Page:The American Cyclopædia (1879) Volume XV.djvu/349

 STEAM CARRIAGE 337 same time M. Servel conducted a series of ex- periments with a similar machine upon paved and upon macadamized roads, during what he described as the most trying of winter weath- er. He reports the following distribution of weight per cent. : Weight of locomotive 41-4 of wagons 18-2 " of paying load 40'4 Total. 100 The average total weight of three loaded wagons, which was the usual load, was 22,575 kilogrammes, or about 22 tons. The experi- ment was made in 1867-'8 of applying these engines to the towage of boats on the French canals, with very encouraging results. In 1871 several traction engines were exhibited before the royal agricultural society of England at Wolverhampton, and the judges made a se- ries of careful tests, reported in its "Jour- nal " for that year. The coal used on special trial amounted to 3*2 Ibs. per indicated horse )wer per hour, and the evaporation of water ras 7' 62 Ibs. per pound of coal consumed, the iverage temperature of feed being 175 F. he load drawn up the maximum grade of 564 ft. to the mile on Tottenham hill, which is ,900 ft. from top to bottom, was 26 tons, id including weight of engine 38 tons, giving coefficient of traction of 0*35. On a country >ad 16 m. long it drew 15 tons at an average te of 3 m. an hour, using 2'85 Ibs. of coal id 1-94 gallon of water per ton of useful >ad per mile. In October, 1871, Prof. R. H. mrston conducted a public trial of road en- ines and steam road rollers, on a well mac- " imized road at South Orange, N. J. Two steamers or traction engines and a steam roller were tried. The following are the rincipal dimensions : weight of engine com- plete, 5 tons 4 cwt. (11,648 Ibs.); diameter of cylinder, 7f in. ; stroke of piston, 10 , ; revolutions of crank to one of driving rheel, 17 ; diameter of driving wheels, 60 in. ; igth of boiler over all, 8 ft. ; diameter of )iler shell, 30 in. ; load on driving wheels, 4 >ns 10 cwt. (10,080 Ibs.). The boiler was of ordinary locomotive type, and the engine was mounted upon it, as is usud with portable igines. A representation of the engine is iven in the article PLOUGH (fig. 10). The en- ine valve gear consisted of a three-ported valve and Stephenson link, with reversing lever, as snerally used on locomotives. The connection itween the gearing and the driving wheels ras effected by the device called by builders }f cotton machinery a Jack-in-the-box gear, or differential gear. By this combination, the effort exerted by the engine is made equal at both wheels at all times, even when the engine is turning a corner. The weight of the steam road roller was 15 tons. The engine and boiler were of the same general dimensions as in the road locomotives already described. The whole machine was carried on ' four large wheels, with broad tread, covering a total width of 6 ft. Its weight exerts a compressive force of 5,600 Ibs. on each foot of width, or 467 Ibs. on each inch. The following is a summary of the conclusions deduced from the trial, and pub- lished in the " Journal of the Franklin Insti- tute : " A traction engine may be so construct- ed as to be easily and rapidly manoeuvred on the common road; and an engine weigh- ing over 5 tons may be turned continuously without difficulty on a circle of 18 ft. radius, or even on a road but little wider than the length of the engine. A locomotive of 5 tons 4 cw 4 -. has been constructed, capable of draw- ing on a good road 23,000 Ibs. up a grade of 533 ft. to the mile, at the rate of 4 m. an hour ; and one might be constructed to draw more than 63,000 Ibs. up a grade of 225 ft. to the mile, at the rate of 2 m. an hour. It was fur- ther shown that the coefficient of traction with heavily laden wagons on a good macadamized road is not far from -f%-$ ; the traction power of this engine is |qual to that of 20 horses ; the weight, exclusive of the weight of the en- gine, that could be drawn on a level road, was 163,452 Ibs. ; and the amount of fuel re- quired is estimated at 500 Ibs. a day. The ad- vantages claimed for the traction engine over horse power are : no necessity for a w limita- tion of working hours; a difference "in first cost in favor of steam ; and in heavy work on a common road the expense by steam is less than 25 per cent, of the average cost of horse power, a traction engine capable of doing the work of 25 horses being worked at as little ex- pense as six or eight horses. Railroad Loco- motives. Steam carriages for use on railroads, or locomotives, came into public notice subse- quently to the introduction of steam carriages on the common road, but they soon displaced the latter, and have now become the most usual means of transportation. In 1802 Trevi- thick, a Cornish miner, patented a high -pres- sure locomotive with a fly wheel on the crank shaft. Draught was secured by means of bel- lows. This little engine was so powerful that the inventor found the adhesion of the driving wheels to the rails insufficient, antl proposed the use of gearing which should engage a rack laid down between the rails. ' Blenkinsop pur- sued Trevithick's plans, and made a locomotive which ran 10 m. an hour. Blackett in 1812 made a better distribution of weight, and ob- tained ample adhesion. John Stevens of Ho- boken, K J., in 1812 memorialized the legis- lature of the state of New York, urging the building of railways, and showing their advan- tages. He published a pamphlet in which he predicted that trains of carriages would be drawn on railways at 20 or 30 m. an hour, and that they might attain 40 or 50 m. an hour ; and he further says : "I can see nothing to hinder a steam carriage from moving on these ways (rails) with a velocity of 100 m. an hour." Subsequently Stevens applied his steam boiler, patented in 1805, to a locomotive, which was