STEAM

The idea of steam-jet propulsion had been suggested by the Greek mathematician Hero as long ago as the 1st century A.D.

		The earliest form of Marine Engine seems to have been devised by Patrick Miller of Dalswinton, and constructed in Edinburgh (1788) by William Symington. Its cylinders were 4 inches in diameter, and it was able to drive a pleasure-boat 25 feet long, with two central paddle-wheels, at a speed of 5 miles an hour. Subsequently Symington constructed (1801) an engine on Watt's double-acting principle, and with a stern-wheel, which was used on a canal in Scotland, in a steamboat called the Charlotte Dundas.
The Charlotte Dundas - the first Scotish paddle steamer 1801-02		This engine was seen by Robert Fulton, who employed (1807) an English firm to build a similar engine for a steamer called the Clermont, which he afterwards successfully employed upon the Hudson river in America.

Henry Bell, the first successful applier of steam to the purposes of navigation in Europe, was born in Linlithgowshire 1767, died at Helensburgh 1830. He was apprenticed as a millwright, and afterwards served under several engineers, including Rennie. He settled in Glasgow in 1790, and subsequently in Helensburgh. In 1798 he turned his attention specially to the steam-boat, the practicability of steam navigation having been already demonstrated.

In 1812 the Comet, a small thirty-ton vessel built at Port-Glasgow by John Wood under Bell's directions, and commenced to ply between Glasgow and Greenock. The Comet, which had side paddle-wheels and was about 42 feet long and 11 feet wide, was driven by a kind of inverted beam-engine, with a single vertical cylinder, developing four or five horse-power, and continued to run till she was wrecked in 1820. This was the beginning of steam navigation in Europe. It has been asserted that Fulton, who started a steamer on the Hudson in 1807, obtained his ideas from Bell in the previous year.

Bell is also credited with the invention of the 'discharging machine' used by calico-printers. A monument has been erected to his memory at Dunglass Point on the Clyde.

These early marine engines were constructed in a maner similar to James Watt's land engine, but the position of the beam so high above the deck was soon recognized as a defect, especially in sea-going steamers. Instead, therefore, of a beam placed above the cylinder and piston, two beams or levers were placed below, one on each side of the engine, and the connecting-rod conveyed the power to the crank upwards instead of downwards. This design, however, was soon afterwards discarded in favour of an arrangement by which the cylinder was placed beneath and connected directly with the crank. A further improvement was secured by an oscillating cylinder, which moved right and left with the swing of the crank and enabled the piston-rods to be connected directly with the cranks.

		Trevithick had produced a 'whirling engine' in 1814 which consisted essentially of two hollow arms mounted on a shaft. Steam escaped at a tangent from small holes at the end of each arm, whirling them round. The maximum of 250 rpm, however, represented only about a fifth of the potential power of the steam used.When the paddle-wheel was superseded by the screw-propeller a totally different typo of marine engine was required.
The Savannah - the first Steam assisted crossing of the Atlantic (1819)		In this case the cylinder was inverted and placed above the shaft of the screw near the deck, and the connection with the crank was formed by means of an ordinary connecting-rod.

The use of iron and steel in the construction of ships provided Britain, with a ship-building industry. Formerly ships were constucted at the port. where suitable timber was most accessible, but now they could be found chiefly at those where the coal and the iron are near-by, thus the Clyde, the Tyne, and the Wear become the principal centres of ship-building.

Isambard Kingdom Brunel, designed the entire work on the Great Western Railway, to which he was appointed engineer in 1833. In 1836 the Railway Company set up the "Great Western Steamship Company", and Brunel, designed the Great Western, which set sail for New York City on April 8, 1838. She was propelled by paddles, but about the same time Ericsson invented his screw-propeller, which was soon adopted in sea-going ships, and the British Admiralty possessed a screw vessel in 1842.

It was Cunard's steamboat company, that won the British government contract to establish a mail line across the North Atlantic. The largest vessels were propelled by steam, but very large sailing vessels were constructed also, especially since it became not uncommon to fit them with four, and even five mast. In 1840 the Cunard Line launched four paddle steamers with auxiliary sails - the Britannia, Acadia, Columbia, and Caledonia - Many of the vessels belonging to the great ocean lines were splendid specimens of naval architecture, some of them being 600 feet in length, having a capacity of 10,000 or 12,000 tons or even more, and with engines working up to 20,000 or 30,000 horse-power.

