Mr. Marshall was at that time engaged in improving the method of manufacture,[2] and the young blacksmith was so fortunate or rather so dexterous as to be able to suggest several improvements in the machinery which secured the approval of his employer, who made him a present of 20L., and very shortly promoted him to be the first mechanic in the workshop. On this stroke of good fortune Murray took a house at the neighbouring village of Beeston, sent to Stockton for his wife, who speedily joined him, and he now felt himself fairly started in the world. He remained with Mr. Marshall for about twelve years, during which he introduced numerous improvements in the machinery for spinning flax, and obtained the reputation of being a first-rate mechanic. This induced Mr. James Fenton and Mr. David Wood to offer to join him in the establishment of an engineering and machine-making factory at Leeds; which he agreed to, and operations were commenced at Holbeck in the year 1795. As Mr. Murray had obtained considerable practical knowledge of the steam-engine while working at Mr. Marshall's, he took principal charge of the engine-building department, while his partner Wood directed the machine-making. In the branch of engine-building Mr. Murray very shortly established a high reputation, treading close upon the heels of Boulton and Watt--so close, indeed, that that firm became very jealous of him, and purchased a large piece of ground close to his works with the object of preventing their extension.[3] His additions to the steam-engine were of great practical value, one of which, the self-acting apparatus attached to the boiler for the purpose of regulating the intensity of fire under it, and consequently the production of steam, is still in general use. This was invented by him as early as 1799. He also subsequently invented the D slide valve, or at least greatly improved it, while he added to the power of the air-pump, and gave a new arrangement to the other parts, with a view to the simplification of the powers of the engine. To make the D valve work efficiently, it was found necessary to form two perfectly plane surfaces, to produce which he invented his planing machine. He was also the first to adopt the practice of placing the piston in a horizontal position in the common condensing engine. Among his other modifications in the steam-engine, was his improvement of the locomotive as invented by Trevithick; and it ought to be remembered to his honour that he made the first locomotive that regularly worked upon any railway. This was the engine erected by him for Blenkinsop, to work the Middleton colliery railway near Leeds, on which it began to run in 1812, and continued in regular use for many years. In this engine he introduced the double cylinder--Trevithick's engine being provided with only one cylinder, the defects of which were supplemented by the addition of a fly-wheel to carry the crank over the dead points.