[Illustration: SCIENTIFIC AMERICAN] [Entered at the Post Office of New York, N. Y., as Second Class Matter.] A WEEKLY JOURNAL OF PRACTICAL INFORMATION, ART, SCIENCE, MECHANICS, CHEMISTRY, AND MANUFACTURES. Vol. LVI.--no. 9. ] [NEW SERIES.] ] NEW YORK, FEBRUARY 26, 1887. [$3.00 per Year. IMPROVED CALORIC ENGINE. Caloric engines have long been used by the Trinity Board to provide power for working siren fog signals in connection with their lighthouses in England. They have generally been in the past of the horizontal type, but lately a new pattern, which we illustrate from _Engineering_, has been brought out; and as the entire work of the motor consists in driving air-compressing pumps, this form of engine should give very good results. At one end of a beam stands the retort or furnace with the motor cylinder, and at the other end stand three pumps. One of these forces air into the furnace, a second supplies the receiver of the fog signal, while the third, which is smaller than the second, performs the same office, when it is desired to raise the pressure to a point too high for the larger pump to accomplish. As fogs come on very suddenly, and give so little warning that it is often impossible to get the engine into action before the vision is entirely obscured, it is customary to keep a store of air in the receiver at two or three times the usual working pressure, and it is from the accumulation of this pressure that the smaller pump is provided. The furnace is a closed receiver, and is fed with coke. Air is pumped into it at a pressure of about 30 lb. to the square inch, part being delivered below the fuel and part above. That part which goes below rises through the incandescent coke, and appears at the surface as carbonic oxide. Here it meets the upper air supply and burns with a fierce bright flame, producing very hot gases, which are admitted to the cylinder and there expand, driving the piston before them. From experiments made by Mr. C. Ingrey with engines of this kind, it appears that they consume from 2¼ lb. to 2½ lb. of coke per brake horse power per hour, and thus provide power very economically. The engine is regulated by a governor, which varies the proportion of air admitted above and below the fuel, and thus alters the temperature of the gases admitted to the cylinder. The distributing valves are of the conical type, worked by tappets, and the fall is regulated by an air cushion. These engines, for there are a pair, have been constructed by the Pulsometer Engineering Company, Limited, London, for the Northern Lights Commissioners, and will be erected on a lightship, probably at the North Carr. Each engine is nominally of six horse power, but actually gives ten horse power. The motor cylinder is 24 in. in diameter, the air pump 18 in., and the compressing pumps 9 in. and 5 in. respectively, all with a stroke of 18 in. [Illustration: IMPROVED BEAM CALORIC ENGINE.]