161 
“Observations on the Alteration of the Freezing Point 
in Thermometers,” by Dr. J. P. J oule, F.B.S., Y.P. 
Having had in my possession, and in frequent use, for 
nearly a quarter of a century, two thermometers, of which I 
have from time to time taken the freezing points, I think 
the results may offer some interest to the Society. Both 
thermometers are graduated on the stem, and are, I believe, 
the first in this country which were accurately calibrated. 
Thirteen divisions of one of them correspond to one degree 
Fahrenheit. It was made by Mr. Dancer, in the winter of 
1843-44. My first observation of its freezing point was 
made in April, 1844. Calling this zero, my successive 
observations have given 
0 April, 1844. 
5 '5 February, 1846. 
6-6 January, 1848. 
6-9 April, 1848. 
8- 8 February, 1853. 
9- 5 April, 1856. 
11 T December, 1860. 
11-8 March, 1867. 
The total rise has been, therefore, '91 of a degree Fahrenheit. 
The other thermometer is not so sensitive, having less than 
four divisions to the degree. The total rise of its freezing 
point has been only *6 of a degree ; but this is probably 
owing to the time which elapsed between its construction 
and the first observation being rather greater than in the 
case of the other thermometer. The rise of the two thermo- 
meters has been almost identical during the last nineteen 
years. 
