But the most complete and correct plan for lower ing the pumps in sinking, is the following, which was practised and brought into use by the Ne‘%eas.le en gineers. There are attached to the wind bore, or suc tion piece, two very strong ears, (see Plate CCCXCI. Fig. I.) having countet fort brackets upon the upper side ; in each of these is a squat e hole, Once and a half inches diameter, through which rods of iron are put and se cured by a strong,cotter at the under side of the ear. To these rods, U plates are attached ; these plates are fixed to wooden spears, six or seven inches square, ac cording to circumstances, and are connected together with side plates, in the same manner as pump spears. These spears are carried up the sides of the pumps, and close to the flanges, until they are as high as the top of the sinking set of pumps, or a few fathoms higher. Under each flange of the pumps, a lashing of pliable rope is passed round both the spears and the pumps ; this keeps the whole very firm and in a per pendicular direction. To the top of the spears. U plates are fixed, having a large strong eye at top ; to each of thesa eyes, a five-fold tackle is hooked, and the upper blocks or pulleys are suspended from strong wooden beams at the top of the pin The tackle-folds pass upwards from the lower pulleys, over single pulleys at each side, and are hove upon capstans till there is an equal bearing on both tackles. To the arms of the capstans, sledges are attached with ropes or chains ; these sledges are loaded with weights in proportion to the weight of the column of pumps, and as additional pumps are added, more weight is put into the sledges. By this very correct and mechanical arrangement, the sinking set of pumps, in the most gradual manner, and of their own accord, sink as the pit is sunk. and draw round the capstans. Before this method was adopted, the trouble, loss of time, and danger attending the lower ing of sinking sets, were uncommonly great. As the sinking set is constantly going down, and the point fur the delivery of the water always varying, a pipe of the same diameter as the pumps, but much lighter, is used, about eleven feet long, having a snort pipe cast neat Inc top. to which a hose or hoggar of leather is attached, of sufficient length to reach the cistern where the water is delivered. This is called the hoggar•pipe ; and in the course of sinking, as soon as the top of the hoggar is upon a level with the top of the cistern, the hoggar pipe is removed, a common pipe put in its place. and upon the top of Uri. pipe the hugger-pipe is ag sir fixed. In this manner the operation oh aiaking goes on, until the column of pumps has reached either the bottom of the pit, or the place fixed upon for having another set of pumps. A, is the sinking set of pumps, a, a, the ears through which the iron rods pass connected with the spears ; b, b, the spear ; c, c, the lashings ; d, the hog gar-pump ; e the hoggar ; f, f, the tackles; g, g, the single pulleys ; h, h, the tackle-fold leading to the cap stans ; i the pump spears.
In a sinking set of pumps, the wind-bore or suction piece, is not open at the bottom as in the other sets, which are fixed, but it is rounded and of a long form ; it is perforated with boles of from one to two inches diameter, where, besides the small holes, there is a large hole for admitting a man's hand, in order that the caeity may be at any time cleared of rubbish Iv filch may gather within it. When the workmen are sinking, the large hole is filled with a plug, having a projection of such length as renders it easily drawn at any time ; the work men have a number of plugs for the small holes, and when the operation of sinking begins, the upper tiers of holes arc plugged up, and the ingress of the water confined to the lower holes. By this plan, as the bottom of the suction-piece is kept in the bottom of the sump, or lowest part of the pit, the other part of the pit bottom is kept dry for the operations of the workmen. if the growth of water abates, more holes are plugged up ; if it increases, an additional number of them are opened. "%Viten the operation of sinking is suspended for any time, all the plugs are withdrawn in order to give full water way to the regular working of the engine ; and as much depends upon keeping the suction-piece safe, where it is exposed to violent strokes from the blowing up of the harder rocks, it is necessary either to wrap it round with old ropes, or to case it with staves of soft wood, which will not easily split. It is further to be observed, that
as in sinking, a vast quantity of air enters with the water every stroke of the engine, the pumps are filled with air and water together. On this account, the engine is wrought upon air, as it is termed ; and it is the object of the engine-keeper not only to make the lifting stroke very slow, but so to regulate the movement, that when the stroke is completed, the engine may stop several se conds before it makes the returning stroke, to allow all the air to ascend. IF the engine is working as a double power engine, the same kind of halt must be made at the returning stroke. This mode of working the en gine is now regulated either by water cataracts, or by air vessels attached to the gear of the engine ; or in small engines, the working is regulated by a man upon the hands of the engine, when the improved regulators are wanting. As the woe king barrels are generally nine or ten feet long, and the full stroke of the engine from seven to eight feet, when at regular work, it is the practice to lessen the length of stroke in sinking to about six feet, because, as the pumps are constantly going down, the bucket in the working barrel progres sively has its working space higher up. If the work ing barrel is ten feet long, and the restricted stroke of the engine six feet, and if the bucket is at the bottom of the barrel w hen the engine is ready to make its stroke, then the pumps can be lowered about four feet, ere the bucket be working at the top of the barrel. To this descent of the pumps particular attention has to be paid; and therefore, as soon as the pumps have sunk four feet, the spears and bucket are let lour feet lower into the barrel, and this is done at the top of the pit, when the spears overlap, and are fixed laterally by screwed glands.
The common depth for a set or column of pumps being from 25 to 30 fathoms, when this depth is at tained by the first set, preparation must be made for fixing the upper pit cistern, into which the tipper set of pumps is to be placed, and into which the water of the second set is to be thrown. If a strong bed of sand stone is found, a scarcement is left of the rock pro jecting about three feet into the pit, and is formed, in the course of sinking, into a chin or strong bracket, to support that part of the cistern upon which the upper set of pumps is to rest ; and a few feet under it, the pit is formed into its regular width. A recess is cut into the side of tile pit backwards from the brack et, for holding the cistern into which the upper set of pumps is to be placed. For the greater security of the place where the pumps rest, the recess is formed dove-tailed, about eleven feet back from the face of the bracket, from three to four feet in breadth, and about thirty inches in depth. Into this, a pit cistern bun ton is laid and firmly wedged, composed either of oak or of best foreign redwood pine, having the thick end laid into the back part of the recess, to prevent its corning forward into the pit, by the concussions and vibrations of the pumps, and in case of any failure of the bracket under the pumps. The inner end of this bunton is farther secured by blocks or chokes of wood, placed betwixt the upper side of the bunton and roof of the recess; similar chokes are placed upon the in ner end of the cistern. When the rock is of such a quality as not to be fit for forming a bracket, then a cross bunton of wood is substituted, from one to ehree feet in breadth, and from two to four feet in depth, according to the weight of the column of pumps to be supported. This bunton is fixed into the sides of the pit, and has a hold at each end from two to- four feet, according to the strength of the rock ; upon this the cistern is placed, having a recess, as before described ; sometimes logs eight inches thick are placed into the recess, at right angles to the cross bunion, firmly secur ed together, and upon these the cistern is placed.