To the close of his life Watt continued to take great pleasure in inventing. It had been the pursuit of his life, and in old age it became his hobby. “Without a hobby-horse,” said he, “what is life?” He proceeded to verify his old experiments, and to live over again the history of his inventions. When Mr. Kennedy of Manchester asked him, at one of his last visits to Heathfield, if he had been able, since his retirement from business, to discover anything new in the steam-engine, he replied, “No; I am devoting the remainder of my life to perfect its details, and to ascertain whether in any respect I have been wrong.”
But he did not merely confine himself to verifying his old inventions. He also contrived new ones. One of the machines that occupied his leisure hours for many years, was his machine for copying statuary. We find him busy with it in 1810, and he was still working upon it in the year of his death, nearly ten years later. The principle of the machine was to make a cutting tool or drill travel over the work to be executed, in like ratio with the motion of a guide-point placed upon the bust to be copied. It worked, as it were, with two hands; the one feeling the pattern, the other cutting the material into the required form. The object could be copied either of the full size, or reduced with the most perfect accuracy to any less size that might be required.[416] In preparing the necessary tools, Watt had the able assistance of his friend Murdock, who was always ready with his kindly suggestions and criticisms. In January, 1813, Watt wrote him,—“I have done a little figure of a boy lying down and holding out one arm, very successfully; and another boy, about six inches high, naked, and holding out both his hands, his legs also being separate. But I have been principally employed in making drawings for a complete machine, all in iron, which has been a very serious job, as invention goes on very slowly with me now. When you come home, I shall thank you for your criticisms and assistance.”[417]
The material in which Watt executed his copies of statuary were various,—marble, jet, alabaster, ivory, plaster of Paris, and mahogany. Some of the specimens we have seen at Heathfield are of exquisite accuracy and finish, and show that he must have brought his copying-machine to a remarkable degree of perfection before he died. There are numerous copies of medallions of his friends,—of Dr. Black, De Luc, and Dr. Priestley; but the finest of all is a reduced bust of himself, being an exact copy of Chantrey’s original plaster-cast. The head and neck are beautifully finished, but there the work has stopped, for the upper part of the chest is still in the rough. Another exquisite work, than which Watt never executed a finer, is a medallion of Locke in ivory, marked “January, 1812.” There are numerous other busts, statuettes, medallions,—some finished, others half executed, and apparently thrown aside, as if the workman had been dissatisfied with his work, and waited, perhaps, until he had introduced some new improvement in his machine.
Watt took out no patent for the invention, which he pursued, as he said, merely as “a mental and bodily exercise.” Neither did he publish it,—but went on working at it for several years before his intentions to construct such a machine had become known. When he had made considerable progress with it, he learned, to his surprise, that a Mr. Hawkins, an ingenious person in his neighbourhood, had been long occupied in the same pursuit. The proposal was then made to him that the two inventors should combine their talents and secure the invention by taking out a joint patent. But Watt had already been too much worried by patents to venture on taking out another at his advanced age. He preferred prosecuting the invention at his leisure merely as an amusement; and the project of taking out a patent for it was accordingly abandoned. It may not be generally known that this ingenious invention of Watt has since been revived and applied with sundry modifications by our cousins across the Atlantic, in fashioning wood and iron in various forms; and powerful copying-machines are now in regular use in the Government works at Enfield, where they are employed in rapidly, accurately, and cheaply manufacturing gun-stocks!
Watt carried on the operations connected with this invention for the most part in his Garret, a room immediately under the roof at the kitchen end of the house at Heathfield, and approached by a narrow staircase. It is a small room, low in the ceiling, and lighted by a low broad window, looking into the shrubbery. The ceiling, though low, inclines with the slope of the roof on three sides of the room, and, being close to the slates, the place must necessarily have been very hot in summer, and very cold in winter. A stove was placed close to the door, for the purpose of warming the apartment, as well as enabling the occupant to pursue his experiments, being fitted with a sand-bath and other conveniences. But the stove must have been insufficient for heating the garret in very cold weather, and hence we find him occasionally informing his correspondents that he could not proceed further with his machine until the weather had become milder.
WATT’S GARRET AT HEATHFIELD.
[By Percival Skelton.]
His foot-lathe was fixed close to the window, fitted with all the appliances for turning in wood and metal fifty years since; while a case of drawers fitted into the recess on the left-hand side of the room, contained a large assortment of screws, punches, cutters, taps, and dies. Here were neatly arranged and stowed away many of the tools with which he worked in the early part of his life, one of the drawers being devoted to his old “flute tools.” In other divisions were placed his compasses, dividers, scales, decimal weights, quadrant glasses, and a large assortment of instrument-making tools. A ladle for melting lead, and a soldering-iron were hung ready for use near the stove.
Crucibles of metal and stone were ranged on the shelves along the opposite side of the room, which also contained a large assortment of bottles filled with chemicals, boxes of fossils and minerals, jars, gallipots, blowpipes, retorts, and the various articles used in chemical analysis. In one corner of the room was a potter’s lathe. A writing-desk was placed as close to the window, for the sake of the light, as the turning-lathe would allow; and in the corner was the letter-copying machine, conveniently at hand.