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 171
es thatthe horizontal component is twice the vertical. In reading thisscale the edge of the vernier-arm is brought into coincidencewith the graduation. This instrument is very useful in giving approximate slopesin preliminary surveys, the instrument being pointed to a posi- 142 SURVEYING. tion as… … its use being evident from the figure. Thus, while the rod at0 is seen directly through the opening, the rod at p is seen in ADJUSTMENT, USE, AND CARE OF INSTRUMENTS. 143 the glass as the prolongation downwards of that of oy it beingreflected from the mirrors /and c in succession, they havingan…
Surveying
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
