Measurement of a Bafe on Houn flow -Heath. 
fixth ftation. The rods, being now compared, were found to 
agree with the ftandard ; and the temperature was 6 y 0 { o 
On Tuefday the 3d of Auguft, the rods were compared 
at 7 h. A.M. and found only to exceed the ftandard by one- 
Sixtieth of an inch. Being arrived at the middle of the forty- 
fird hypothenufe, a point correfponding 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 
flation. The meafurement was then continued to the north- 
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 
eourfe corresponded to the 1370th fliort rod of 240 inches 
each,, equal to 3-28800 inches, or 27400 feet. To which 
diftance we have yet to add 4.31 feet, being the 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- 
panfion, or redudion of the hypothenufal line, becomes 
27404.3 j feet. And here it is to be obferved, that the inter- 
fedion on the tripod terminating the 27400 feet only over-fhot 
the picket answering 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 fur face. 
The meafurement with the deal rods being fimihed, they 
were compared at 5 h. PM® and found to agree with the 
ftandard, the temperature then being 75°, 
Bxpanfion 
LII2 
