PREPARATORY MAPS AND DATA 23 



100 feet deep can be very expeditiously made in common soil 

 or clay. In addition, the auger will bring up samples of the 

 material passed through in sufficient quantity to determine 

 the nature of the soil. (Baker.) A post-hole auger in dry soils 

 will reach depths of 10 to 12 feet and bring up the soil. A more 

 satisfactory method in some respects is to follow the work of 

 the engineers for the Rapid Transit Commission in New York 

 City in sounding for rock on Broadway, which was as fol- 

 lows: 



" Here two or three lengths of 2 -inch pipe were driven 

 first to serve as a casing. In order to drive this pipe a small 

 portable pile-driver was used, the top of the pipe being covered 

 with a protecting cap. The hammer, weighing 150 pounds, 

 was directed between four light metal guides, and had a fall of 

 about 6 feet, the whole arrangement being supported on a cast- 

 iron stand. The hammer was raised by hand-power. After 

 the casing had been put down, the protecting cap was removed 

 and a tee screwed on in its place, and down the pipe was inserted 

 a f-inch wash-pipe with a chisel-point, in the corners of which 

 were two small holes. Water was forced into this wash-pipe 

 while two men worked the pipe down by hand. The water 

 thus discharged, washing the sand away from the foot of the 

 wash-pipe, flowed upward between the wash-pipe and the 

 casing, carrying the sand with it. This water and sand flowed 

 out of the side opening on the tee at the top and was caught 

 in a bucket and sampled by the inspector in charge."* 



These borings were made at an average rate of 6 feet per 

 hour, three laborers and an inspector being employed on each 

 machine. The soil was sand and gravel, and about f of each 

 boring was cased. 



Patton, in his treatise on Foundations, gives the following 

 method as satisfactory: A 3- to 8-inch pipe of terra cotta or 

 iron is pressed into the ground as far as possible; then a long 

 narrow bucket with cutting-edge and a flap-valve a little dis- 

 tance above the cutting-edge, opening inwards, is lowered into 

 * Am. Soc. C. E., Vol. XXVIII, p. 13. 



