Page:The New International Encyclopædia 1st ed. v. 04.djvu/75

CALORIC ENGINE. 53 Ericsson (q.v. ). The engines of Ericsson dif- fei'ed from the Stirling engine in that they drew tlieir supply of air from the atmosphere at each stroke, heated it, allowed it to expand while doing work, then exhausted it again into the ex- ternal air; they belonged to the type of hot-air engine with temperature changes at constant pressure. The first engine was installed in the ship Ericsson in 18.52, but the idea dates from 1S33, and it enjoys the distinction of having been built on the largest scale and of having made the most noted failure of any hot-air en- gine. To Ericsson is to be credited also the term 'caloric engine,' which he applied as a sort of trade name to his Invention. Briefly described, Ericsson's first engine was designed for a 2200- ton seagoing ship : it was intended for 000 horse- power, but actually ran at about .300 horse- pov.-er. There were four cylinders, each l-l feet in diameter and having 6 feet stroke, and the en- gine ran at nine revolutions per minute. As stated above, the engine proved a failure after several attempts had been made to remedy its faults. First the 14-foot cylinders were removed and replaced by others, which also failed; and finally the engine was replaced entirely by a steani-engine. Afterwards Ericsson made an- other attempt to drive a ship by an air-engine. The Primera was built and iitted with horizontal engines drawing their supply from, and exhaust- ing into, an artificial atmosphere of high pres- sure. As in the former attempt, however, the CALORIC ENGINE. FIO. 2. ERICSSON OAIiOBIO ENGINE. heating surface proved inadequate and the avail- able pressure was too small to give much power, so that again steam was substituted after a short trial. Economizers were employed with both of his large engines, but in the small engines, to the design of which Ericsson turned his attention after the failure of his large motors, the econo- mizer was abandoned. Ericsson's first design for a small motor was brought out in 1800. and in 1880 the latest form for pumping purposes was produced. Fig. 2 shows this type of engine. The fire of coal or gas is below the cylinder d, which is water-jacketed at the upper end, x x. In tank pumping engines, the pimiped water cir- culates through the water-jacket. At A is the hollow displacing piston, and B is the working piston proper. The displacer is coupled to the bell crank k, and so to the crank e, to which the beam a is linked directly by g. These engines do not use less fuel than steam-engines of similar size, but as they require no water or licensed engineer, they liave come into considerable use. The Stirling engine and the Ericsson engine between themselves emljodied all the characteris- tic features of the several types of hot-air en- gines defined above. The Ericsson engine is an open-cycle, non-regenerating engine, with tem- perature changes at constant pressure: the Stir- ling engine wa.s a closed-cycle, regeneratingengine, with temperature changes at constant volume. The hot-air engines produced by other inventors of this kind of prime motor have resembled sometimes the Ericsson engine and sometimes the Stirling engine, but have had the details of oper- ation worked out in dift'erent ways. Two of these only need be mentioned for the purpose of illustration: The Wilcox engine, of whiclx large numbers were made about 1860 to 1865, was, like the Ericsson ship engine, an open-cycle, regenera- tive engine, with temperature changes at con- stant pressure. Its distinctive characteristic was a peculiar supply cylinder fitted with a piston operated from the main shaft. This supply cyl- inder took in the atmospheric air and passed' it through the regenerator to the operating cylin- der, where it was heated and expanded to per- form its work, after which it was exhausted through the regenerator into the external air. The Jlerrill engine, one of which of 10 horse- power was used for some years previous to 1885 to run a factory at Winchendon. JIass., worked on the same principle as the Stirling engine ; that is, it used the same volume of air over and over. It had two working cylinders, each of which was double-acting (see Steam-Engine), and two reverser plungers, which affected the transfer of the air between the heating and cool- ing devices. Jlention was made at the beginning of this article of hot-air engines employing previously compressed air. These are commonly known as compression engines. In them a constant quan- tity of air is constantly changed in volume, being compressed while cold and exjjanded while hot. There are usually two cj-linders, one cold and kept cold by a water-jacket or other means, and the otiier hot and kept heated by external means. The ])iston in the hot cylinder is gen- erally timed from one-sixth to one-quarter revo- lution in advance of that in the cold cylinder, whereby the air is first changed into the cold cylinder, sometimes through a regenerator, then compressed therein, then changed to the hot cyl- inder back through the regenerator, taking up again the stored heat, and finally expanded in the hot cylinder. The first engine of this kind seems to have been invented l>v Charles Louis Felix Franchot. a Frenchman, in 18.53, and it is de- serving of brief mention for the clear manner in which it illustrates the working principle. Hot and cold cylinders of difi'erent areas were placed side by side, as shown by Fig. 3, with their pis- tons connected to cranks 135° apart. The bot- tom of the cold cylinder. A, was connected to the