SMALL WATER SUPPLIES. 



is shown in fig. 34, and its method of use will now 

 be obvious. With these rods, and the chisels, etc., 

 previously described and illustrated, small borings 

 can be done by hand. Larger ones must, of course, 

 be executed by motive power. The up and down 

 motion is, of course, simple enough, but the rotary 

 motion is not quite so positive. It is usually effected 



Screwed' 





FIG. 32. FIG. 33. FIG. 34. 



by two cast-iron collars fastened to the top bar by 

 collars, one above the other, with a space between. 

 The two edges closest to each other of the collars, 

 viz., the top edge of the bottom collar and. the bottom 

 edge of the top one, are cut with teeth like a ratchet 

 wheel, while a toothed bush works between therru 

 These teeth, however, are specially cut, so that those 

 which engage with the top collar are one half pitch 

 in advance of those which engage with the lower 



