Davies, Charles, 1798-1876 · New York, Cincinnati [etc.] American book company · leaf 363
by vernier to thousandths of a foot,a spirit level E, by which the bar may be made truly horizontal,and an extension bar C, which may be drawn out 4 to 6 feet, 356 ELEMENTS OF SUKYETING. [book X. making the extended bar 14 to 18 feet long; when the bar is drawnout, the reading is made by a vernier… … Fig. 184, extended leveling rod is read (see Art. 290). The vertical bar,B, also carries a graduated scale, reading by vernier to thou-sandths of a foot. The two clamp-screws, FF, working againsta clamp-plate, fasten the horizontal to the vertical bar and keepit firmly in position, both…
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