The theory and practice of surveying. Designed for the use of surveyors and engineers generally, but especially for the use of students in engineering (1886)
Johnson, J. B. (John Butler), 1850-1902 · New York, J. Wiley & sons · leaf 578
is cut is from Fauths Catalogue, Washington, D. C. GEODETIC SURVEYING, 549 it is carried in the hand when the instrument is transported.A mirror is provided which enables the observer to read thebubble without moving his eye from the eye-piece. There is athumb-screw with a very fine thread under… … Fig. 149. delicate, one division on the scale corresponding to about threeseconds of arc. The bubble-tube is chambered also, thus al-lowing the length of the bubble to be adjusted to differenttemperatures. The magnifying power is about 45 diameters.There are three horizontal wires provided, set at…
Surveying
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