334 
MR. H. J. CHANEY’S RE-DETERMINATION OF 
Table I. — Density of Water. 
Logarithms of Ratios of the Maximum Density of Water to its Density at t. 
t. 
Log. W t- 
Diff. 
t. 
Log. W t- 
Diff. 
4° 0. 
o-ooooooo 
17° C. 
0-0005098 
5 
36 
36 
18 
5867 
769 
6 
136 
100 
19 
6682 
815 
7 
299 
163 
20 
7544 
862 
8 
524 
225 
21 
8451 
907 
9 
808 
284 
22 
9401 
950 
10 
1152 
344 
23 
10393 
992 
11 
1553 
401 
24 
11426 
1033 . 
12 
2011 
458 
25 
12498 
1072 
13 
2523 
512 
26 
13609 
1111 
14 
3090 
567 
27 
14757 
1148 
15 
3708 
618 
28 
15941 
1184 
16 
4378 
670 
29 
17158 
1217 
17 
0-0005098 
720 
30 
0-0018409 
1251 
Condition of the Water. —The water was twice distilled in pure tin and glass stills, 
and was found to be free from any impurities likely to affect the weighings. It was 
deprived of air by boiling, and no correction for the absorption of air was therefore 
made. It was, however, found that at the temperature of 62° Fahr. (B. = 30 inches) 
a cubic foot of distilled water, freed from air, weighed about 321 grains more than 
when nearly “ saturated ” with air. 
Standards of Length and Comparators. 
Standards of length and Comparators. —For the purpose of measuring the external 
dimensions of the gavimeters in inches of the present imperial yard, four 9-inch end 
standards of length were used ; as well as a steel 6-inch and a steel 3-inch standard 
(1884). At 62° Fahr., the true mean length of the four 9-inch standards was 
8‘99975 inches ± O'OOOOl inch; the 6-inch and 3-inch standards having a true 
length of 6‘00020 and 2 - 99975 inches respectively. For intervals between O'l and 
O'Ol inch there was also used a subdivided inch “ D,” the accuracy of the subdivisions 
of which had been measured by the Standards Commission in 1868 to dz 0'000005 
inch. 
For the comparison of the dimensions of the gravimeters with the standards 
of length, there were used two comparators of well-known forms; one a Whitworth 
contact comparator, the other a micrometer-microscope comparator designed by Mr. 
J. Simms. By means of the former comparator measurements by touch might be 
made to O’OOOl inch ; and optically to 0 , 000025 inch, by means of the microscopes. 
