288 I. P. Koch. 
The difference found above of 50’ in the azimuth would thus 
arise by an error of 0'4 on the zenith distance. Such an error on 
the zenith distance, measured by a single pair of observations is, it 
is true, rather great, though not greater than that it must arise 
rather frequently (cf. for instance second pair of observations in noon 
latitude, 6/V 1907, pp. 265—267). 
Determination of Longitude during the Sledge Trips to Kap Bridgman 
in 1907 and to Dronning Louise’s Land in May 1908. 
In the course of the preparation of the maps it appeared that 
nearly all of the observation stations in Skerfjorden and Dove Bugt 
might be connected with the triangulation stations proper, either 
through a complete trigonometric station pointing or through a 
favourable azimuth at a previously determined station, in connection 
with a determination of latitude. As far as these stations were con- 
cerned, there was thus no occasion to have recourse to the more 
uncertain determination of the longitude by means of the watch. 
During the two above-mentioned sledge trips a connection with 
the triangulation stations was, however, not possible. The deter- 
mination of the longitude by transport of the watch came to play a 
considerable part during these sledge trips, and there may conse- 
quently be every reason to look somewhat more closely at the results 
obtained in this manner. 
The sledge trip to Kap Bridgman in 1907. 
In March 1907 I had determined the correction and rate of the 
below-mentioned watches to be used on the sledge trip. 
The 26/III 1907, forenoon. 
и Е ЕЯ Я 
Watch Clock time Correction to Rate in twenty-four 
| Given to 
Danmarks Havn | hours of the clock | 
K 88000008 ++ 10m328,5 + 1056 | Koch 
57203 710 40 +59 28.7 + 3m51.3 | Косн 
57508 | 8 04 00 + 6 00.2 — 2.4 G. TosTRUP 
57332 8 04 00 + 6 17.4 — 4.4 | HAGEN 
Watch K was an ordinary, good pocket watch, which was to be 
used as an observation watch. The three other watches were Carrusel 
pocket chronometers from Bonniksen, Coventry. Watch 57203 was 
regulated to sidereal time, which was of course impracticable on a 
spring journey; it had, however, to be taken along in order to re- 
place a mean time chronometer, the glass of which was broken. 
Besides the above mentioned four watches a fifth good pocket 
