. Railroad construction. Theory and practice . od of use may perhaps be bestexplained by an example. Let Fig. 5 represent a section per-pendicular to the survey line—such a section as would be madeby the dotted lines in Fig. 4. C represents the station elevation as determined by the level is, say, abovedatum. When the Locke level on its five-foot rod is placed atC, the level has an elevation of Therefore when a pointis found (as at a) w^here the level will read on the rod, thatpoint has an elevation of and its distance from the centergives the position of the 1
. Railroad construction. Theory and practice . od of use may perhaps be bestexplained by an example. Let Fig. 5 represent a section per-pendicular to the survey line—such a section as would be madeby the dotted lines in Fig. 4. C represents the station elevation as determined by the level is, say, abovedatum. When the Locke level on its five-foot rod is placed atC, the level has an elevation of Therefore when a pointis found (as at a) w^here the level will read on the rod, thatpoint has an elevation of and its distance from the centergives the position of the 160-foot contour. Leaving the longrod at that point (a), carry the level to some point (6) such thatthe level will sight at the top of the rod. h is then on the 165- 12 RAILROAD CONSTRUCTION, §12. foot contour, and the horizontal distance ah added to the hori-zontal distance ac gives the position of that contour from thecenter. The contours on the lower side are found first rod reading will be , giving the 155-foot Fig. 5. Plot the results in a note-book which is ruled in quarter-inchsquares, using a scale of 100 feet per inch in both the work up the page; then when looking ahead along theline, the work is properly oriented. When a contour crosses —
Size: 2167px × 1153px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorwebbwalt, bookcentury1900, bookdecade1900, bookyear1903
