The greatest boro of any artesian wall i the world is said to bo that just eorapleted in Birmingham, Eugland, The diameter fixed was tho unprocedented oae of twentysix iuches and was accomplished by now and improved niachinery. Tho machina thus euiployed is desuribod as consisting of a very heavy bar of cast iron, nrincd at its lower end with a nutnber of cutting chisels, and suspended by a rope, whicb was in conueotion with a stoaui engine at the mouth of the well. - As it is wrougjit up and dov.'n by the engine, the tensión ut' tho rope gives a circular movement to the bar of iron suffieient to vary tbe positiou of the ohisels at each stroke of the instrument. The apparatus of somo well-borers has around tbe ehisels a cylindrical chaniber, which, by mouns of single val vea, rebeives and ï-etains the abraded portions of the rock This ohaatber, whtfth would not ho!d many pints, had, of eourso, to be raisod to the surface at short intervals for the purpose of beiug emptied of the dobii.5, thus iuvolving muu'h loss of tiuie. But, by iiioans ot' tho improved maobine, tbis operatiou is porfornmd in a vory différent way. A cylinder is omplujed, eigiit or nine inches in diameter, baviug a piston titted to it so as to fonn a pump, with oue valve at tho piston and another at the bottom of tbe cylinder. When t!ie pump sinks to the bottum of tbe wel!, tha piston, by its own gravity, siuks also to tho bottom, and suddeuly roversing the ongine and drawing up tho suekür, not only is tbe crushed debris drawn up. ];it also pieces of rook, sis or eiglit inehes ia diameter. By.this means six or sevea tous of matter ara drawu up pur hour.