In after days Murdoch was able to assist Watt in many of his problems, and to enrich the firm with many of his own inventions. He became a partner in the works along with the sons of Boulton and Watt. He deserves particularly the world’s honour for being the first to discover how to apply coal gas for the purposes of lighting. He illustrated his discovery by the illumination of the Soho works in 1802. For this alone he ought to be gratefully remembered in all the cities where rows of shining lamps give safety to moving multitudes, and in all the homes that have been made brighter and more comfortable by this wondrous illuminant.

Boulton and Watt had to spend so much at first upon the improvements of their engine, and upon the extension of their premises, that it was not till 1783 that profits began to come in. They therefore had their patent extended till the year 1800. They also received other patents for improvements in its structure. Among these was the contrivance for rotatory motion by means of what was called the sun and planet wheels, the expansive principle of working steam, the parallel motion, the smokeless furnace, and the governor. Watt was also the inventor of the well-known copying press, and of many other useful instruments. He was ever meditating upon some mode by which the power of man could be increased and his labour economised. Inventing was a habit which he could not restrain. Wealth flowed in upon the partners, and their works became famous over the whole world. In the year 1800, when their patent expired, Watt wisely withdrew from the business, leaving his shares to his two sons. He was now sixty-four years of age. Since early life he had been oppressed with nervous headaches, and was glad of the release. Never was dream of poet more fully realised. The busy worried life gave place to a prolonged and sweet old age. The cloud which had so long hung over him was gently lifted up, and the curtain parted to disclose a happier scene. It is unusual that even physical ease and enjoyment should come so late, but so it was. The term which commenced with his release from the coils of active business was a serene and golden time, in which he found repose, honour, troops of friends, and the pleasing retrospect of a struggle past and a victory won.

Even in retirement he pursued his old studies. Before this he had acquired Heathfield House, in the fitting up and adornment of which he took great interest. He had the garret converted into a workshop, in which he spent much of his time. There was a foot lathe, and drawers, with screws, pincers, cutters, taps and dies. In other places were compasses, dividers, scales, and quadrants. Here were also the tools-with which he had worked in the early part of his life. In one of the drawers was his old flute. A writing-desk was placed close to the window, and near it his letter copying machine. In this suburban study and workshop he spent many hours meditating and experimenting. One of his last inventions was a sculpture copying machine, the secret of which died with him. He took great pleasure in presenting specimens of his work to his intimate friends, jocularly describing them as the productions of “a young artist just entering his eighty-third year.” Here, too, he prepared the plan for the Old Glasgow Water Works by which water could be conveyed across the Clyde. Dr. Smiles, who visited the room in 1864, found there also a hair trunk, the touching memorial of his son Gregory,