G. H. HALLIGAN. LXXIX. 



half their full extent, or it became jammed between the tool and 

 the side of the tube, and prevented any movement one way or 

 the other. To get over this difficulty the improved appliance was 

 provided with a sliding shutter C, flush with the outside of the 

 tool. When the jaws are closed a wooden plug is inserted in the 

 conical hole B, thus keeping the jaws from opening until the tool 

 strikes the bottom. The force of the blow shears the wooden 

 plug, and the jaws at once expand. There is nothing to cause a 

 jam in the pipe, and the appliance cannot fail to act. The second 

 improvement was the lengthening of the distance from the ex- 

 panding plug E to the cutters F, thus allowing for less spring in 

 the steel jaws and less liability to injury at E. 



The method of driving the tubes through clay or soft rock, 

 where under-reaming is difficult and slow, is shown in Fig. 3, 

 and calls for no description. When it is necessary to keep the 

 pump going while hammering the tubes, the arrangement shown 

 in Fig. 4 is adopted. On account of the difficulty of getting any 

 cramps to hold on the smooth tube, no heavy driving can be done 

 with this appliance without injury to the pipe. 



The hinged spanner or cramp, shown in Fig. 5, was designed 

 to save time on the work. Most of the fishing tools, augers, 

 drills, etc , have already been described in detail in a report on 

 11 Drilling and Boring Artesian Wells, as practised in the United 

 States of America," by C. W. Darley, M. Inst. C.E., under 

 whom the author has the pleasure to serve, and to whom he is 

 indebted for much valuable advice and assistance in connection 

 with the work now being described. 



The sections of some of the bores carried out with the appara- 

 tus here referred to (Figs. 6, 7, 8), show that it is capable of valuable 

 work, and the attached statement giving the cost will show that 

 it is done at a reasonable rate. The cost of the work done out 

 of Sydney includes freight charges by steamer, rail or dray to 

 and from the work, as well as the fares of the men, repairs 

 to gear and incidental expenses, and the cost of raising the 

 tubes . 



