BORING 



437 



The chisels employed are of the ordinary description : whilst by hand boring, holes 

 of not more than a few inches diameter can be put down, with this apparatus holes of 

 any diameter to 18 inches can be bored without any difficulty. 



The rope is attached to the connecting piece by the clips, and is passed at the top 

 of the hole through strong iron clamps, A, over which it hangs loosely to allow for 

 the upward and downward motion of the boring-tools. The iron clamps are also 

 connected to a screw and slide, a, Jiff. 177, hanging from the end of the wood lever or 

 beam, this screw being used to adjust the length of the rope after it has been attached 

 securely into the iron clamp. 



The rope is drawn up by a small drum, D, driven from the same shaft as the 

 crank used for working the beam ; a brake being attached to the drum for the purpose 

 of lowering the chisel and connections into the bottom of the hole. This brake con- 

 sists of two pieces of timber, B E, which are drawn together by means of a rod and 

 screw. 



After the chisel has been at work for a short time, it is drawn up by means of the 

 drum D, and the pump F is then introduced, being lowered by the small drum o, which 

 has also a brake attached. This pump is worked up and down a few times, then 

 drawn up by the wire rope H, driven by the wheel on the main driving shaft. 



The engine used is an ordinary portable engine, with a cylinder 9 inches in dia- 

 meter. 



The boring rope is usually J inch in diameter, and is covered with tarred hemp rope 

 for protection. 



The depth from the surface, and thickness of the various strata passed through is 

 ascertained by observing tho wire rope, and by carefully noting the nature of the 

 samples drawn up by the steel pump. 



In boring with this machine, a small hole is sometimes kept in advance a distance 

 of about 4 feet, the sides of the hole being removed by the larger chisel, and the 

 pieces thus broken off are brought up by the pump, and kept in sample boxes. 



The average rate of boring varies from 10 to 20 feet per day of twenty-four hours. 

 It is usual, whether in boring by hand or steam power, to line the hole from the sur- 

 face down to the solid strata with tubes ; and should any loose strata, as sand, be 

 afterwards met with, tubes of smaller diameter than those first introduced are put 

 down, this necessarily causing a contraction of the hole, and also of the tools. 



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