[ 27 6 ] 
in a day, and were often obliged to make ufe of the 
morning or evening twilight. 
In the continuation of the line, a perfon was left 
at the mark, behind the instrument, till another 
mark was fet forward, to prove with a plummet that 
its center was not moved. 
The viftocut through the woods, in this work, was 
about eight or nine yards wide, and, in general, feen 
about two miles, beautifully terminating to the eye 
in a point. 
The zenith distances of the Stars, for determining 
the celeftial arc, anfwering to the interval of the par- 
allels of the northernmoft and fouthernmoff points 
of the lines, were made with an excellent fedtor of 
fix foot radius, conftrudhed by Mr. John Bird. 
In the courfe of the work, for dividing the pro- 
vinces of Maryland and Pennfylvania, the fol- 
lowing lines were traced out, that offered 
themlelves for determining the length of a 
degree of latitude. 
In the following fig. let N reprefent the northern- 
moft point, and A the mod fouthern of the faid lines. 
Beginning at N, a meridian was traced from N to 
mil* cha. lin. 
P. — 14 64 H. In this line there were fome hills, 
which were meafured horizontally with a level, but 
the plains were meafured with a chain. 
In. ch. lin. 
P C — 2 79 27 ; C being in the parallel of lati- 
tude with P, which was determined by the fedtor. 
m* ch* lia. 
DC a meridian =. 5 2 43, in which are three 
or four fmall afcents and defcents. 
Th 
