Survey of Northeast Greenland. 93 
of the necessary shifting when the position of the telescope was 
altered. | 
The best manner of guarding against the effects of the rays of 
the sun was by letting the instrument stand uncovered in the direct 
rays about an hour before the observation, and in such a manner 
that both ends of the frame of the level were illumined. Then im- 
mediately before the observation the shade was attached and the 
instrument verified. If we had not taken care that both ends of the 
level frame were illumined, the contraction, when the shade was 
attached, varied at the ends, and the instrument then got out of 
order shortly after the verification. 
The instrument, when not in use, was covered with an oil-cloth 
bag, which was dropped over it. The telescope was then always. 
adjusted in such a manner that the object glass pointed towards the 
zenith. During a snowstorm in October 1906 the Observatory was 
partly filled with snow, which penetrated everywhere through the 
fine crannies of the joints. On the top of the instrument was a snow 
column of about !/2 metre high, and the weight of this, which chiefly 
weighed on the telescope itself, lifted the opposite end of the hori- 
zontal axis of rotation out of position. In order to prevent a repe- 
tition, an oil-cloth bag, about 1.5 metres long with the bottom up- 
wards, was hung from the roof of the Observatory so as to enclose 
the instrument. 
The greatest difficulties were due to the low temperature"). To 
make astronomical observations in a temperature of — 20° to — 30° 
(Centigrade) is of course not a pleasant experience, but the low 
temperature only plays a minor part as regards the well-being of the 
observer, partly on account of the comparatively small amount of 
moisture in the air, and partly because one soon learns to protect 
oneself from the cold by means of suitable clothing, and by covering 
those parts of the instrument which one cannot avoid touching — 
screws, ocular frames etc. — with chamois leather, ebonite and 
such like. 
The low temperature, however, affects the instrument in a most 
troublesome manner, and only with the utmost care can we protect 
ourselves against the effects. 
In consequence of the moisture of the exhaled air and of the 
skin the instrument becomes covered with rime. This cannot be 
avoided altogether, and one must always have a bit of chamois 
1) The lowest temperature recorded during an observation from the permanent 
Observatory is 29° (Centigrade). On sledge trips as low a temperature as 35° 
has been recorded. 
