The problem of feeding boilers has yet to be solved, no method yet introduced having by its intrinsic merits superseded all others. At the present time, injectors or donkey-engines are usually employed—the former being an ingenious apparatus which forces the feed-water into the boiler by the rush of steam through a narrow orifice; the latter differing in no way from an ordinary pumping-engine, and usually deriving its power from the boiler itself. Both these systems of feeding require constant supervision; and it is to obviate the necessity of continued attention and the risk resulting from carelessness, that boiler-feeders automatic in action have been designed. So far, their application has not been extensive; but a recent improved design, patented as ‘Mayhew’s Automatic Boiler-feeder,’ bids fair to push its way even in these times of depressed trade, when boiler-owners not unnaturally hesitate to incur any outlay, however slight, which a rearrangement of the boiler-feed necessarily entails. The apparatus consists essentially of two vessels—the upper of copper, the lower of cast-iron. An ingenious valve-arrangement connects the former with the boiler, whilst the latter is connected with the supply of feed-water. When the water in the boiler falls below a certain level, the end of the pipe connected with the upper vessel becomes uncovered, and the steam being free to enter it, operates on the valves, thereby admitting a charge of water to the boiler from the copper vessel. A vacuum is formed in the copper vessel, which now recharges itself from the one beneath, ready for another operation. As many as five charges a minute can thus be obtained. Should the apparatus, from any cause, fail to work, and the water fall too low, a fusible plug melts and sounds an alarm whistle. It is satisfactory to note that an ingenious straining arrangement works well for feeding with dirty water—the great difficulty in all apparatus of this class, owing to the valves becoming choked. The feeder may be regarded as safely beyond the mere experimental stage, a large number already being in operation in different works throughout the country, and with results satisfactory in every respect. SHOT-FIRING IN COAL-MINES.