336 
scale for one degree of the thermometer was found by him to be 
“0001237, and of one foot of Ramsden’s bar ‘0000740 of an inch; 
consequently, the excess of the expansion of 40 inches of the 
scale, above 40 inches of the bar, for each degree above 54° will 
be -0001657 of an inch; and this quantity has been used in 
computing the corrections for temperature. 
The comparison of both scales with the bar was made at the 
same time ; but to avoid confusion, I have given the results in 
separate tables. The scales and the 40-inch bar were Jaid to- 
gether two days previously to commencing the examination. 
TaBce I. 
Comparisons of the Distance from Zero to 40 Inches of General 
Roy’s Scale with the 40-inch Bar. 
Difference be- 
tween the scale| Correction for 
and the bar in | Temperature. 
Roy. | inches. 
An Account of the Comparison of 
Roy’s scale 
shorter than 
the 40-inch’ 
Readings. 
— 000407 
— 000385 
— ‘000086 
+ :000043 
+ -COO171 
+ 000043 
+ 000086 
+ 000522 
—- 
—*000829 
— ‘001326 
—°001825 
—°001856 
—°001873 
—'001873 
— 001773 
—°002220 
Mean 
*001813 
*001701 
‘001829 
00-1698 
By the above comparisons, General Roy’s slale appears to be 
shorter than the 40-inch bar ‘001698; to which adding *000034, 
the quantity by which Ramsden’s bar exceeds the 40-inch bar, 
we have *0017382 of an inch for the difference in defect between 
General Roy’s scale and the standard used in the Trigonometrical 
Survey, with which it was supposed to be identical. 
Taste II. 
Comparisons of the Distance from Zero to 40 Inches of Sir 
GzorGE SuucksurGn’s Scale with the 40-inch Bar. 
Ditterence be- 
huckburgh’s 
Readings. tween the scale |Correction for} scale shorter 
Date. | Temp. =: and the bar in |Temperature | than the 40- 
, Bar. | Shuck.| inches. bar. 
May 7| 59°0 23 W5-2 —'002234 —'000829 "003063 
9) 65°0 41°5 62 —'000877 — 001823 ‘002 700 
65°2 41 58 —'000728 —°001856 002584 
653 30 49 —'000813 —°001873 002686 
65°3 30 5t — 000899 —'001873 002772 
647 27 50 — 000954 — 001778 002757 
10} 67°4 36°2 | 41°5 —'000227 —"002220 002447 
67°8 33 44 —'000471 —002287 °002758 
12) 67°5 42 48 —°000257 —*002237 002494 
Mean *002696 
