180 EFFECT ON SNOW THERMOMETERS. \_May~, 



At noon today the thermometers placed in the snow- 

 bank on the 3rd were withdrawn : that at the floe sur- 

 face in contact with the ice indicated -f-14; the other, 

 having three feet snow beneath and one foot above, 

 = -f- 2 : both rose immediately 2. The external ther- 

 mometer was 18 at the same moment. These thermo- 

 meters therefore represent the minima gauges ; the ex- 

 ternal indicating, during this ten-day interval, on the three 

 consecutive days, the low temperatures of 19, 15, 

 10; the ice therefore, protected by a covering of 

 snow three feet in depth, was warmer by 19 -f- 14 

 = 33 ; and one foot, probably the thickness of a rapidly 

 constructed snow-house, would afford by this experiment 

 -J-19 -+- 2, or 21 warmer than the external air, and 

 free from the searching power of the breeze, which, after 

 all, is the most important consideration in such calcu- 

 lations. The thermometers were of deep tints of ruby 

 when first embarked ; but long exposure to light had so 

 much affected one, that it now presented a pale amber 

 hue. These were now exposed on a brown spar, to test 

 the sun's direct rays : the amber rose to 17, the ruby to 

 18. Further exposure on the black sides of the ship 

 afforded amber 40, ruby 42. They were then at this 

 mark replaced in the snow. 



May 14. Our temperatures during the last ten days 

 afford max. +1S, niin. 19, mean +2'529: not much 

 warmth to boast of. Having noticed several indications 

 of more determined tidal influence, experiments were 

 tried today by inserting a tide-pole through the fire-hole 

 (a hole about six feet square, abreast the gangway, kept 

 open for obtaining salt water in case of fire). This in- 



