ij2 Gen. Roy’s Account of 
Feet. In. Pts. 
And confequently there remains for the 
length - - - - 28532 ♦ 7.92 
But when the chain was adjufted in Mr. 
Ramsden’s fhop, as above-mentioned, the tem- 
perature was 55 0 . Being then carried into St. 
James’s Church-yard, its length was laid off on 
brafs pins inferted into the Hone coping of the 
church-yard wall, for the purpofe of compan- 
ion on any future occafion, at which time the 
temperature had changed to 55°!. After the 
raeafurement in Romney Marfh had beenfinifhed, 
the chain in the temperature of 39% being 
ftretched out on the wall, its length was found 
to fall (hort of the original points on the brafs 
pins T W-o °f an inch. Now, 55°.5 — 39 0 = 1 6°. 5, 
and 1 6°.5 x 0.00763 — 0.126 in.; hence 0.126 
— T y^=io.o23 in. is the fpace which the chain 
had only lengthened during an operation which 
continued above fix weeks ; and one-half of this 
fpace, W&.0.0115 multiplied by 285.37 chains 
13 = 3.282 in., the correction to be added to the 
apparent length for the wear of the chain during 
the operation - 4*0. 3.282 
Whence the length becomes - 28532 • 1 1*202 
Laftly, the bafe is to be Ihortened for its 
height of 15I feet above the mean level of the 
fea, fuppofed to be 6 feet 8 inches above low- 
water ipring tides at High Nook, which gives 
for the reduction - - - — o. 0.166 
And 
