706 Mr. hutton’s Calculations to afcertain 
ing i ’7 64 the breadth of the 63 iron pins, the fum is 
41 83*033 for the length of or . (3 uncorredled. 
But 62-38^=23!, therefore - 234 
29 
2700 
^0*4183 
= - 1*056 is the reduction on account of the ftate of the 
thermometer, which being applied with its proper fign, 
there refults 4181*977; and from this laft number de- 
ducting again yj—th part or *232, on account of the 
wearing of the brafs ftandard, there then remains 
4x81*745 feet for the length of the part a/3 of the bafe 
in Rannoch, as meafured by the chain. 
But as the chain was meafured not at the fame time 
with the bafe, but between two and three weeks later, 
when the air was probably cooler, the reduction above 
made for the ftate of the thermometer is perhaps fome- 
thing too great, and we may fafely conclude a/3 to be 
equal 4182 feet as meafured by the chain. 
a. The whole bafe «/ 3 y was next, on the 10th, 1 ith, 
and 1 2th of October, very carefully meafured by the 
twenty-feet meafuring rods. The rods at that time mea- 
20 ft. + 1*306 inch. = 20*io 8{ j ^ . 
20 ft. + x*354inch. = 20*1 1 2{ J 5 
the thermometer being then at 40°. The number of 
rods and the additional parts were as follows. 
fured thus 
’{b = 
a+4’49 
