[barn es] 



NOTES ON FRAZIL AND ANCHOR ICE 



19 



c. , ^, 



nearly in length those of light. Finally, however, all the heat waves 

 will become absorbed, and this point probably represents the limit of dis- 

 integration of anchor ice by the sun. It represents also the limit of 

 formation for the converse eli'ect of heat radiation /rom the bottom, which 

 is precisely similar. 



Taking the results obtained on Feb. 13th, 1897, and reproduced here 

 for the sake of convenience, it will be noticed that there are in all only 

 three observations, at three different depths. These will be sufiEicient to 

 obtain a general idea of the rate of absoi'ption. 



Unfortunately the observation at live feet was made with the ther- 

 mometer bulb on the bottom, and as the presence of ice was evident 

 there, it indicated a lower temperature than it otherwise would have 

 done. Then, again, the thermometer bulb, being of a light gray lead 

 colour, would not absorb the full amount of the thermal rays. It was 

 also continuously losing heat to the surrounding water, the temperature 

 indicated being really nearly the temperature of the water produced by 

 the thermal absorption. Such of the rays as were not absorbed by the 

 water would not, therefore, be wholly detected. It is possible to form 

 some idea of the very large effect produced by the sun's heat by assum- 

 ing, as seems justitiod from a plot of the observations, some form of expo- 

 nential formula to connect the depth with the temperature indicated. 

 Taking the expression 



- ^ (t-t,) 

 ■S= Ae 

 which fits the obseiwations most closely, where 



S = depth of immersion of thermometer bulb. 



t = temperature indicated by thermometer, 



fj = temperature of water if uneffected by sun's rays. 



K&A — constants,' 

 there is given in common logs. 



log. S = log. A — K (t—t,) -434 



