The plug, with a canvas cistern, is the easiest mode of obtaining water; the plug-box being only the size of a paving-stone, is no annoyance in the street, and the water has only one angle to turn before it is delivered. On the other hand, where the supply of water is limited, the plugs give but little command of it; there is, however, comparatively very small loss at a large fire in London from this cause, as it is very seldom that all the fire-engines can be supplied direct from the plugs, and those that arrive late must pick up the waste water as they best can, by using another description of canvas dam, or opening the street; but in enclosed premises, especially where the water is kept for the purpose of extinguishing fires, firecocks are much to be preferred. It is very difficult to insert the standcock into a plug if there is a considerable force of water, and if the paving has moved, it cannot be done without raising the plug-box; but this is, however, the easiest mode of using firecocks, and where there is a considerable pressure of water, if the watchmen or the police are supplied with a hose-reel and branch-pipe, they can, in enclosed premises, direct a jet on the fire while the engines are being prepared, and if they cannot reach the fire, they will have water ready for the engine when it arrives. Inclosed premises are particularly mentioned, because the principal duty of the watchmen, in these cases, is to guard against fire, and their other duties being comparatively few, the men are not often changed, and they can be instructed thoroughly in the matter. With the general police of the metropolis it is quite different, their duties are so numerous and varied, that to add that of firemen to them would only be to confuse them. Firecocks, if kept at 9 inches to 12 inches below the surface, are easily protected from frost, by stuffing the opening with straw. The advantage which the double firecocks have over the single ones, is merely the increased water-way, as a firecock 3-1/2 inches diameter could not be so easily opened or shut, as two cocks of 2-1/2 inches diameter. One of the greatest objections to firecocks, is the very large openings required in the streets, the first cost and the repair of which are both considerable, besides their liability to accident. To take them to the footpath, increases the expenses and diminishes the supply of water, as it is generally done with a small pipe, and the number of angles is increased. In some instances, where firecocks have been put down on one side of the street, no less than four right angles have been made in the course of the water; and if the fire happens to be on the opposite side of the street from the firecock, the thoroughfare must be stopped. The expense also is no slight consideration, for if laid along with the water-pipes, each firecock, if properly laid, and the pit built round with cement, will cost eight or ten times as much as a plug.