A deep stratum of chalk would be penetrated by boring, for which purpose a tube of large diameter is necessary. A frame, which holds the first length of tube in position vertically, is set over the selected spot. The lower edge is not sharp, but rough jagged, and the work is performed by revolving the tube by means of a portable engine and horizontal pulley wheel on the frame through which the tube passes and to which it is wedged; a bag of sand placed on the top of the tube adds weight when required. When one length is nearly down, the boring is stopped and dredging commenced. A heavy piece of tube, about 21/2 ft. or 3ft. long and small enough to go inside the well tube, has its lower end edges slightly sharpened and is fitted with a valve; a small bar is riveted across the upper end, and filed off flush outside. To this bar is attached a piece of strong cord - that known as "cod line" is suitable. By repeatedly dropping this down the welltubeand pulling it up and emptying, etc., the borings are withdrawn: when advantageous, water is poured in.

Lengths of tube are added as the boring proceeds.