The steam escaping by pipe 4, curved and immersed in the water in box E. which is supplied by pump F, it is condensed, and the water formed descends by pipe 5 into supply pump G, and is forced into the boiler again by pipe 6.
But boiling decomposes water, slowly changing it into air incondensible. Therefore the shifting valve 7 is necessary. This valve lifts at every puff of steam, and a small quantity of air escapes ; and it shuts, and a vacuum is instantly formed, as the crank passes the dead points.
The small waste of water may be supplied by con densing part of the steam rising from the condensing water. to run down the pipe 9, through a hole in the key of a stop-cock, 3 1 parts of an inch diameter. A small hole indeed to supply a boiler of twenty horses power.
No sediment can accumulate in the boiler, it being supplied by distilled water. Therefore it will last much longer, and require less fuel than others. Mud dy, limestone, or salt water, or the juice of the sugar cane, &c. &c. may be used to condense ; and as the engine works equally well while we boil away the con densing. water, we may boll for salt, sugar, &c. in working the engine,—thus using the fuel for double purposes.
If the steam be confined by the load on the safety valve, to raise its power to 100 pounds to the inch, area of the piston and the cylinder be nine inches in diameter, and the stroke of the piston three feet, the power will equal that of twenty horses, and will grind 20 bushels of grain per hour, or saw 5,000 feet of boards in 12 hours. If the steam be confined by 150 pounds, the power of the engine will be equal to 30 horses, when the steam is shut off at one third of the stroke, and striking thirty-six strokes per minute.— Double strokes double the power.
The more the steam is confined, and the shorter it be shut off by the regulator 8, the greater will be the power obtained by the fuel. For every addition of 30 degrees heat to the water doubles the power. So that doubling the heat of the water increases the power about 100 times. On these principles fuel may be lessened to one third part consumed by other engines.
This engine is not more than one fourth the weight of others; is more simple, durable, and cheap, and more suitable for every purpose; especially for propelling boats and LAND CARMAG?S. It requires no more water than the fuel will evaporate in steam, and this steam may be employed to warm the apartments of factories ; or the condenser E could be used as a still to distil spirits; or a vat for paper making, boiler iu a brewe ry, dye factofy, &c. &c.
To the preceding account of Mr. Evans, the follow ing may be added, taken front the preface to "the Steam Engineer's Guide." In the year 1787, Mr. Evans explained to Captain Masters at Annapolis, Maryland, at his request, the principles of his Columbian Steam Engine, that he might communicate them to the people of England, to propel carriages and boats : and in 1794 or 1795, he sent drawings and descriptions to England by Jo seph Stacey Sampson, of Boston, to endeavour to get some one to take out a patent there on shares with him; but he wrote from London that he could find no one to believe that the scheme would prove useful. Mr. Sampson died in London. In 1803 he entered into a contract with Mr. Edwards, engineer from Eng land, and spent two months in furnishing him with complete drawings and descriptions of his engine, in exhaustible steam engine, and volcanic steam engine, all of which he said he could set tip with his own hands. Ilis Columbian high pressure engine was erected in Philadelphia in 1801, and in 1802 Messrs. Trevethick and Vivian took out their patent in Eng land for a high pressure engine, which Mr. Galloway says, " has been found the most compact, simple, and effective engine perhaps ever known." The following. handbill was published by Mr Evans as a circular, and it will be useful to insert it on the present occasion. He may Unduly estimate the econo my of his engine, but H. he is wrong, as much may be said for several philosophers a Ito have undertaken to give tables of the expansive power of steam, no two of whom agree as to the results of their experiments or calculations.