296 I. P. Косн. 
When the drawing is finished, one marks off with figures the 
points at which one desires to make observations. 
On PI. VI are reproduced two of the sketches drawn by HAGEN 
in 1906 and belonging to the Station К Ш on the top of Rekvedgen 
in Skærfjorden. 
Bearings and levellings. 
In the course of the chapter on triangulation, stress has been 
laid upon the fact that one ought not to mix up the measuring of 
horizontal and vertical angles, because the accuracy of the measuring 
of horizontal angles would suffer by it. Considerations of that kind 
are of no value in the geographical sketching survey. One ought, 
as mentioned above, to take the greatest possible care in the deter- 
mination of the position of the observation stations; but in return 
one may, as a rule, permit oneself certain facilities as regards the 
sketching survey, without running the risk of the map becoming in 
that way less accurate. I am thinking of the following facilities: 
Each single angle is only measured once. 
The horizontal and vertical angles are measured simultaneously, 
in which manner one observation at each point is saved. 
The reading is made in whole minutes and only takes place 
on the one vernier. 
The level is not read. This last measure, however, does not 
exempt one from keeping an eye on the level. On the con- 
trary. If the bubble of a well-verified level shifts so much 
from the middle of the tube that the level correction would 
amount to more than a minute, the levelling screws must be 
re-adjusted. 
By making use of the above-mentioned simplifications a good 
deal of time is saved, which may be of great importance, when one 
is tired or when the weather conditions are unfavourable, but it will 
appear that one has at the same time dispensed with control as 
regards errors of reading. It is, therefore, necessary to concentrate 
one’s attention on this point. 
When at the measuring of vertical angles one does not reverse 
the telescope but contents oneself with one pointing, the zenith point 
correction must be known, and as the latter, in consequence of the 
rough handling on sledge trips, may have altered on the journey 
from one camping site to another, it must be determined on each 
separate occasion. 
In order to make sure that the position of the instrument has 
not altered in any perceptible degree during the observation one 
must, to conclude, once more sight the first point observed. 
