98 I. P. Koch. 
During the summer of 1907 when I began some experiments, 
the object of which was to appraise the astronomical refraction, my 
attention was attracted towards the importance of the special refraction 
of the meridian aperture, and since then the temperature of the 
Observatory was measured by means of the dry thermometer in an 
Asmann aspiration psychrometer, which I borrowed from the expedition 
meteorologist. An apparatus of this kind is, however, not strictly 
necessary; if sufficiently careful one may make shift with an ordinary 
thermometer without an aspirator. 
As an ephemeris and star catalogue we used the full edition of 
the Nautical Almanac. Experience showed, however, that it would 
have been well, had we supplied ourselves with a larger star catalogue. 
Electric light. It appears from the above that small electric 
lamps were practically indispensable for the purpose of the winter 
work in the Observatory. These small lamps were, however, also 
used at the daily meteorological readings, for the observations to 
determine the conductivity and potential drop of the air, at the 
measuring of the Gnipa Cave and on several other occasions. Finally 
they were used to advantage on the sledge trips undertaken during 
the autumn and winter so as to get sufficient light for astronomical 
observations in the open air. 
As far as is known there are no publications from former arctic 
expeditions treating of the use of electric light, and the material had 
consequently to be prepared at home on the basis of a rather rough 
estimate of the influence of the low temperature. 
The electric light was based on the use of dry cells from the 
manufactory of Hellesens Enke & V. Ludvigsen, Copenhagen. Ten 
dry cells, type 0 Nr.0, were calculated for use in the permanent 
lighting up of the Observatory, but besides we carried thirty-nine 
small cells, type 0 Nr. 7, of which the eighteen were collected in six 
small battery boxes in sets of three. The incandescent lamps were 
quite small carbon filament lamps, requiring a tension of about 
4!/2 volts and a current from 1» to 1 ampère. 
The electric light, which turned out to be so extremely valuable, 
was, on the other hand, the cause of many disappointments, because 
it failed so frequently. The cause of this has to this day never been 
explained fully. 
The intensity of the light was often considerably diminished to- 
wards the end of a protracted series of observations, but was set 
right again, when battery and lamp were left for some time in a 
warm room. We were inclined to think that the diminution was 
mainly due to the cold, but unfortunately we could not investigate, 
