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ROYAL SOCIETY OF CANADA 



thermometer could be placed at any distance in the water down to a 

 depth of about five feet. It could also be bent so as to pass under the bord- 

 age ice, and thus somewhat protected from the direct rays of the sun. 

 On February 26th the readings were made at night under similar con- 

 ditions. 



The following readings on February 13th and 1 5th were obtained : 



Had the stem of the thermometer been painted black, no doubt it 

 would have indicated a higher temperature. On the bottom, in the quiet 

 water, the lower temperature suggests the presence of a layer of ground ice, 

 made very probably by the clear nights previous. The rapidity with which 

 the temperature approached the freezing point on February 15th, when 

 the sky became clouded over, also indicates this. The observation given 

 of the temperature of the back water, with the sun clouded over, was 

 made about one hour after the previous set of readings. 



On February 26th a successful set of night readings was obtained, 

 which will illustrate to a moderate extent the effect of a clear, cold atmos- 

 phere. The maximum and minimum tempeiatui-es for that date are re- 

 corded as -|- 9° F. — 4° F., with a temperatuie during the night of about 

 0° F., and towards morning of a little above. The sky was not so clear as 

 could be desii-ed during the earlier part of the night, but towards mid- 

 night it became very clear and remained so for the greater part of the 

 night. Eeadings were started at 4.30 in the afternoon of February 26th 

 and were continued at intervals of every two hours until 7 o'clock the 

 following morning. 



The freezing-point mixture had to be repaired and renewed at inter- 

 vals all night, to ensure sufficient uniformity. The measurements com- 

 menced by showing the water to be slightly above freezing, owing to the 

 influence of a bright sun all day. Towards evening it became colder and 



