Notes on military surveying and reconnaissance

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1882 Excerpt: ... rises and falls, should agree with the last reduced level. In this case it is the number 50. 73.--Construction Of A Section From A Levelling Register. For purposes of instruction it will be found desirable for the student to fill up the accompanying register, which is given in skeleton, by the information derived from the two previous sections. If right, he will find the highest hill to be 27.3 above the level of the surface of the water. (plate VII.) After the register has been completed, the section from it can be laid down with the greatest facility. Draw a datum-line AB, and on it mark off the lengths, 50, 40, 10, fec, in succession, on any scale from the column of distances. From these points raise or let fall perpendiculars to the extent indicated in the column of reduced levels on some still larger scale as. required by Section 19. Through the extremities of these perpendiculars the sectional line can then be traced. 74.--Running Contours With A Level. For the sake of continuity in the explanation, it was thought advisable to give in Section 71 the method of establishing, during a series' of levelling operations, the positions of 25-feet contours on the surface of a slope. They are marked as A. I., A II., A III. Down certain vertical-intersection lines, taken with the view of showing as much as possible the configuration of the ground, lines of pickets are run at equal vertical intervals. The angles of these lines must be taken, as well as the distances between the pickets. (plate VIII.) After several of these points have been thus marked by pickets, the actual tracing of the contours is carried out more expeditiously. A clinometer, or eye-level, is temporarily fixed on a. stick at any convenient height, say about 5 feet, and a cross bar is secured ...