127
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.
[NEW SERIES.]]
IMPROVED CALORIC ENGINE.
Caloric engines have long been used by the TrinityBoard to provide power for working siren fog signalsin connection with their lighthouses in England. Theyhave generally been in the past of the horizontal type,but lately a new pattern, which we illustrate fromEngineering, has been brought out; and as the entirework of the motor consists in driving air-compressingpumps, this form of engine should give very goodresults. At one end of a beam stands the retort orfurnace with the motor cylinder, and at the other endstand three pumps. One of these forces air into thefurnace, a second supplies the receiver of the fog signal,while the third, which is smaller than the second, performsthe same office, when it is desired to raise thepressure to a point too high for the larger pump to accomplish.As fogs come on very suddenly, and give solittle warning that it is often impossible to get the engineinto action before the vision is entirely obscured,it is customary to keep a store of air in the receiver attwo or three times the usual working pressure, and itis from the accumulation of this pressure that thesmaller 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. tothe square inch, part being delivered below the fueland part above. That part which goes below risesthrough the incandescent coke, and appears at thesurface as carbonic oxide. Here it meets the upper airsupply and burns with a fierce bright flame, producingvery hot gases, which are admitted to the cylinder andthere expand, driving the piston before them. Fromexperiments made by Mr. C. Ingrey with engines ofthis kind, it appears that they consume from 2¼ lb. to2½ lb. of coke per brake horse power per hour, andthus provide power very economically.
The engine is regulated by a governor, which variesthe proportion of air admitted above and below thefuel, and thus alters the temperature of the gases admittedto the cylinder. The distributing valves are ofthe conical type, worked by tappets, and the fall isregulated by an air cushion.
These engines, for there are a pair, have been constructedby the Pulsometer Engineering Company,Limited, London, for the Northern Lights Commissioners,and will be erected on a lightship, probably atthe North Carr. Each engine is nominally of six horsepower, but actually gives ten horse power. The motorcylinder is 24 in. in diameter, the air pump 18 in., andthe compressing pumps 9 in. and 5 in. respectively, allwith a stroke of 18 in.
IMPROVED BEAM CALORIC ENGINE.
Naval Architecture During the Last Half Century.
The annual lecture under the auspices of theGreenock Philosophical Society, to commemorate the