776 PROF. W. H. MILLER ON THE CONSTRUCTION OF THE NEW STANDARD POUND. 
thermometer by ice is said to be less accurate than when snow is used. In the pre- 
sent instance it appears from the following comparisons to have been sufficiently 
exact. In February 1844 the freezing-point of a thermometer G, having an arbitrary 
scale, was 37*4. In March 1845 it was 37'5, the thermometer having been im- 
mersed in snow in both cases. In May 1855, the bulbs of G and K being almost 
in contact with each other and surrounded with broken ice, the reading of G was 
37*55, while that of K was 0°‘00. In July 1855, the reading of G, when immersed in 
pounded ice, was again found to be 37*55. In March 1855, by a mean of ten com- 
parisons, the reading of G was 48'541, when that of K was 2°^365. By a mean of ten 
other comparisons, the corresponding readings of G and K were 90°*797 and 11°'432 
respectively. Hence, one part of G=0°’2145. If we suppose the zero of G unchanged 
since 1845, the freezing-point of K would be — 0°‘004. But if we suppose the zero 
of G to have been correctly determined by immersion in ice in May and July 1855, 
or that the zero had ascended 0*05 part =0°'011 since 1845, the freezing-point of K 
would be -l-0°'007. 
Assuming the freezing-point of K in 1855 to be 0°'00, as given by observation, the 
corrections of K will be, — 
t. 
t-K. 
t. 
#-K. 
t. 
if-K. 
o 
0 
0-000 
35 
-0-020 
O 
70 
-0-040 
5 
-0-003 
40 
— 0-023 
75 
— 0-043 
10 
-0-006 
45 
— 0-026 
80 
-0-046 
15 
— 0-009 
50 
— 0-029 
85 
— 0-048 
20 
— 0-011 
55 
— 0-031 
90 
— 0-051 
25 
— 0-014 
60 
— 0-034 
95 
— 0-054 
30 
-0-017 
65 
— 0-037 
100 
-0-057 
The thermometers B, C, D were made by the late M. Bunten of Paris. They are 
all divided into centesimal degrees by lines etched upon the tubes. The graduation 
of B extends from —23° up to -1-107°. It bears the inscription ‘25 Mai 1843. 
Divise le 18 Mai 1844.’ The graduation of C extends from —24° up to -f41°. It 
is dated 1841. The graduation of D, which is also dated 1841, extends from —25° 
up to -|-53°. 
The graduation of B was examined at certain points of the scale by the method 
described by Professor Forbes in the Transactions of the Royal Society for 1836, 
p. 578; and the boiling- and freezing-points determined, in order that the other ther- 
mometers might be referred to it as a standard. It was not, however, used as a 
standard, in consequence of the acquisition of the Kew thermometer, which has a 
scale of much larger dimensions, and is more accurately and closely divided, and 
also on account of the inconvenience in using it as a standard, arising from the large 
amount of the displacement of its zero. Immediately after boiling, February 1, 1845, 
the freezing-point of B was — 0°'20; on February 4 it was — 0°T5 ; on March 3 it 
was — 0°T 1 ; in December 1846 it was 0°‘00 ; and in July 1855 it was -|-0°T1. The 
depression of the zero, which in the present case amounts to 0°'31 C., depends upon 
