G58 



REPORT 1884 



inches, and in No. 2, - 390 inches ; the graduation in both being to tenths of a 

 degree. They -were tested by immersing them in a wooden vessel filled with snow 

 and water, placed in a room in which the temperature varied from 34° to 37°. By 

 the means of several trials the corrections for the melting point of ice were found 

 to be, for No. 1, 0-87° and for No. 2, 0-83°. No. 2 was found broken February 17, 

 1671, which brought the experiments to an end. Thirteen years afterwards No. 1 

 was tested again in a similar manner, and the correction was found to be 1-02°, the 

 change being 0-15°. One of these thermometers was placed hi the hole in the 

 block of ice, and the other in the water in which it floated, and to eliminate errors 

 from imperfect corrections they were interchanged from time to time. 



The results of these experiments are given in the following table. To vary 

 the conditions, the hole in the block of ice was filled with different substances as 

 stated in the table. It was supposed that the substance that would enable the 

 temperature of the ice to be ascertained with the greatest precision was benzine. 

 The mean of the two results in this condition when thermometer No. 1 was in the 

 interior of the ice, and No. 2 in the water in which the ice floated, gave the tem- 

 perature of the interior of the ice 0-188° below that of the water in which it floated ; 

 and the mean of the two trials, when No. 2 was in the ice and No. 1 in the water, 

 gave the temperature of the interior of the ice, 0-266° below that of the water in 

 which the ice floated. The mean of the four trials in which benzine was used 

 giving the temperature of the interior of the ice was 0-227° below that of the water 

 in which it floated. 



The mean of the two results in which air occupied the interior of the ice, the 

 thermometers being interchanged, gave the temperature of the ice 0-073° below 

 that of the water in which it floated. 



In the single result in which the hole was filled with water, the readings gave 

 the temperature of the interior 0-017° below that of the water in which the ice 

 floated. 



The mean result of all the trials gives the temperature of the interior of the 

 block of ice 0-153° below that of the water in which it floated; the irregularities 

 in the results of the several trials are however too great to permit the adoption of 

 this mean as the exact difference. Every trial, however, gave a less difference 

 than was found by Forbes, and I think it is safe to say that as a result of these 

 experiments, the temperature of the interior of a block of fresh water ice floating 

 in fresh water, the temperature of the air being between 30-5° and 46-6° Fahrenheit, 

 is about one-fifth of a degree below thirty-two degrees, or the melting point of ice. 



During the above experiments, the block of ice became reduced by thawing from 

 its original diameter of seventeen inches to about fourteen inches. 



