Although frum 20 to 30 fathoms is the common length of a lift or set of pumps, it sometimes is neces sary to make it much longer, when no place can be found in the shaft for fixing a cistern, on account of the tubbing ; from this cause a lift of pumps has been made of 70 fathoms in length ; but this requires uncom mon strength of every material, and such a length is only made front absolute necessity.
It is the practice to use the sinking set of pumps for sinking the whoa: depth, so that as soon as the first cistern is ready, a set of pumps, named a fixed set, is substituted lor the sinking set. In common practice, fixed sets of pumps are jotted together by flanges and bolts, but in the imp oven practice, all the fixed sets have spigot and faucet joints ; and the joints are made water tight by tappings of tarred &nine!. Bur the lower set of pumps of every engine ' as flinge joints, with strong !lofts, for the special put pose of mein being connected in one firm column, so that if the water should grow up the pit, or any leak happen in diem below water, the whole may be drawn up from the bot tom, if necesssry, and repaired; which operation could not be effected with the other kind of joints, as they would not hang together. In the case where there is only one lift of pumps, the flange-joints are for the saute reason used. The spigot and faucet joints render the drawing of pumps one by one. and placing and jointing them, a much quicker operation than when the other joints are used. In general, the operation may be per formed in less than a tenth of the time required for the other kind ; and it may be frequently of great set vice to have the upper half of the lower set with spigot and faucet joints, if there is no risk of the water rising very quickly up the shaft, of which there is generally little danger after the colliery is opened up and a suffi cient reservoir formed for the water.
With regard to the mode of collaring the pumps in the pit, keeping them steady, and in a true perpendi cular line, the old practice is, to have two buntons of about nine inches deep, and six inches in breadth, to pass close to the side of each pipe under the flange or joint. The ends of these are fixed into the shaft wall, and the other ends rest on brackets fixed to the brat lice wall ; the other sides of the pipe are collared by pieces of wood, named rackings, and in some cases stretch only the breadth of the buntons ; or, if the pit admits of it, one or both of them are fixed into the side of the shaft wall. The improved plae, in order to give
as much room as possible for the operations which are so frequently carried on in the engine pit where the pumps are, is to fix a strong bunton under the joint of each pipe ; to which buntons the pipes are firmly attach ed by a collar of iron, with screws and nuts, as represent ed Plate CCCXC. Fig. 13. By this plan there is much more room in the pit.
Though this mode of fixing the pumps is very suit able for all the upper sets of pumps, it is not so for lower sets, where from accidents to which they arc liable, the pumps are sometimes to draw up bodily. The mode of fixing with buntons and rackings is therefore preferred in the lowest set, and the fixtures are so made, that if there is not time to remove the buntons and rackings, the whole may be hove up. In cases where the buntons hold fast, they must be cut away under water by chissels fixed upon loaded spears.
With regard to the water which is found in sinking through the several strata, in ordinary cases it is con ducted down the walls of the shaft. If the strata are of a firm consistency, a hollow ring is cut into the sides of the pit in a spiral line down the shaft, and when the ring can hold no more water, the water is either conducted down in a square spout to the near est pit cistern, or a groove is made in a perpendicular direction in the shaft wall, and a square box either in• serted into it, flush with the sides of the pit, or it is co vered with deal fitted tightly to the cavity. Similar spiral rings are formed in succession downwards, and the water conducted always into the nearest pit cis tern. The improved plan is, to insert rings of wood or cast iron, flush with the sides of the pit, and the wa ter is conducted from one ring to another, by means of perpendicular pipes, until the under ring can hold no more water. \Vhen the water from that ring is car ried in pipes to the nearest cistern, then a new set of rings is inserted under these, and the water conducted in the same manner all the way down. As keeping a pit dry is an important point, great attention is paid to the doing of it well. When it happens in an engine pit that there are a great many beds of coal found in the shaft, a mine a few yards long is driven into each coal, and a bore put down from one coal to another, the water is gathered into each coal, and descends through the bores to the pit cisterns.