were a bore-hole, by chisels fastened to boring-rods driven by a steam-engine in the manner already described for smaller borings.
— Chalk over coal measure (Westphalia).  were a bore-hole, by chisels fastened to boring-rods driven by a steam-engine in the manner already described for smaller borings.  The arrangement of machinery on the top, though considerably modified, is somewhat similar to that shown in Fig.