Canadian engineer . eering Weekly PNEUMATIC CAISSONS AT FORT WILLIAM. By A. GILLIES, In the construction of the foundations for the Kaminis-tiquia River Bridge for the at Fort William, it wasfound necessary to use pneumatic caissons, in getting- downto bed rock, for the two main piers. A. C. Stewart & Company have recently finished theircontract for the foundation work, which proved to be a ratherdifficult proposition. The soundings showed bed rock atan elevation of from thirty to forty-five feet below waterlevel, and the central piers were required to have a levelbearing on sol
Canadian engineer . eering Weekly PNEUMATIC CAISSONS AT FORT WILLIAM. By A. GILLIES, In the construction of the foundations for the Kaminis-tiquia River Bridge for the at Fort William, it wasfound necessary to use pneumatic caissons, in getting- downto bed rock, for the two main piers. A. C. Stewart & Company have recently finished theircontract for the foundation work, which proved to be a ratherdifficult proposition. The soundings showed bed rock atan elevation of from thirty to forty-five feet below waterlevel, and the central piers were required to have a levelbearing on solid rock. As soon as the pneumatic caisson method was decidedupon, an up-to-date air plant was at once ordered. Thisconsisted of two Rand, Class C, air compressors, havingsteam cylinders 12-inch by 18-inch stroke and air cylinders15-inch by 18-inch stroke, 515 en. ft. each per minute at ; a 48-inch by 12 feet vertical air receiver; a water-tube aftercooler ; a 50 horse-power feed-water heater ; duplex \. 1. Caisson Under Construction. feed pumps; two duplex water supply pumps ; one high pres-sure air compressor, steam and air cylinders 6-inch by 8-inchstroke, capacity 50 cu. ft. per minute at igs with airreceiver, pneumatic wood-borers and drift bolt drivers; andtwo 50 horse-power locomotive type boilers. The caissons were 18 by 80 feet and built of BritishColumbia fir. (Fig. i.) The walls were of 12-inch by 12-inch timber^ caulked both inside and out, and planked out-side with 3-inch by 12-inch vertical plank, which was alsocaulked. The inside posts and struts were of 12-inch by 12-inch, and the braces of 8-inch by lo-inch timber, placed at6 feet 3-inch centres, and strengthened by i-inch steel strutand roof rods, the roof consisted of two layers of 12-inch by12-inch timber transverse and longitudinal; |^-inch by 36-inch drift bolts at 36-inch centres were used in the heavytimber and ^-inch by 7-inch ship spikes in the plank. The working chamber was 8 feet deep
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishertoron, bookyear1893
