Investigations into tlie conditions governing the temperature of tlie body. 47 



similar in appearance to mine recorded above and to the curves of 

 other night-watches. The level of the curve is lower than usual for 

 him (see curve 4 on fig. 7 and curve 2 on fig. 6), and there is a 

 'well-marked fall in the "night". The rise at 3 a.m. is due to a 

 walk of observation on land; owing to the construction of the curve 

 this rise becomes much more extensive than is justly due to it; but 

 the low temperature before and after sufficiently clearly mark the 

 fall of temperature. 



Thus, there are valid reasons why a "reversed" curve of tem- 

 perature has not hitherto been obtained; certain demands must 

 necessarily be met first, demands not consistent with social life in 

 civilised countries. 



These demands may however be met on a high-arctic expedition 

 during the polar night, which in a case like this is to be preferred 

 to the "perpetual" day in summer. The sun occasions a continual 

 unrest; the working hours are unlimited and a little food emanci- 

 pates one from the regular meals. It will therefore be very difficult 

 to make all adopt the same mode of life, and even if only one 

 breaks away from the order the consequence easily becomes more 

 or less irregularity all along the line. Apart from this the difference 

 in the intensity of light is much more appreciable in summer than 

 in winter, just as the variations in the day and night temperature 

 are much greater. During the polar night the case is different. All 

 lamps are put out at certain fixed hours, appointed by the leader 

 of the expedition; then it is night; during the remaining hours the 

 lamps are lit and we have day. As practically all work is done 

 indoors, the dining hours are kept by every one. And in the open 

 air the light by day. and at night does not vary appreciably and the 

 changes in the temperature are comparatively small. 



The experiment was made on the "Danmark Expedition", whilst 

 in the harbour at 76° 46' N. L. in January 1907, and by general con- 

 sent and obligingness, both from the leader of the expedition and 

 the other members, the transition was made very quickly and 

 easily. Bed-time was delayed once 4 hours and then 8 hours by 

 inserting an extra meal. Then the "reversal" was accomplished. 

 The lamp was lit and put out at the same time as before; one met 

 at the table at the same time as usual. Only on clear days one 

 might miss at "noon" a little brightness in the southern sky, other- 

 wise the change was betrayed by no external sign. It was a fact 

 of which we -were conscious; but in the great majority even this 

 knowledge was not able to produce the feeling of anything unusual. 

 Time rolled along on its even, ordinary way. More than half of 

 the 28 members of the expedition felt, indeed, just as usual as soon 



