39'6 Major-General Roy’s Account of the 
firft mode of application it was foon difcovered, as we flialt 
have occafon to mention hereafter, how admirably the chain 
performed ; and that, with fome farther precautions, a hill 
greater degree of exafhiels might be attained, by fupporting it 
on Rands, or even on planks, laid on, or but little removed 
from, the common furface of the earth. For this purpofe, 
the two end-links were altered, each being now made equal to 
one foot, exclulive of the handles. By referring to tab. 
XVII. the nature of this alteration will be ealily conceived. It 
confifted in fcrewing to the under fide of the handles, very 
near the joints, two feather- edged pieces of brafs * ; the one 
denoting zero, and the other ioo feet. Over the dart at the 
■'firft, a plummet with a fine River wire being fufpended, that 
wire, by a very dm pie apparatus, hereafter to be defcribed, 
may be brought accurately to coincide with any point whatever 
of commencement : and at the fecond, a line line with a 
knife, or other fharp inftrument, being drawn on a piece of 
card placed there for the purpofe, and changed as often as 
needful ; or, as was like wile pradtifed, and found to anlwer 
better, a line on a moveable Hide of brafs, attached to the top 
of the Rand or plank, being brought to coincide with the fea^ 
ther-edge, and then faRened underneath ; the extremity of the 
ioo feet is readily afcertained : and thus the meafurement 
may be continued on with great accuracy to any diRance at 
pleafure. 
That the chain, in this its altered Rate, may Rill be advan- 
tageoufly applied to ordinary meafurement on the furface of 
the earth, the pieces above defcribed, having Ready pins, and 
being faRened with fcrews, can be eafily removed, and others, 
* They were originally of brafs, but are now of fteel , that the edges by being 
harder might run lefs rife of being damaged. 
>-r 
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exaflly 
