various British Standards of linear Measure. 287 
Readings of the sixth Mean readings of all] Value of the sixth 
interval. | the intervals. interval + or —. 
37°0 36°5 —0'5 
40:0 37°8 —2°2 
40-0 39°6 —0:4 
83:0 &3-0 —0-0 
87:0 86:1 —0:9 
83°5 84:4 +0:9 
—0°5 
Mean 
The sixth interval, therefore, is too short 0-5 of a division. 
This interval was now compared with the forty-inch bar, the 
thermometers being at 57°; the microscopes were transferred 
from one bar to the other alternately. 
Readings of the sixth|Readings of the forty- 
interval. inch bar. 
From this it appears, that the forty-inch bar is shorter than 
the sixth interval 0-3 of a division; and as the sixth interval 
was found to be shorter than the mean of all the intervals 0:5 of 
a division, the result of the whole is, that the forty-inch bar is 
shorter than one-sixth of Ramsden’s bar 0:8 of a division, or 
000034 of an inch. 
I may here remark, that the differences observable between 
the results of the various comparisons of the intervals of Rams- 
den’s bar, may be attributed to the large size and imperfect state 
of most of the dots ; those bounding the sixth interval are for- 
tunately the least injured. 
Having 
