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to cover the ftar, the telefcope was turned down to 
the horizon, and a land -mark was fixed up at the 
diftance of about half a mile, anfwering to the inter- 
fedtion of the wires. In like manner, by other ftars, 
feveral other marks were fixed up, and the mean of 
all was taken. In this direction the line PR was 
continued ; and though it was at firft intended to ex- 
tend it only to R, to the diftance of 10' of a great 
circle, it was in fadt prolonged fomewhat further, to 
S, PS being — 12,312 miles, or 10' 45" of a great 
circle. Now PC being™ 2,991 miles, or 2 / of 
a great circle, the angle NPC is = 89° 58' from 
whence NPS = 89° 55' 51" being fubtradted, there 
remains the angle SPC or tfPC — 3' 4", whence 
a C, or the diftance of the parallel PCR at C, fouth 
of a, fhould be 14,1 feet. But it having been made 
a rule, in dividing the provinces of Pennfylvania and 
Maryland, to trace out the parallels of latitude by the 
obfervations taken with the aftronomical fedtor only, 
the fedtor was put up at P and S fucceflively (fee 
fig. 1.) and the zenith diftances of the ftars Capella 
a Lyrae, and others, ’were obferved at both places j 
whence the point S was concluded to be 43 yards of 
129 feet — S Qjnore northerly than P ; and thence 
it was found by calculation, that the parallel of lati- 
tude PQjat the point C fhould be 454. feet, —a C 
diftant from the great circle P S, and to the fouth of 
the fame j and the point C was placed accordingly, 
bp laying off 454. feet™ a C, at right angles, to the 
line P a from the point a towards the fouth. 
a C found by the fedtor, being 454 feet, and found 
by the azimuth of the line PS being 14,1 feet only, 
it 
