Public works . EXCAVATING HARD CLAY IN HEADING WITH PNEUMATIC COAL PICKS WITHOUT THE USE OF EXPLOSIVES MILWAUKEE WATER WORKS TUNNEL, 448 PUBLIC WORKS \^0L. 52, No. 24 pits or trench work where thereis room enough fora man to work and even where there is not suffi-cient clearance for him to use an ordinary shovelor spade. In the Detroit district the soil tunnelled throughvaries greatly, from a very soft pumice-like cla_\to very hard clay. In one section medium hard clayis found full of sand pockets and ordinary hand exca-vation requires great care on account of the dangerof falling roof, and wo
Public works . EXCAVATING HARD CLAY IN HEADING WITH PNEUMATIC COAL PICKS WITHOUT THE USE OF EXPLOSIVES MILWAUKEE WATER WORKS TUNNEL, 448 PUBLIC WORKS \^0L. 52, No. 24 pits or trench work where thereis room enough fora man to work and even where there is not suffi-cient clearance for him to use an ordinary shovelor spade. In the Detroit district the soil tunnelled throughvaries greatly, from a very soft pumice-like cla_\to very hard clay. In one section medium hard clayis found full of sand pockets and ordinary hand exca-vation requires great care on account of the dangerof falling roof, and work executed with monkeyholes and power or hand knife was hazardous andrequired constant attention to timbering and sheet-ing. In this case the use of the pneumatic clay diggerenabled the miner t@ feel his way along and timberin advance of dangerous conditions. A 10^-foot diameter sewer is now being builtin tunnel within a mile of the above mentionel localityand is being excavated through clay so hard that nooth
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectmunicip, bookyear1896
