An Elementary Course of Military Engineering Volume 1 (Paperback)

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. 1870 Excerpt: ... cap sill; the thickness of the top sheeting; and the thickness of the shaft frame; two inches for free space between the gallery frame and the shaft frame next above it, to introduce the top sheeting, and add them into one sum; subtract this sum from the total depth of the shaft, and divide the remainder into any convenient number of equal or unequal intervals, each not greater than 3 feet, for the shaft interval required. Example. Let the depth of the shaft, for example, oe 22 ft, and the height of the gallery 4 ft. 6 in. Then: From ground sill to exterior of top sill 4 ft. 11 in. Top sheeting 0" 1" Shaft frame 0" 4 " Free space 0" 2" Total... 5" 6i" This taken from 22 ft. leaves 16 ft. 5 in., which can be divided into four intervals of 3 ft. 4 in. each, leaving one interval of 3 ft. 1J in. which may be placed either at top or bottom, but better in the latter position. 10. Construction of Shafts. To construct the foregoing shaft in a loose soil, there will be required a top frame; five side frames for the intervals above estimated; two for the remaining lower portion of the shaft; one auxiliary frame; four battens for each interval, each of the length of the interval added to the thickness of the shaft frame; from twelve to twenty square pickets about 18 inches long; with the machinery and mining tools requisite for the operation. The work is laid out by first driving a picket to mark the axis of the shaft, and two others which, with the first, should be in the vertical plane containing the axis of the gallery. A level bed is then made for the top frame; the pieces of which are accurately laid and confined by pickets, one at the end of each piece; care being taken to drive the two pickets of each pi...