22 



SEWER DESIGN 



ing News, Vol. XXI, p. 423. The cost is given as not more 

 than $25, and it is said to bore through earth of any kind to a 

 depth of 28 to 30 feet. The drill-rod should be square, and the 

 flare of the chisel-point about ^ inch on each side. The iron 

 cross-bar is made of bar iron, ij inches square and about 4 

 feet long, with an eye for the drill-rod forged in. The CrOSS- 



Triangular Piece Pivoted 



in Pipe Cap, 

 with rings for guys. 



FIG. 3. 



bar is held to the drill-rod by a set-screw f inch diameter, and 

 holes in the drill-rod allow the placing of a f-inch pin for the 

 lifting-chain to bear against. 



Fig. 3 shows in detail another form of driver (Engineering 

 News. Vol. XXI, p. 484), the construction and arrangement 

 being sufficiently well shown in the drawing. 



With a common wood-auger i^ inches diameter, with exten- 

 sion-rods keyed on, and with levers 3 feet long, borings 50 to 



