260 I. P. Косн. 
The base line b is measured by pacing or with the measuring tape. 
The most difficult feature of the survey and that which involves 
the greatest loss of time is the finding of a suitable point of direction 
and getting the latter in the direction of the sight; this difficulty, 
however, partly disappears, according as one becomes trained in the 
use of the instrument. It is of the greatest importance to select a 
remote point of direction. In this manner the error committed 
through not being quite accurately adjusted in the line between the 
first station and the point of direction is diminished. 
The circumstance that the instrument may be used for the 
Fig. 37. Dog sledge with hodometer. 
pegging out of a right angle may, by the way, come in useful during 
surveys. | 
The hodometer is a wheel, the revolutions of which are auto- 
matically indicated on a register. 
Our hodometers were bicycle wheels without rubber tyres. The 
circumference was two metres. The wheel was put in a fork placed 
behind the sledge. 
As a cartographical instrument the hodometer was of no great 
assistance, the sledging being too uneven for that. In pack-ice where 
one had to wriggle a good deal, the hodometer, of course, indicated 
a distance which was far too great for cartographical purposes, 
whereas on glare ice it often indicated too small a distance. On an 
even, hard snow plane it was, however, rather reliable. 
