Book Description

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1901 edition. Excerpt: ...so much more labour entailed in fitting and joining, and these operations are so much simpler with square than with round timber, that the former is generally employed. When the level accommodates a double track, the stull-piece is reinforced by a post midway separating the tracks. ln loose ground, recourse must be had to spiling or fore-poling. which is conducted on exactly the same principles as the corresponding opcrution in shaft-sinking (see p. 205), viz. by driving planks or legs, pointed at one end and sometimes iron-shod at the other, over the cap of the last set, and in advance ot' the heading, giving them an upward tendency. When about halt'-set distance has been covered, a false or dummy set is introduced to relieve the spiling of some of the weight, and then the work is advanced till the time comes for inserting a true set. It is often necessary to join the last 3 or 4 sets with stout iron dogs, removing them as the settling ground fixes each set firmly in place. Sometimes the spiling must fit very closely, and packing of moss, stringy bark, or old bagging is required to keep the fine dry sand from running into the drive. V Cost.--So many conditions go to determine the cost of all mine work that a wide range of figures is encountered. At the Lucknow mines, New South Wales, with wages at 7s. (Ed. per 8-hour shift, the author found the cost of driving in the serpenline, along a good "joint," and just breaking the diorite footwall, to be about 24s. per ft.; with hand labour, sometimes as low as 17s. 6d. In driving through diorite, air drills were generally employed, the cost of passing through ordinary rock of this class being about 308. per ft. On the other hand, in some varieties of the diorite, short...