Wentworth, G. A. (George Albert), 1835-1906 · Boston, Ginn & company · leaf 180
the centre of the plate at thetop of the tripod a plumb-bob is suspended by which thecentre of the compass can be placed directly oyer a definitepoint on the ground. * The instruments described on this and the following pages are adjustedby the maker. If they should require readjustment, full… … INSTRUMENTS AND THEIR USES. § 6. Uses op the Compass. To take the bearing* of a line. Place the instrument so thatthe bob will be directly over one end of the line, and level by-pressing with the hands on the main plate until the bubblesare brought to the middle of the spirit levels. Turn the…
Trigonometry · Surveying · Navigation
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