394 Major-General Roy's Account of the 



imagined, not having been entirely finillied before the firft. 

 week of July. VVe fhall therefore leave it going mi, and in 

 the mean time proceed to defcrlbe the inftruments that were 

 fubfequently made ufe of in the firfl and fecond meafare- 

 nients. 



Steel Chain. Tab. XVII. 



One of the firfl: inftruments, which that able artift Mr^ 

 Ramsden had orders to prepare, was a fteel chain, one hun- 

 dred feet in length, the befl: 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 furniili us^ 

 with, for the length of the bafe ; but it was hoped, that an 

 inftrument of tliis fort might be made, which would meafure 

 diftances much more accurately than any thing of that kind 

 had ever done before: and it was confidered as an object of 

 fome canfequence, to endeavour to iimplify, and render aseafy 

 as poffible, the meafurement of bafes in future ; an operation 

 which, hitherto, has always been found to be tedious and 

 troublefome, to which we may now further add, uncertain 

 iikewife, when done with rods of deal, as will appear from the 

 account hereafter to be given. 



The conftru£lion 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 fize, in tab. XVII. where 

 the firfl:, or zero-end link, is fliewn both in plan and elevation, 

 in the ftate in which it was originally applied to meafurement 

 on the fur face oi the ground. Each link coniifts of three 

 principal parts-; namely, a long plate ; two fliort ones, half 

 the thicknefs of the former, with circular holes near the 

 5 extremities 



