Survey of Northeast Greenland. 225 
Control of measurement by means of computation of the side d 
of the triangle [V—IX—O. 
Bere: 41°53'53” load Na 39596 
ро. 19125.28 — cosec a'.. 0.08589 
BER, 34 3025 — sin d’.... 9.99114 
Ga 67 0134 logd... 3.42299 (control!) 
NE 78 2801 
At the station pointing from the more remote cairns V, VIII and 
X the angle V- O— VIII was measured at 44°30’05’” and angle V—O—X 
1054737". 
The side lengths computed are given in the table below. From 
the computation appeared 2 O— VIII — X == 22°49'06” and Z O—VIII—V 
— 10 10/28 
The levellings of the triangulation points. 
In the measurement of the horizontal angles I had endeavoured 
to attain as great an accuracy as possible in the given circumstances. 
My object — to establish a connection with the network of the 
Germaniaexpedition, the most northerly points of which on Shannon 
Island and Muschelberg lay more than 150 kilometres in a straight 
line from Danmarks Havn — demanded the greatest possible accuracy, 
if the connection was to be of such vital importance to the deter- 
mination of longitude at Danmarks Havn as I aimed at. 
For the determination of the altitudes of mountains, an extreme 
accuracy in the measurement was of no importance, as our lack of 
knowledge of the conditions of refraction would always make the 
results attained rather uncertain. As mentioned above it was, how- 
ever, for quite different reasons necessary to measure the vertical 
angles twice. In this manner the accuracy of the measurement of 
the vertical angles became disproportionately great, and did not 
correspond to the other circumstances. 
The altitude of the telescope above the foot of the cairn was 
measured at an estimate with a measuring tape, and so also the foot 
of the cairn itself was nearly always pointed in the course of the 
levelling. But the “foot of the cairn” was a rather vague conception, 
which should have referred to the brass bolt in the interior of the 
cairn, but which came to mean the lower edge of the lowest circle 
of stones in the cairn, which might, at the same cairn, vary some- 
what in its altitude above the level of the sea. It was of great im- 
portance that it often turned out to be difficult to point the “foot of 
the cairn”. This was nearly always the case, when we did not have 
the sky as a background, as well as in a few cases where the cairn 
15* 
