The Account of a 
Aug. 7th, in the evening. Coffers covered with the linen cloth. 
Thermometers. 
Mean. 
Micr. 
Divisi*. 
Total contr. 
Inches. 
Contr. 
on 1 0 . 
Inches. 
1 
2 
3 
4 
5 
90 
80 
67 
60,75 
91 
80 
68 
62,75 
89 
81,5 
69>5 
62 
9 i 
81,5 
69 
6 2 
92 
81 
% 
62 
90,6 
80.8 
68,5 
61.8 
*9 
* 3>5 
*3 
,073077 
.090385 
,050000 
CO *oco 
GO 
t''* In. .t''* 
OOO 
OOO 
The mean result from these nine experiments is 0,007492, 
or 0,0075 inch to i° of Fahrenheit, on 100 feet of blistered 
steel ; which differs only toMoo^ P arts of an inch from Ge- 
neral Roy's conclusion with the pyrometer ; but the number 
,0075 is preferred in these measurements, as being deduced 
from experiments made with the chain itself. 
art. iv. Particulars relative to the Commencement of the Ope - 
ration, &c. 
After the chains were compared, and the rate of expansion 
determined, as related in the preceding article, several trials 
were made of arranging the pickets and coffers in such a man- 
ner aS might be supposed proper for the reception of the chain. 
It was soon found, however, that this method of measuring 
would be neither so expeditious or accurate, as if the coffers 
were placed upon tressels, such as were made use of by Ge- 
neral Roy in his measurement with the glass rods. An ap- 
plication was therefore made to Sir Joseph Banks, who very 
