California mines and minerals . ope are framed to fourteen inches on two opposite correspondingsides of each end, to a distance of three inches from each end. Thecaps are framed on one side at each end, leaving seven feet betweenthe joggles and about six-inch horns. A stope is started by breasting out the ore to the full width of thedeposit. Crosscuts are run into both walls, to be sure that all theore has been removed. The opening is then timbered with eight-footstope sets. If the ground is solid, no timbering is done until thewhole mass of the rock covering the area of the stop
California mines and minerals . ope are framed to fourteen inches on two opposite correspondingsides of each end, to a distance of three inches from each end. Thecaps are framed on one side at each end, leaving seven feet betweenthe joggles and about six-inch horns. A stope is started by breasting out the ore to the full width of thedeposit. Crosscuts are run into both walls, to be sure that all theore has been removed. The opening is then timbered with eight-footstope sets. If the ground is solid, no timbering is done until thewhole mass of the rock covering the area of the stope has beenremoved. The posts are then set in the solid rock, with six-inch 106 CALIFORNIA MINES AND MINERALS spreaders and twelve-inch rcund brace-sprags between the posts atthe bottom. A floor is then laid over the spreaders. If the rock is loose or soft, one set is put in at a time as fast asroom is made for them. In the soft ground heavy sills are laid, asshown in Plate IV, to give a solid foundation for the posts. Sills are. not, as is generally supposed, an advantage in working up under anold stope. Good floors laid across the spreaders, even though theyhave been in place so long as to be badly decayed, are found to bemore serviceable than sills. The sills are seldom in place whenreached, and have to be caught up securely, or they are liable, bytheir own movement, to start a serious run in the waste above the sill floor is opened and timbered (as shown in Plate IV,which represents a stope thirty-five feet wide), a raise following thefootwall is run up to the level above. This raise is necessary for the proper ventilation of the stope, aswell as the economical introduction of timber and waste into thestope; the timber and waste being thrown down the raise into thestope. The raise is located in the most convenient part of the stopeand, if possible, where there is a seam of gouge on the footwall,which greatly lessens the cost of the work by lessening the difficulty
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