The honour of being the first British steam iron warship belongs to the _Trident_, a paddle-steamer, launched from Ditchburn and Mare’s shipbuilding yard at Blackwall in December 1845. Her length was 280 feet, the length of engine-room 45 feet, her beam 31 feet 6 inches, her breadth over paddles 52 feet 6 inches, her depth of hold 18 feet, and she was of 900 tons burden, including machinery, coals, water, guns, and stores. Her displacement at launching was 385 tons; the engines of 330 horse-power had oscillating cylinders, and her boilers were of a tubular pattern. She was designed by the builders. Her ribs were double, each rib being composed of two angle irons 4 inches by 3¹⁄₂ inches by half an inch thick, riveted together, and in one entire length from the gunwale to the keel, there being 270 pairs of these double ribs. The iron skin was three-quarters of an inch thick at the keel, and half an inch at the gunwale. The skin contained 1400 plates of iron which were riveted to each other and to the ribs and the keel by 200,000 rivets. Each rivet was wrought red-hot and required the united labours of three workmen and two boys to fix it in its corresponding hole. The price of iron when the ship was commenced was £8 10_s._ per ton, and when it was launched £16. The _Trident_ carried two long swivel guns of 10-inch bore, one forward and one aft, to fire in line with the keel, and had also four 32-pounder broadside guns. The _Greenock_, built by Scott, Sinclair and Co. at Greenock in 1849, was a second-class steam frigate and was the first steam frigate ever launched on the Clyde for the British Navy. Her length was 213 feet and her tonnage 1413 tons Admiralty measurement, with engines of 565 horse-power by the same builders. The screw propeller was 14 feet in diameter, constructed on F. P. Smith’s principle, and though it weighed seven tons, could be disengaged from the machinery and raised from the sea with ease. “The funnel also is to have some peculiar mode by which its hideous and crater-like physiognomy can be made at once to disappear, and leave the ship devoid at once of this unsightly feature, and of those cumbrous excrescences, paddle-boxes, giving her all the appearance and symmetry of a perfect sailing ship.”[96] Her figure-head was a bust of the late Mr. John Scott, father of the head of the firm who built her. The keel, stem, and stern were of solid malleable iron, measuring 5 inches thick by 9 inches deep. The _Greenock_ was the only one of four vessels ordered by the then Board of Admiralty, to be fitted as a frigate and propelled with full power. She was armed on the main deck, and her model was so designed as to enable her to fight her bow and stern guns in line with the keel, in which important qualification she stood almost alone in the Navy. [96] _Illustrated London News_, May 12, 1849. The value of private shipbuilding yards able to undertake Admiralty work at short notice was abundantly proved during the Crimean War.