STATIONARY ENGINES.

197

to the main rods, a set off, or filling piece, being provided betweenthe stock of the pole and the main rod, to bring the axis of the polein a line with that of the pole case. Key-ways should be providedin the joint between the stock and set off, and also between the setoff and main rod; when the Staples and glands are firmly secured,the keys—of hard wood—should be driven. It requires great carethat the ‘pole Connection’ may be well made. Square nuts shouldalways be used for the pit work, because it is not always convenientto have snugly-fitting Spanners , and square nuts are then moreeasily managed than others. The stuffing box of the pole caseshould be packed with a well-made gasket and tallow.

“The working barrel of the ‘ drawing lift’ is bored a little taperfor 9 inches or 1 foot at the upper end, that the bücket may easilyenter when dropped in from above; sometimes a door piece is pro-vided above the working barrel, that the bücket may be examinedwithout the necessity of drawing it; but the plan is not a good onewhen forking, as the water may rise too fast, and if it gets abovethe door before the joint can be properly made the consequencebecomes serious. Directly under the working barrel is placed the‘ bull’s-head,’ which is, in fact, a supplementary valve box, availablewhen the ‘door piece’ is under water. The neck of the bull’s headshould be bored conical, and the valve seating geared similarly toan ordinary bücket, but the ring should be a little conical, that itmay be prevented from falling through the neck of the bull’s headand retained in its place. A wrought-iron loop or staple is providedon the seating, by means of which it may be fished up from abovewhen occasion requires. A small bar is placed across the staple,which acts as a guard to the clack valve. The ring of the bücketshould be of wrought iron, nearly the size of the barrel, parallel onits outer face and conical within. For the convenience of removingthe doors and replacing them again a chain with swivel and screwis sometimes used, suspended from a piece of timber above. Forthe facility of sinking, under the suction valve is suspended aturned pipe which enters a stuffing box placed above the wind bore.The wund bore is suspended in chains provided with lifting screws,for the convenience of low r ering as sinking proceeds. It will beseen that as sinking proceeds it becomes necessary to lower thedrawing lift constantly, and that it may be conveniently done thepumps are suspended in ‘yokes’ which take their bearings on tim-bers fixed across the shaft. Yokes are glands made to fit the body