LITMIR.BIZ

Скачать книгу

locomotive. In the meantime Col. John Stevens of New Jersey was also at work on a steamboat, and had in 1804 built such a boat at his shops, having a screw propeller and a flue boiler. Almost simultaneously with Fulton he brought out the Phœnix, a side-wheel steamer having hollow water lines and provided with feathering paddle wheels, and as Fulton and Livingston had a monopoly of the Hudson, Stevens took his boat by sea from New York around to Delaware bay and up the Delaware river. This was in 1808, and was the first sea voyage ever made by a steam vessel.

      Transatlantic steamship navigation was started in 1819. A Mr. Scarborough of Savannah, Ga., in 1818 purchased a ship of about three hundred and fifty tons burden, which was named the Savannah. Equipped with engine and machinery it steamed out of New York Harbour on the 27th day of March, 1819, and successfully reached Savannah, Georgia. On the 20th of May in the same year she left Savannah for Liverpool, making the trip in 22 days. From Liverpool she went to Copenhagen, Stockholm, St. Petersburg, Cronstadt and Arundel, and from the latter port returned to Savannah, making the passage in twenty-five days.

      But Scottish waters, and the waters around other coasts of the British Islands, had been traversed by steamboats before this celebrated trip of the Savannah. Bell's steamboat between Glasgow and Greenock in 1812 was followed by five others in 1814; and seven steamboats plied on the Thames in 1817.

      So the locomotives and the steamboats and steamships continued to multiply, and when the first forty years of the century had been reached the Iron Horse was fairly installed on the fields of Europe and America, and the rivers and the oceans were ploughed by its sisters, the steam vessels.

      It was in 1840 that the famous Cunard line of transatlantic steamers was established, soon followed by the Collins line and others.

      A few years before, John C. Stevens in America and John Ericsson in England had brought forward the screw propeller; and Ericsson was the first to couple the engine to the propeller shaft. It succeeded the successful paddle wheels of Fulton in America and Bell in England.

      The nineteenth century is the age of kinetic energy: the energy of either solid, liquid, gaseous or electrical matter transformed into useful work.

      It has been stated by that eminent specialist in steam engineering, Prof. R. H. Thurston, that "the steam engine is a machine which is especially designed to transform energy originally dormant or potential into active and useful available kinetic energy;" and that the great problem in this branch of science is "to construct a machine which shall in the most perfect manner possible convert the kinetic energy of heat into mechanical power, the heat being derived from the combustion of fuel, and steam being the receiver and conveyor of that heat."

      Watt and his contemporaries regarded heat as a material substance called "Phlogiston." The modern kinetic theory of heat was a subsequent discovery, as elsewhere explained.

      The inventors of the last part of the eighteenth century and of the nineteenth century have directed their best labours to construct an engine as above defined by Thurston.

      First as to the boiler: Efforts were made first to get away from the little old spherical boiler of Hero. In the 18th century Smeaton devised the horizontal lengthened cylindrical boiler traversed by a flue. Oliver Evans followed with two longitudinal flues. Nathan Read of Salem, Massachusetts, in 1791, invented a tubular boiler in which the flues and gases are conducted through tubes passing through the boiler into the smokestack. Such boilers are adapted for portable stationary engines, locomotives, fire and marine engines, and the fire is built within the boiler frame. Then in the 19th century came the use of sectional boilers – a combination of small vessels instead of a large common one, increasing the strength while diminishing capacity – to obtain high pressure of steam. Then came improved weighted and other safety valves to regulate and control this pressure. The compound or double cylinder high-pressure engine of Hornblower of England, in 1781, and the high-pressure non-condensing steam engine devised by Evans in 1779, were reconstructed and improved in the early part of the century.

      To give perfect motion and the slightest friction to the piston; to regulate the supply of steam to the engine by proper valves; to determine such supply by many varieties of governors and thus control the speed; to devise valve gear which distributes the steam through its cycles of motion by which to admit the steam alternately to each end of the steam cylinder as the piston moves backward and forward, and exhaust valves to open and close the parts through which the steam escapes; to automatically operate such valves; to condense the escaping steam and to remove the water of condensation; to devise powerful steam brakes – these are some of the important details on which inventors have exercised their keenest wits. Then again the extensive inventions of the century have given rise to a great classification to designate their forms or their uses: condensing and non-condensing, high-pressure or low-pressure – the former term being applied to engines supplied with steam of 50 lbs. pressure to the square inch and upward, and the latter to engines working under 40 lbs. pressure – and the low pressure are nearly always the condensing and the high pressure the non-condensing; reciprocating and rotary – the latter having a piston attached to a shaft and revolving within a cylinder of which the axis is parallel with the axis of rotation of the piston.

      Direct acting, where the piston rod acts directly upon the connecting rod and through it upon the crank, without the intervention of a beam or lever; oscillating, in which the piston rods are attached directly to the crank pin and as the crank revolves the cylinder oscillates upon trunnions, one on each side of it, through which the steam enters and leaves the steam chest.

      Then as to their use, engines are known as stationary, pumping, portable, locomotive or marine.

      The best-known engine of the stationary kind is the Corliss, which is very extensively used in the United States and Europe.

      Among other later improvements is the duplex pumping engine, in which one engine controls the valve of the other; compensating devices for steam pumping, by which power is accumulated by making the first half of the stroke of the steam piston assist in moving the piston the other half of the stroke during the expansion of steam; steam or air hand hammers on which the piston is the hammer and strikes a tool projecting through the head into the cylinder; rock drilling, in which the movement of the valves is operated by the piston at any portion of its stroke; shaft governors, in which the eccentric for operating the engine valves is moved around or across the main or auxiliary shaft; multiple cylinders, in which several cylinders, either single or double, are arranged to co-operate with a common shaft; impact rotary, known as steam turbines, a revival in some respects of Hero's engine. And then, finally, the delicate and ingenious bicycle and automobile steam engines.

      Then there are steam sanding devices for locomotives by which sand is automatically fed to the rails at the same time the air brake is applied.

      Starting valves used for starting compound locomotives on ascending steep grades, in which both low and high pressure cylinders are supplied with live steam, and when the steam, exhausted from either high or low pressure cylinders into the receivers, has reached a predetermined pressure, the engine works on the compound principle. Single acting compound engines, in which two or more cylinders are arranged tandem, the steam acting only in one direction, and the exhaust steam of one acting upon the piston in the cylinder next of the series, are arranged in pairs, so that while one is acting downward the other is acting upward.

      Throttle valves automatically closed upon the bursting of a pipe, or the breaking of machinery, are operated by electricity, automatically, or by hand at a distance.

      Napoleon, upon his disastrous retreat from Moscow, anxious to reach Paris as soon as possible, left his army on the way, provided himself with a travelling and sleeping carriage, and with relays of fresh horses at different points managed, by extraordinary strenuous efforts day and night, to travel from Smorgoni to Paris, a distance of 1000 miles, between the 5th and 10th of December, 1812. This was at the average rate of about two hundred miles a day, or eight or nine miles an hour. It was a most remarkable ride for any age by horse conveyance.

      Within the span of a man's life after that event any one could take a trip of that distance in twenty-four hours, with great ease and comfort, eating and sleeping on the car, and with convenient telegraph and telephone stations along the route by which to comunicate by pen, or word of mouth, with distant friends at either

Скачать книгу