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place where the llant pole was faftened to the upright 
pole, for fupporting the meafuring poles at a convenient 
height above the ground. In meafuring the bafe, one end 
of a pole wasfupported on one of the hands, and the other 
end on another hand ; and it was fet horizontal by means 
of a fpirit level laid on it about the middle, and by raif- 
ing or depreffing the arm on which it relied at one or 
the other end. The other pole was then, in like man- 
ner, Supported on the two other hands truly level, and 
in the fame vertical plane with the former pole, namely, 
that of the intended bafe, without regarding whether 
they were exachly of the fame height, and with fome 
fmall horizontal interval between their ends. This in- 
terval was meafured by laying one leg of a brafs redlan- 
gle, which was divided into inches and tenths, along one 
pole, while the other, or vertical leg, touched the end of 
the other pole: for it was not thought advifeable, to 
bring the ends of the poles to touch exactly, as that would 
have taken up a great deal of time, and might have en- 
dangered the altering the politionof the hindermoll pole, 
if it fhould chance to receive any fliock by laying down 
the foremoft pole. It is evident, that the inches and tenths 
given by the divilions of the brafs rectangle are to be 
added into one fum together with the poles, in computing 
the length of the bafe. When the foremoft pole was truly 
placed, and the interval between them had been mea- 
fured by the divided lide of the brafs rectangle, the hind- 
ermoft pole was taken up, and the hands on which it hatl 
relied were advanced forwards, and the pole again laid 
on 
