4iO 



BORING 



36 



Fig. 32 is a tool used for cutting lining tubes when it is found that they cannot l>o 

 drawn out all at once, c exhibits a plan of the cutter. 

 Fig. 33 is a plug used for driving down lining tubes. 



In some cases it is required after the tubes have been inserted, to recommence 

 boring the hole, and make it of the same size as the outside diameter of the tubes. 

 To accomplish this object several ingenious devices have been designed. 



In. most of these the chisel intended to form the large diameter of the hole is passed 

 down through the tube flush with the sides of the tool, and when reaching the 

 bottom of the tube it is brought into position in several different ways. In one 

 case, a screw when turned, forces out the cutters. In another, the chisels are pushed 

 out by springs. 



Another mode is to attach to the moveable chisels a dry hemp cord, the contraction 

 of which when soaked in water draws up the chisels. 



In boreholes of a considerable diameter, a ' free falling ' arrangement, as shown by 

 figs. 35 and 36, is sometimes adopted. A A are pins, holding in a fixed position two 



long clutches, which hold the end of the boring 

 rods at E. The disc D is of the same diameter as the 

 hole being put down. When the sliding arms reach 

 the bottom of the stroke, the arrow-head E is caught, 

 and is drawn up to the top of the hole, as shown 

 by fig. 35. Immediately the down stroke commences, 

 the resistance against the disc, caused by the water 

 standing in the borehole, causes it to open the 

 clutches and disengage the tool. It will be seen that 

 this apparatus is only applicable where a column of 

 water is present. 



Having now described the tools used in the ordinary 

 modes of Boring, attention may be drawn to various 

 modern improvements in this science. 



A method of boring with hollow rods, combined 

 with a force-pump, was introduced about the year 

 1846 by M. Fauvelle, in order to obviate the neces- 

 sity of using the shell, the detritus produced by the 

 tool being removed continuously by a downward 

 current of water forced by the pump through the 

 interior of the rod, and rising in the annular in- 

 cluded space between the exterior of the rod and the 

 lining tube. In spite of the apparent advantages of 

 this method, namely, the maintenance of a clear face 

 of rock for the cutting tool to work on, and the saving 

 of time due to the abolition of the shell, and the 

 adoption of the method of continuous discharge, 

 it does not appear to have come much into use. 

 Eecently, however, a modification in which the dis- 

 charge of the detrition is effected by an upward 

 current of water through the rod, has been employed 

 to advantage in borings for petroleum in Western 

 Canada. 



I'auvollo's system of boring is probably the most 

 simple in existence, and has the power of boring at a quicker speed than other 

 machines. A short description of its mode of working may therefore be dpsirable. 

 The machine is driven by engine-power, in the manner shown in Jig. 178, p. 441. 

 The boring rods consist of ordinary steam tubing, 2 inches diameter, and jointed 

 together by union boxes. The chisels are welded into short lengths of tubing, small 

 holes being left at the bottom of the tube. Water is forced in at the top of the bore- 

 rods by means of a small force-pump, worked by a crank on a pinion-wheel, which is 

 connected to a larger pinion on the main shaft. The water from this pump is first driven 

 into an air-chamber, and is taken thence by india-rubber tubing to the top of the bore- 

 rods, from which it escapes at the bottom of the rods a few inches above the chisel point. 

 It is forced thence to the surface, carrying with it all the debris cut up by the chisel. 



This debris is caught in pots or settling troughs, and from a examination of these 

 the nature of the strata passed through is ascertained. 



Independently of this test, however, the man in charge of the machine constantly has 

 his hands upon the rods, and in this way can tell by the character of the stroke any 

 change of strata, which is at once marked upon the rods. 





