HKB
When he came out of the engine-house, the miners cheered him vociferously and insisted upon carrying him home upon their shoulders in triumph!
Steam was now asserting its power everywhere. It was pumping water from the mines in Cornwall and driving the mills of the manufacturers in Lancashire. Speculative mechanics began to consider whether it might not be employed as a means of land locomotion. The comprehensive mind of Sir Isaac Newton had long before, in his 'Explanation of the Newtonian Philosophy,' thrown out the idea of employing steam for this purpose; but no practical experiment was made. Benjamin Franklin, while agent in London for the United Provinces of America, had a correspondence with Matthew Boulton, of Birmingham, and Dr. Darwin, of Lichfield, on the same subject. Boulton sent a model of a fire-engine to London for Franklin's inspection; but Franklin was too much occupied at the time by grave political questions to pursue the subject further. Erasmus Darwin's speculative mind was inflamed by the idea of a "fiery chariot," and he urged his friend Boulton to prosecute the contrivance of the necessary steam machinery.[6]
Other minds were at work. Watt, when only twenty-three years old, at the instigation of his friend Robison, made a model locomotive, provided with two cylinders of tin plate; but the project was laid aside, and was never again taken up by the inventor. Yet, in his patent of 1784, Watt included an arrangement by means of which steam-power might be employed for the purposes of locomotion. But no further model of the contrivance was made.
Meanwhile, Cugnot, of Paris, had already made a road engine worked by steam power. It was first tried at the Arsenal in 1769; and, being set in motion, it ran against a stone wall in its way and threw it down. The engine was afterwards tried in the streets of Paris. In one of the experiments it fell over with a crash, and was thenceforward locked up in the Arsenal to prevent its doing further mischief. This first locomotive is now to be seen at the Conservatoire des Arts et Metiers at Paris.
Murdock had doubtless heard of Watt's original speculations, and proceeded, while at Redruth, during his leisure hours, to construct a model locomotive after a design of his own. This model was of small dimensions, standing little more than a foot and a half high, though it was sufficiently large to demonstrate the soundness of the principle on which it was constructed. It was supported on three wheels, and carried a small copper boiler, heated by a spirit lamp, with a flue passing obliquely through it. The cylinder, of 3/4 inch diameter and 2-inch stroke, was fixed in the top of the boiler, the piston-rod being connected with the vibratory beam attached to the connecting-rod which worked the crank of the driving-wheel. This little engine worked by the expansive force of steam only, which was discharged into the atmosphere after it had done its work of alternately raising and depressing the piston in the cylinder.
Mr. Murdock's son, while living at Handsworth, informed the present writer that this model was invented and constructed in 1781; but, after perusing the correspondence of Boulton and Watt, we infer that it was not ready for trial until 1784. The first experiment was made in Murdock's own house at Redruth, when the little engine successfully hauled a model waggon round the room,--the single wheel, placed in front of the engine and working in a swivel frame, enabling it to run round in a circle.