidereal chronometer No. 57203, correction towards Grw. + 2h51m415, 
Telescope left Telescope r Er 
57203 |— === | — 57203 — 
A IR) Ge Obj. | | A | B 
Il mk il 2 = = 
7h16m00s | 289055 3 55'.4 | ‚| 11.8 | 5.0 | 78180058 | 70°12.2 12.0 | 5.0 | 11.8 
20 03 | 42.2 | 42.3 | 12.3 | 5.6 21 56 | 25.3 | 248 | 48 | 113 
23 59 | 29.0 | 28.8 | 12.2 | 5.5 25 56 | 39.0 | 38.9 | 4.2 | 11.0 
| | | | | | 
Уегшег | Level | | „Ver nier Må Level 
| 
Obs. Obj. 
| | | 
The observations are grouped in three pairs. 
Mean $ = + 1h27m235 with a mean error of a couple of seconds 
(about 200 metres). 
When in the autumn of 1907 ihe meteorological station was 
established in the inner part of Dove Bugt at Pustervig, it became 
necessary to determine the position of the station with the greatest 
possible accuracy. The requisite determination of latitude by Polaris is 
mentioned оп рр. 271—272. The longitude had to be determined by 
means of a chronometric voyage — sledge trip — between Danmarks 
Havn and Pustervig. At Pustervig the clock correction was determined 
by zenith distance observations at two fixed stars. The observations at 
Pustervig were performed under circumstances which were the most 
