Engineering and Contracting . The rates of wages were as follows: Drill runners $ per day Jjaborers per day Blacksmith per day The speed of drilling varied greatly owingto the varying hardness of the rock. Some-times the performance of the two drills wasas high as 80 ft. per 0-hour shift, and some-times it was as low as 50 ft., but the aver-age drilling performance was 60 ft. of holeper day, or more, which is equivalent to about7 ft. of hole per hour in trap rock of averagehardness. The very poorest record for a sin-gle days work with one drill was 10 ft. ofhole. Taking the avera
Engineering and Contracting . The rates of wages were as follows: Drill runners $ per day Jjaborers per day Blacksmith per day The speed of drilling varied greatly owingto the varying hardness of the rock. Some-times the performance of the two drills wasas high as 80 ft. per 0-hour shift, and some-times it was as low as 50 ft., but the aver-age drilling performance was 60 ft. of holeper day, or more, which is equivalent to about7 ft. of hole per hour in trap rock of averagehardness. The very poorest record for a sin-gle days work with one drill was 10 ft. ofhole. Taking the average figure of 30 ft. per Iday per drill, the labor cost of drilling wouldbe 8% cts. per foot of hole. The blacksmith and his helper devoted about ]seven hours of the nine sharpening the both drills not more than 8 ins. of steelbroke off and caused trouble during three ]months of work. The power plant for this job consisted of aportable Ames steam boiler carrying about 80lbs. pressure. The water was fed to it by an. Fig. 2. View of Power End of JackhamerDrill. injector, the consumption averaging about 192gals, per day. During the first eleven weeksof constant operation about. 4Vi tons of softcoal were consumed. Leading from the boiler was a 1-in. ironpipe which crossed the road and connected Februarv 4, VJl-i. Engineering and Contracting 175 Aith several lengths of pipe of the same diam- connecting the drill feeds. When it became pipe were unscrewed and connected to theiter, laid along the ground beside the trench. necessary, with the advance of the work, to front. The drill feeds were \ in, rubberI his pipe had tees at convenient distances for move the boiler along, the back lengths of steam hose Methods of Constructing a Short Rock Tunnel on the New Low Grade Line Between Milwaukee and Sparta, Wis., Chicago & Northwestern Ry. Contributed by L. J. Putnam, Principal Assist-ant Engineer, Chicago, 111. DESCRIPTION, During the construction of the Chicago &Sorthwe
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