The first ocean-going steamship, with an all-iron hull, and propelled by the screw, was Brunel's second ship the Great Britain, launched in 1843 (it now survives in Bristol's Floating Dock). He also designed the largest ship of the century, which was launched in 1858, the Great Eastern. It combined iron construction, steam power and both paddle and screw propulsion. It was not a success, requiring much higher coal consumption than had been anticipated.

Among early steel ships built were those by the Confederates in the American Civil War as fast blockade-runners, and so the progress of navigation is marked by special types of vessels built from time to time.

The first steam warship was constructed in 1814, between 1841 and 1859 steam was gradually substituted for the sailing vessels in the British navy.

		In ships-of-war a horizontal direct-acting engine was adopted in order to keep the machinery below the water-line and out of danger from the enemy's guns. This took various forms, such as Penn's trunk-engine, where compactness was obtained by securing the connecting-rod directly to the piston and using the piston-rod as a hollow trunk within which the connecting-rod could oscillate freely and the engine designed by Maudsley, in which two piston-rods proceed from each piston, and the connecting-rod is reversed so as to embrace the crank on the screw-shaft, near which the cylinder is placed.
The Sirus - the first continuous steam power crossing 18½ days (1838)		However, there was a tendency in war-ships to adopt the inverted vertical direct-acting engine as used in nearly all the large ocean steamers-

Compound engines (first introduced by Messrs. Randolph, Elder, & Ca of Glasgow, in 1854), with high-pressure steam, were not used in the Royal Navy till 1867 (in the Sirius). These engines were commonly constructed with a two - cylinder compound arrangement.After 1854 ships began to be armour-plated, and since 1860 armour-plated ships, armed with guns of enormous calibre, were substituted for timber vessels, but this had been preceded by a vessel of like build launched by France in the previous year. Guns were, however, quickly invented which could pierce the armour carried by these vessels, and so later ships had a greater thickness of armour, and carried guns which were powerful enough to pierce the armour of the opposing vessels.

The ordinary ironclad was about the year 1862 superseded by the turret ship, and under the direction of Sir E. T. Reed, the constructor of the Navy, a ship was produced which was capable of firing in all directions from central batteries, and did not depend entirely upon its broadsides. Turret and mastless warships were now regarded as the latest thing in naval construction, and the turrets carried an armour-plating of from 10 to 14 inches thick.

In 1874 Mr. A. C. Kirkbut first designed a three-crank triple-expansion engine. This form of marine steam - engine was found to effect a considerable saving in fuel, and the principle of expanding the steam was even been used in a four-cylinder quadruple-expansion engine with success.

After 1880 Great Britain began a programme of naval construction, from this developed the race in naval armaments. When H.M.S.Dread Nought was launched 1906 equipped with 12" guns with a speed of over 20 knots and a range of over 32 km (20 miles) it was the most formidable fighting ship in the world. From 1898 the German government began to reduce the enormous gap between British and German naval power, building Dreadnought-type battleships, and constructing a number of the new (Unterseebooten) U-boats.

STEAM TURBINES

The modem steam turbine was developed by the British engineer Charles Parsons who combined high efficiency with a high rate of rotation by passing the steam through a series of small turbines, dividing the fall of pressure as the steam expanded into a number of stages. Each turbine consisted of a fixed cylinder called the stator with stationary blades on the inner surface and a central rotor with similar blades. Steam passed through the stator parallel to the shaft and alternately between the two sets of blades, rotating the shaft. In 1884, the first steam turbine was used to generate electricity and ran at 18,000 rpm. Three years later, Parsons introduced a compound turbine with high and low pressure stages. Development of the turbine was rapid. although the basic design remained almost unchanged, by the end of the century, his twin cylinder turbine was generating 2,000 k.w for the German town of Elberfeld. Parson's first attempt in 1894 to develop a steam turbine marine engine failed because the high rate of rotation could not provide the screw propeller with the necessary thrust.

In 1896, he tried a system with three shafts each carrying three screws driven by a connected series of turbines. There was also a separate turbine driving the central shaft for reversing. The engines of his ship, the Turbinia, developed 2,000 hp, and when she first appeared at the Jubilee Navy Spithead Review in 1897, she reached the unheard-of speed of 34½ knots. Later systems included reduction gearing so that the engine could run at its most efficient and highest speed, while the screw propeller had reduced revolutions for maximum thrust.

The turret ships were in the course of time replaced by ships of the cruiser type. These were armoured and protected, and were speedier than the ordinary line-of-battle ships, but did not carry so much armour-plating and thus were not so well protected.