The aim of this article is to describe the various contrivances employed in different industries and in everyday life both at home and abroad, for effecting the removal of liquids from portant liquid, of course, is water, but there are several, such as acids, whose corrosive nature renders the ordinary pump useless; and there are others, such as syrups, whose viscosity demands special provision. All these will come under notice; but not the modern pumping engines on a scale interesting only to the engineer, as these may be found in such works as 'spons' Dictionary of Engineering.' It will be convenient to divide this subject into 2 sections - pumps, and siphons.
Before proceeding to a description of the various forms of pump as now in use, there are many means of raising water that demand.
The simplest and most rudimentary method of raising water from a depth is by pended on a cord; the next step in advance is a bucket attached to a pole. These are only adapted for shallow depths. When the depth increases, the weight is too great for direct hauling, and a pulley must be introduced, as in Fig. 23. An improvement on this system, permitting a much larger quantity to be drawn at one time and from greater depths, consists in applying animal power to the free end of the rope, attaching it, for instance, as is very commonly done in India, to a suitably harnessed bullock, which is made to walk along a path of the correct length to suit the depth of draught. By constructing this path with a downward slope away from the well, the animal's weight is made to assist its muscular efforts. This arrangement is the churus or chursch of India.
Another development of the pulley system is seen in Fig. 24, where the full bucket is partly counterbalanced by the empty one, the latter being pulled down to raise the former.
In Italy, use is made of a very simple of a house without descending for the purpose. This is outlined in Fig. 25. One end of a strong iron rod a is fixed to the house above the window of an upper landing or passage, the lower end being secured in the ground on the far side of the well 0, and in a line with its centre. A ring which will slide easily over the rod is fastened to the handle of the bucket c, to which also a cord d is attached, and carried over a pulley supported above the window. When the cord d is slackened, the bucket descends in a diagonal manner till the ring reaches the stop e, which is bo arranged that at this point the bucket hangs directly over the centre of the well. On still further slackening the cord d, the bucket continues to descend, bat in a perpendicular direction, to the level of the water. When tilled, it is simply hauled up.
A great step in advance of the pulley, for lifting heavy weights, is the windlass, a cylinder made to revolve by crank-handles attached to one or both ends. The rope should have a bucket suspended from each end, so as to be in a manner reciprocating. The Chinese windlass illustrated in Fig. 26 furnishes the means of increasing mechanical energy to almost any extent, and is used to raise water from prodigiously deep wells. The cylinder a consists of 2 parts of unequal diameter, to the extremities of which, the ends of the rope are fastened on opposite sides, so as to wind round the 2 parts in contrary directions. As the load to be raised is suspended from a pulley 0, every turn of the cylinder a raises a portion of the rope equal to the circumference of the thicker part, but at the same time lots down a portion equal to that of the thinner, consequently the weight is raised at each turn through a space equal only to half the difference between the circumferences of the 2 parts of the cylinder. Hence the action is slow, but the mechanical power saved is proportionally great.
Another way of lightening the load is illustrated in Fig. 27, and consists in replacing a portion of the cylinder a by a "fusee" or cone-shaped drum b. One end of the rope is secured to the smaller end of the cone, and the other end of the rope to the bucket. While the full bucket is at a depth in the well (implying a greater weight to raise on account of the extra rope or chain attached), the winding takes place where the circumference of the fusee is least, and as the length diminishes the rope coils round the greater circumference. Thus white the work is hardest the speed is slowest, and while the work decreases the speed.
In another modification of the windlass, a cog-wheel is fixed to one end of the cylinder and moved by a pinion that is secured on a separate shaft, and turned by a crank. By proportioning the diameter of the wheel and that of the pinion (or the number of teeth on each) to the power employed, a bucket and its contents may be raised from any depth, since a diminution in the Telocity of the wheel from a smaller pinion is accompanied by an increase of the energy transmitted to the cylinder, and nice versa.
The crank handle of the windlass may be replaced by a drum-wheel at one end of the cylinder, of very much greater diameter than the cylinder (say a wheel 12 ft. in circumference and a cylinder 18 in.). The rope that supports the bucket is attached to the cylinder, while a second rope is made to coil round the drum. These ropes run in opposite directions, so that when the bucket is down the cylinder rope it uncoiled while the drum rope is wound up. By taking the free end of the drum rope over the shoulder and walking away from the well, the drum rope is uncoiled and the cylinder rope is wound up, thus raising the bucket.