394 Major-General' Roy’s Account of the 
imagined, not- having been entirely finifhed before the fir ft 
week of ] uly. We fhall therefore leave it going on, and in 
the mean time proceed to deferibe the inftruments that were 
fubfequently made ufe of in the. firft and fecond meafure- 
ments. 
K 
'0‘f 
Steel' Chain. Tab. XVII. 
One of the firft inftruments, which that able artift Mi:;. 
Ramsden had orders to prepare, was- a fteel chain, one hun- 
dred feet in length, the heft that he could make. Not that it? 
was intended, , nor could it be fuppofed, that we fhould abfo- 
lutely abide by the refult that this- chain fhould furnifh us 
/ 
l/: 
fj,* /"A 
with, for the length of the bafe ; but it' was hoped, that an 
inftrument of this fort might be made, which would meafurc 
diftances much more- accurately than any thing of that kind 
had ever- dbne before and it was con fide red as an object of 
fome confequence, to endeavour to ftmphfy, and render as eafy 
as poffible, the meafurement of bafes in future : an operation 
which,, hitherto, has always- been found to be tedious and 
troublfefome, to which we may now further add, uncertain 
likewife, when done with rods of deal-, as, will appear from the 
account hereafter to-be given. 
The con ft ruction of the chain, which is on the principles of 
that of a- watch, will be underftood from the reprefentation of 
fome of its chief parts, to the full fixe, in tab. XVII.: where 
the firft, or zero-end link, is fhewn both in plain and elevation, 
in the ftate in which it was originally- applied to mealurement 
on the furface of the ground; Each link confifts of three 
principal parts-; namely, a long plate ; two fhort ones, half 
the thicknefs of the former, with circular holes near the 
^ extremities.. 
