. Supplement to Spons dictionary of engineering, civil, mechanical, military, and naval. ?-?=s^ ^ here but one-third of the quantity of slack is made, as compared with manual holing; and_ thisrepresents a corresponding increase in the value of the coal got, the slack being comparativelyworthless. Another advantage of machine holing is the increased rapidity with which the workcan be carried on ; a superior workman will undercut a face of about 5 yards of coal 3 ft. deepin aday of ten hours, in a coal of medium hardness, but this rate of progiess is exceptional; while amachine in the same time
. Supplement to Spons dictionary of engineering, civil, mechanical, military, and naval. ?-?=s^ ^ here but one-third of the quantity of slack is made, as compared with manual holing; and_ thisrepresents a corresponding increase in the value of the coal got, the slack being comparativelyworthless. Another advantage of machine holing is the increased rapidity with which the workcan be carried on ; a superior workman will undercut a face of about 5 yards of coal 3 ft. deepin aday of ten hours, in a coal of medium hardness, but this rate of progiess is exceptional; while amachine in the same time would undercut as much as 150 yards, or even more, to a depth of the pick action by hand labour most of the power is expended on the back stroke of the pickand in keeping it level. By turning a winch handle more than twice the power may be developed,and a wheel cutter actuated by this method by hand would be more effective than the pick action ;and this arrangement has been successfully adopted in Lilienthals manual-power coal cuttingmachine. One of the diflQculties in co
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectenginee, bookyear1879
