Manual of military engineering . *9Q€ if-ot. Plate SG tl Field Level. IbfoUawplxiteSS r CHAPTER XXII.—ROADS—BONING AND LEVELLING. 127 points (C, D, E) whose level is required to be known. Theboning rods being all of the same length, give by their topsa horizontal line parallel to the first line of sight, but 3 feet(or thereabouts) above It. In the same way a given slope(say y^^) can be set out (iig. 4) by arranging the tops of thefirst two pickets at the required slope (level A and B, 10 feetapart, and then cut 1 foot off B), setting up two boning rodson them, and by means of the third boning
Manual of military engineering . *9Q€ if-ot. Plate SG tl Field Level. IbfoUawplxiteSS r CHAPTER XXII.—ROADS—BONING AND LEVELLING. 127 points (C, D, E) whose level is required to be known. Theboning rods being all of the same length, give by their topsa horizontal line parallel to the first line of sight, but 3 feet(or thereabouts) above It. In the same way a given slope(say y^^) can be set out (iig. 4) by arranging the tops of thefirst two pickets at the required slope (level A and B, 10 feetapart, and then cut 1 foot off B), setting up two boning rodson them, and by means of the third boning rod driving inpickets to show the top of the slope at any required points,N, 0, P. Again, a continuous slope between any two pointscan be laid out with pickets, as in Fig. 5, by putting the firsfcboning rod at F, the second at G, and with the third rod settingup the intermediate pickets. 317. In taking a section it is usual to enter the levels, &c., Takingin a book {see page 122). section. Field The field level is shown in Plates 84, 85, and 86.
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