This method has been generally disused, iron or wood rods substituted in the place of the rope, and a variety of augers and chisels instead of the simple chisel, with appliances for clearing the bore-hole of _débris_. Figs. 50 to 56 show examples of an ordinary set of well boring tools. Fig. 52 is a flat chisel; Fig. 53 a [V]-chisel; and Fig. 54 a [T]-chisel. These chisels are made from wrought-iron, and when small are usually 18 inches long, 2-1/2 inches extreme breadth, and weigh some 4-1/2 lb.; the cutting edge being faced with the best steel. They are used for hard rocks, and whilst in operation need carefully watching that they may be removed and fresh tools substituted when their sides are sufficiently worn to diminish their breadth. If this circumstance is not attended to the size of the hole decreases, so that when a new chisel of the proper size is introduced it will not pass down to the bottom of the hole, and much unnecessary delay is occasioned in enlarging it. In working with the chisel, the borer keeps the tiller, or handles, in both hands, one hand being placed upon each handle, and moves slowly round the bore, in order to prevent the chisel from falling twice, successively, in the same place, and thus preserve the bore circular. Every time a fresh chisel is lowered to the bottom it should be worked round in the hole, to test whether it is its proper size and shape; if this is not the case the chisel must be raised at once and worked gradually and carefully until the hole is as it should be. The description of strata being cut by the chisel can be ascertained with considerable accuracy by a skilful workman from the character of the shock transmitted to the rods. When working in sandstone there is no adherence of the rock to the chisel when drawn to the surface, but with clays the contrary is the case. Should the stratum be very hard, the chisel may be worn and blunt before cutting three quarters of an inch, it must therefore be raised to the surface and frequently examined; however, 7 or 8 inches may be bored without examination, should the nature of the stratum allow of such progress being made. [Illustration: Well-boring Tools. Figs. 50-56.]