212 FIRE EXTINGUISHER was at last sold and converted to other uses. To the city of Cincinnati belongs the credit of giving the first practical demonstration of the feasibility of this application of steam, and of making steam fire engines the basis of a fire department of unequalled efficiency. They are usually drawn by horses, one or two pair being used ; but in a few instances steam has been successfully employed to propel them. Such a one, made by the Amoskeag manufacturing company, was brought into use at the engine house No. 20 in New York city in 1873. ^ A view of it is given in the preceding engraving, in which 6 represents the boiler; &, the air chamber for compressed air ; c c, steam cylin- ders for working the pumps, p p, through ec- centrics not shown, moving at the same time the small balance wheel, over the pulley of which is seen a stout chain which passes over a drum on the axle of the drive wheel, Ji. The suction hose is attached at d, and the discharge hose at/, which is connected with the air chamber. The apparatus for steering is controlled by the capstan, gr, placed in front of the driver's seat. This engine weighs about four tons, and is ca- pable of propelling itself at the speed of a rapid trot. It has a capacity for throwing water through a If-in. nozzle to a height of 140 ft. and to a horizontal distance of about 250 ft. Through a 1^-in. nozzle it will throw a stream about 220 ft. vertically and 300 ft. horizontally. The usual working pressure of steam is from 60 to 80 Ibs. per square inch, the steam es- caping by a safety valve when above the latter pressure. When standing at the engine house the boiler is kept supplied with water and steam from a heater in the basement, at a pressure of about 70 Ibs. per square inch. The fireplace is kept charged with kindling wood and other combustibles, which are capable of supplying sufficient heat in one minute after ignition, during which time the water and steam supplied from the heater are capable of giving propelling force. FIRE EXTINGUISHER. Many attempts have been made to produce apparatus to extinguish fires by excluding atmospheric oxygen from the flame. Among the earliest machines of this kind was that known as Phillips's fire an- nihilator, which was made of several sheet- iron cylinders placed one within another. Water was contained between the two outer ones, which when heated generated steam and discharged it into an inner cylinder. Within the latter was the gas-generating mixture, a compound of charcoal, nitre, and gypsum. An apparatus for igniting it consisted of a bottle of chlorate of potash and sugar, upon which could be emptied another of sulphuric acid. A mixture of gases and steam was expelled from the top of the machine. An apparatus for ex- tinguishing fires was invented by MM. Carlier and Vignon of Paris, and patented by them in 1862, for which a patent was issued in the United States in 1869 and reissued in 1872. The principal advantage possessed by this ma- chine consists in charging water with carbonic acid gas and projecting it into the fire by the force of its own pressure. Such a machine, made by the Babcock manufacturing company of New York and Chicago, who own the Amer- ican patent, is represented in figs. 1 and 2. A FIG. 1. metallic cylinder, of sufficient strength to bear an internal pressure of over 250 Ibs. per square inch, contains in its upper part a glass or leaden vessel capable of holding 8 or 10 oz. of sul- phuric acid. It is suspended by two pivots placed upon opposite sides and below the cen- tre of gravity, but retained in an upright po- sition by means of the stopper, which is held in the mouth of the vessel by a rod which passes through the hermetically adjusted cover. About 7 gallons of water holding in solution 2^ Ibs. of bicarbonate of soda is placed in the large cylinder, and about 8 oz. of commercial acid is put in the glass or leaden vessel, and held in position by the stopper and the rod which passes through the cover. The latter is then clamped to its place, and if the stopper be re- moved the vessel will become inverted by its own weight and the acid precipitated into the solution of carbonate of soda. This causes the liberation of a quantity of carbonic acid gas, which at the ordinary pressure would occupy nearly eight cubic feet, but which under the pressure produced by its own elasticity, in this case about 100 Ibs. per square inch, remains FIG. 3. dissolved by the water. If a hose be attached to the stopcock placed in the lower part of the cylinder, a stream of water holding carbonic acid gas in solution is forced out Avith great rapidity, carrying with it bubbles of gas which
