1measurement become a greater length than it
should be, he sets upon the
instrument a standing plummet level, the tongue of which, if the instrument
is level, indicates no numbers, but the point from which the numbers start.
instrument a standing plummet level, the tongue of which, if the instrument
is level, indicates no numbers, but the point from which the numbers start.
COMPASS. A, B, C, D, E, F, G ARE THE SEVEN WAXED CIRCLES.
When the surveyor has carefully observed each separate angle of the
tunnel and has measured such parts as he ought to measure, then he lays
them out in the same way on the surveyor's field20 in the open air, and again
no less carefully observes each separate angle and measures them. First of
all, to each angle, according as the calculation of his triangle and his art
require it, he lays out a straight cord as a line. Then he stretches a cord at
tunnel and has measured such parts as he ought to measure, then he lays
them out in the same way on the surveyor's field20 in the open air, and again
no less carefully observes each separate angle and measures them. First of
all, to each angle, according as the calculation of his triangle and his art
require it, he lays out a straight cord as a line. Then he stretches a cord at
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