SURVEYING THE ROUTE. 



freely through a hole in the shot, and the end A screws into a 

 gunmetal casting which contains a butterfly valve at C. The 

 shot is 'generally oval in shape, the longer diameter being 

 vertical. The sling and detaching gear at F are the same as 

 already 'described and Illustrated in Fig. 4. A set of three 

 tubes is sometimes used in this form. The shot being kept on 

 until the wire is picked up, the tube is forced deep down into 



Plunger. 



Trigger. 



Oetachabl* 

 Weight " 



Fig. 4. 



Fig. 5. 



Stallibrass Sounding Tube. 



the bottom until it reaches stiff ground, and the wad of this at 

 its lower end invariably secures the soft mud or ooze above it 

 which otherwise would be washed out before reaching the sur- 

 face. Samples are often 61n. to Tin. in length, and sometimes 

 show distinct strata. The mud is pushed straight out of the 

 sounding tubes into glass test tubes, which are then corked 

 and dipped in sealing-wax varnish. The detaching gear in the 



