Chap. VIII.

BRITAIN.

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the steam in a separate vessel; removing the air and water from the condenser by an air-pump ; producing the movement by the aid of steam instead of atmospheric pressure;giving the piston an impulse or moving power both in ascending and descending ; con-verting the alternate rectilinear motion of the piston into a continued circular motion, soas to adapt the engine for impelling machinery, and working the steam expansively, andthus greatly economising the fuel: this important engine, as completed by these and otherimprovements, soon superseded all other inventions of the kind, the principles which he esta-blished being those in use throughout the world at the present day. His first work is knownas the single-acting steam-engine, in contradistinction to the double-acting engine, as it wasafterwards called, in consequence of that beautiful arrangement which allowed the steamto enter alternately above and below the piston, at the same time forming the vacuumalternately, by which a moving force was communicated to the piston in its ascent as wellas in its descent; thus constituting a continuous moving power.

To the genius and sagacity of Janies Watt the whole world owes a debt of gratitude;and Dr. Darwin, in his “ Botanic Garden,” has well asked, “ Why, if at Rome a civiccrown was given to him who saved the life of a single citizen, is not the projector of thesteam-engine considered worthy of being covered with garlands of oak?”

Steamboat Engine. — About the year 1736, Jonathan Hulls took out a patent for “anew-invented machine for conveying vessels or ships out of or into any harbour, port, orriver, against wind or tide, or in a calm.” The power was procured by the pressure ofthe atmosphere against a vacuum, and, by some curious machinery, motion was given to apaddle-wheel, the continued rotation of which was provided for. This was probably thefirst attempt to apply the power of steam to navigation, and which has led to vessels sopropelled crossing the Atlantic Ocean, and making the voyage to India .

In the year 1775, M. Perier had a small steamboat on the Seine , and seven or eightyears afterwards the Marquis of Jouffray constructed one at Lyons, HO feet in length,and 15 feet in width, which navigated the Saone for some time: about the same periodthey were introduced into Scotland as canal boats, and on the Forth and Clyde canal therewas one which plied with much success. But it was not until Mr. Fulton, an American,had studied the subject, that a really efficient vessel was built; in the year 1807 helaunched one at New York, containing an engine made by Bolton and Watt for thepurpose, and a voyage was performed between that city and Albany, a distance of 160miles, in thirty hours.

After Fulton had shown that steam might be applied as a moving power to ships,numerous other attempts were speedily made, and the first steamboat in Europe , after theappearance of Fulton’s, was “ The Comet,” which plied between Glasgow and Greenock .

“ The Great Western,” built expressly to cross the Atlantic, had two engines, each of225 horse-power; her burthen 1340 tons; her paddle-wheels made 273,000 revolutions;her consumption of coal was 1£ tons per hour. “ Hie British Queen,” of 1862 tons, sinceemployed in the Atlantic navigation, had the diameter of the paddle-wheels 30 feet, and thepower of her engine was 500 horse.

These large vessels usually make the voyage from Falmouth to New York in seventeenor eighteen days, their least speed being 89 miles per day; and the average for the wholevoyage has been 190 miles daily.

Locomotive Engines _After the great improvements made in the steam-engine by Mr.

James Watt , those of high-pressure ceased to be generally used by manufacturers; butin the patent obtained in the year 1784, he explains that his newly-invented engine wascalculated to propel carriages; and the manner by which he proposed to effect this was, byhaving a boiler made of wood, like a cask, to contain in the inside an iron furnace, whichwas to be entirely surrounded by water: this simple apparatus was to be placed on a car-riage, and the wheels worked by means of a piston, the reciprocating motion being convertedinto a rotary one by toothed wheels and a sun and planet motion. Hie wheels differed intheir proportions, in order that the variable resistance offered by the road might be moreeasily overcome. The cylinder was to be 7 inches in diameter, the length of thestroke 12 inches, and the number per minute 60. This carriage was to carry two persons,but it was never executed, as the inventor always manifested an objection to high-pressuresteam.

In the year 1802, a patent was taken out by Richard Trevithick for a locomotive car-riage ; this was the first attempt to adapt the power either to the common road or arailroad, and its principle was high-pressure. The carriage had two small wheels in front,which served the purpose of guiding it, and two larger ones behind, by which it was driven.The cylinder, boiler, and fire were all enclosed in a case, and placed low down in the rearof the axle, and the large wheels could either be worked together or singly, or one couldgo one way whilst the other moved in an opposite direction; their motion was produced bya spur-gear, which had a fly-wheel added to it. The piston rod, outside the cylinder, wasdouble, and drove a cross piece, working in guides on the opposite side of the crankedaxle to the cylinder, and the crank of the axle revolved between the double parts of the

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