68 



Mr. F. D. Brown's Notes on Thermometry. 



Reading of Standard when wholly immersed =393-42. 

 f Barometric pressure, corrected and reduced, =7601. 

 ( Corresponding temperature of steam =100°*00. 



Number of 

 divisions sur- 

 rounded by 

 cold water 

 and occupied 

 by mercury. 



Temperature 

 of water. 



Eeading of 



Standard, 



T. 



Value of C 

 = 393-42 -T. 



Value of m, 

 



(T-*)N" 



317 

 277-5 

 221 

 173 

 130 

 79 



o 

 130 

 123 

 120 

 121 

 121 

 12-1 



389-01 

 389-54 

 39030 

 39094 

 391-58 

 392-30 



441 



3-88 

 312 

 2-48 

 1-84 

 1-12 



•0001599 

 •0001594 

 •0001604 

 •0001631 

 •0001610 

 •0001612 



An inspection of the above table is sufficient to convince us 

 that the value of m is constant, and equal to the apparent ex- 

 pansion of mercury in the glass of which the thermometer was 

 made ; the numbers would probably have agreed even more 

 closely, were it not that it is impossible to arrange the appa- 

 ratus so that the cold portion of the thermometer-stem follows 

 directly upon the hot portion. There must always be an 

 interval occupied by the cork, the temperature of which 

 is uncertain. It should be remarked that there is no indication 

 whatever of the value of m increasing when that of N increases. 



Precisely the same results were obtained with the second 

 standard thermometer, as is shown by the following table: — 



Reading of Standard BS, when wholly immersed, =419'21. 

 f Barometric pressure, corrected and reduced, = 7605. 

 \ Corresponding temperature of steam = 100 o, 02. 



Number of 

 divisions sur- 

 rounded by 

 cold water 

 and occupied 

 by mercury. 



Temperature 

 of water. 



Reading of 



Standard BS, 



=T. 



Value of C, 

 =419^21-T. 



Value of m, 

 C 



(T-*)N" 



302 

 237 

 174 

 127 



120 



11-9 

 120 

 120 



415-13 

 415-96 

 41684 

 417-47 



4-08 

 3-25 

 2-37 

 1-74 



•0001535 

 •0001556 

 •0001548 

 •0001557 



Here, again, the value of m varies only within the limits of 





