Meafurement of a Bafe on Hounilow- Heath.. 4jjf 



fixth ftatlbn. The rods, being now compared, were found to 

 agree with the flandard ; and the temperature was 67^1. 



On Tuefday the 3d of Aiigiift", the rod's were coinpared 

 at 7 h. A.M. and found only to exceed the ftandard by one- 

 fixtieth of an' inch. Being arrived at the middle of the forty- 

 lirft hypothenufe, a point correipondrng to the forward end of 

 the 1215th rod was transferred to the ground by the double 

 pickets and- filk-thread, as had been done at the twenty- feventh 

 ftation. The meafurement was then continued to the nortli- 

 weft extremity of the bafe, which was found in the whole to 

 contain 1353 complete long rods of 243 inches each +21 

 inches, where the tripod was placed, in the point which of 

 courfe correfponded to the 13 70th (hort rod of 240 inches 

 each, equal to 328800 inches, or 27400 ittX. To which 

 diflance we have yet to add 4.31 feet, being tiie fpace inter- 

 cepted between the interfedion on the tripod and the center of 

 the pipe marking the north-weft extremity of the bafe ; whofe 

 total length, as given by the deal rods, without regard to ex- 

 panhon, or redudion of the hypothenufal- line, becomes 

 27404.31 feet. And here it is to be obferved, that the inter- 

 fe£lion on the tripod terminating the 27400 feet only over- fhot 

 the picket anfwering to the 274th chain by two inches and 

 nine- tenths. But this nice agreement between the refult by 

 the deal rods, and that furnifhed by the rough meafurement 

 with the chain, arifes from the extra-length of this laft, which 

 fo nearly compenfated for all the irregularities of the furface. 



The meafurement with the deal rods being finifhed, they 

 were compared at 5 h. PM. and found to agree with the 

 ftandard, the temperature then being 75°. 



L 1 1 z Expnnjton. 



