 | Archibald Williams - 1905 - 458 strani
...area, forming a series of horizontal floors, built up from the bottom sets like the successive storeys of a house. The spaces between the timbers were filled...whenever the maximum degree of firmness was desired." So the delving was continued to two, three, four hundred feet. The Gould & Curry, Gold Hill, and Ophir... | |
 | Geological Survey (U.S.) - 1883 - 492 strani
...at the corners by four posts from 6 to 7 feet high, and capped by a frame-work similar to the base.2 The cappieces forming the top of any set were at the...were extracted with comparative ease and security. The early appliances for removing the ore and waste rock were of the simplest kind. The Ophir engine... | |
 | Hillary W. St. Clair - 1977 - 94 strani
...sets could be extended to any required height and over any area, forming a series of floors like the stories of a house. The spaces between the timbers were filled with rock waste to form a solid structure for maximum firmness. The square-set method was an outstanding... | |
 | 1933 - 912 strani
...by four posts from 6 to 7 feet high, and capped by a framework similar to the base. The cap pieces forming the top of any set were at the same time the...were extracted with comparative ease and security. Most mining methods are evolved slowly and are the result of the combined efforts of a number of minds;... | |
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The cappieces forming the top of any set were at the same time the sills or base of the next set above. These sets could readily be extended to any required height and over any given area, forming a series of horizontal floors, built up from the bottom... 