386 Mr. Herapath on True Temperature, and the [Nov» 



At \Q± hours, a.m. temp, room 67f°. 



Mercury, left glass, 67 ; right glass, 67 

 Water 66± ; 66; 



At 1 hour, p. m. temp, room, 69-1. 



Mercury, left glass, 68-g- ; right glass, 68|- 

 Water 68 ; 67 £ 



At 8± hours, p.m. room, 65 T \°. 



Mercury, right glass, 66-^- ; left glass, 66-^ 

 Water 66ft ; 66 



The next morning at six o'clock, the room was at 65 T 8 7 . 



Mercury, left glass, 66 ; right glass, 66 

 Water 6d T %; ; 65 T V 



At9 a.m. the room was at 62£°. 



Mercurv, left glass, 62f; right glass, 62£ 

 Water 6l£; 61f 



Between the two last observations, the window had been put 

 open to try whether the damp air, owing to a little rain which 

 was falling, would have any effect. A current of air had also 

 sometimes been allowed to pass through the room by setting the 

 cloor open, but I could not perceive it produced any considerable 

 effect on either glass in particular. Generally, as the experi- 

 ments indicate, the temperature of the right hand glass of water 

 was less than that of the other, though the left hand glass was 

 to wards the window. This I attribute in part to the excess of 

 superficial exposure which the water had in the left hand glass; 

 the exposed superficies being nearly in the ratio of 3 to 2. The 

 depth, however, of the water in the left hand glass was only 



12 



about -t^f °f that m the other. In the glasses with mercury, 



1 3**1 



the differences of the temperatures were, except in one or two 

 instances, so trifling, that I could not appreciate them. Nor 

 could I discover any inequality of temperature in the top, 

 bottom, sides, or middle, of the same glass, though I took great 

 ■care to detect it. It should likewise be mentioned, that in mak- 

 ing my observations, I noted the temperature of the atmosphere 

 before I removed the thermometer from the book ; and to avoid 

 being obliged to wipe or touch the ball of the thermometer, I 

 immediately afterwards took the temperature of the glasses of 

 mercury, deferring to take that of the water until the last, that 

 no error might arise from the influence of aqueous particles 

 adhering to the bulb of the thermometer. In the subsequent 

 table, I have brought the results together, and computed the 

 arithmetical means. 



