[ sai ] 
the difference of the tranfits of the pole-ftar and of a Pe- 
gafi, cc Andromedae, and y Pegafi, with their difference 
of right afcenfion, in the fame manner by which I had 
put the fedtor in the plane of the meridian, and found it 
to agree with the former meridian line within two mi- 
nutes. 
It remains to give an account of the manner in tvhich 
the two bafes were meafured ; one in a level fpot at the 
foot of the hill, to the Southward; and the other at the 
diftance of about 2j miles from the hill to the Nortlr- 
weft, in the plain of Raiinock. I caufed two mea- 
furing poles to be made of ftrait-grained weil-feafoned 
fir, in the form of fquare tubes, 3 inches fquare and lo 
feet long, and ftrengthened Avith fquare pieces within- 
fide at fever al diftances. Thefe were carefully compared 
Aviththebrafsftandard made by Mr. bird, the fame which 
was ufed in the meafure of the degree at Penfylvania, im- 
mediately before they were applied to the meafure of the 
bafes, and the height of the thermometer noted at the 
time in order to make allowance for the expanfion or con- 
tradlionof thebrafsftandardby heatorcold. Fourwooden 
ftands were provided for fupporting the poles ; each hav- 
ing a triangular bafe with three iron fpikes beneath, at 
each of the angles. An upright pole, fix feet high, rofe 
from the middle of one fide of the triangle, and two fliort 
braces were joined to it from the two ends of this fide, 
and a long flant pole from the oppofite angle. Two Aiding 
arms were put upon the upright pole, capable of being 
raifed or depreffed, one above and the other below the 
Z z z 2 place 
