Meafurement of a Bufe on Hon n flow- Heath.- ^9 5 



extremities of each ; and two caft-fleel pins, or axes, fuited to 

 the diameters of the holes, which ferve to conned the adjoin- 

 ing hnks together. The holes in the fhort plates are made 

 rough or jagged with a file; fo that when they have embraced 

 the ends of two adjoining long ones, and tlie pins have palled 

 th rough all the holes, in rivetting their extremities, they are 

 made perfectly fart, and as it were united to the fhort plates; 

 while the embraced ends of the long ones turn freely round 

 on the middle part of the pins. 



At every tenth link the joint, juft now defcribed, has a 

 pofition at right-angles to the former ; that is to fay, the Ihort 

 plates lie here horizontally, and the pins paffing through 

 them fland vertically. Thus, there being in the whole chain 

 two hundred caft-fteel pins, one hundred and eigiity lie hori- 

 zontally ; and twenty, including the tw^o by which the han- 

 dles are attached, ftand vertically. Thefe crofs-joints, which 

 were chiefly intended that the chain might fold up in a fmaller 

 compais, by returning upon itfelf at every tenth link, are 

 likewife ufeful in prefenting a horizontal furface, to which 

 fmall circular pieces of brafs are fcrewed, with figures i, 2, 3, 

 &c. to 9, engraved on them, denoting the decimal parts of the 

 length. Thus the middle crols-joint, or that which feparates 

 the 50th from the 51 ft link, is fhewn in the Plate with the 

 figure 5 upon it. 



The chain, in its firfl confl:ru6!:ion (for we are now to point 

 out fon:ie alterations that were afterwards made in it), was one 

 hundred feet in length, including the two brals handles ; in 

 "the extremity of each of which there Wxas a femi -circular hole, 

 of the fame diameter with the fleel arrow^s fucceffively fixed 

 in the ground, and ferving to keep the account of the number 

 of chains, when applied to common meafurement. In this its 



firft 



