THE GOVERNOR.
Another of Watt’s beautiful inventions of the same period, was the Governor, contrived for the purpose of regulating the speed of the engine. This was a point of great importance in all cases where steam-power was employed in processes of manufacture. To modify the speed of the piston in the single-acting pumping-engine, Watt had been accustomed to use what is called a throttle valve, which was regulated by hand as occasion required. But he saw that to ensure perfect uniformity of speed, the action of the engine must be made automatic if possible, and with this object he contrived the Governor, which has received no improvement since it left his hand. Two balls are fixed to the ends of arms connected with the engine by a moveable socket, which plays up and down a vertical rod revolving by a band placed upon the axis or spindle of the fly-wheel. According to the centrifugal force with which the balls revolve, they diverge more or less from the central fixed point, and push up or draw down the moveable collar; which, being connected by a crank with the throttle-valve, thereby regulates with the most perfect precision the passage of the steam between the boiler and the cylinder. When the pressure of steam is great, and the tendency of the engine is to go faster, the governor shuts off the steam; and when it is less, the governor opens the throttle-valve and increases the supply. By this simple and elegant contrivance the engine is made to regulate its own speed with the most beautiful precision.
Among the numerous proposed applications of the steam-engine about this time, was its employment as a locomotive in driving wheel-carriages. It will be remembered that Watt’s friend Robison had, at a very early period, directed his attention to the subject; and the idea had since been revived by Mr. Edgeworth, who laboured with great zeal to indoctrinate Watt with his views. The latter, though he had but little faith in the project, nevertheless included a plan of a locomotive engine in his patent of 1784; but he took no steps to put it in execution, being too much engrossed with other business at the time. His plan contemplated the employment of steam either in the form of high-pressure or low-pressure, working the pistons by the force of steam only, and discharging it into the atmosphere after it had performed its office, or discharging it into an air-tight condenser made of thin plates or pipes, with their outsides exposed to the wind or to an artificial current of air, thereby economising the water which would otherwise be lost.
Watt did not carry his design into effect; and, so far as he was concerned, the question of steam locomotion would have gone no further. But the subject had already attracted the attention of William Murdock, who had for some time been occupied during his leisure hours in constructing an actual working model of a locomotive. When his model was finished, he proceeded to try it in the long avenue leading to the parsonage at Redruth, in the summer of 1784; and in so doing nearly frightened out of his wits the village pastor, who encountered the hissing, fiery little machine, while enjoying his evening walk.[264]
When Watt heard of this experiment, he wrote to Boulton, advising that Murdock should be gently counselled to give up his scheme, which might have the effect of withdrawing him from the work of the firm, in which he had become increasingly useful.
“As to my own part,” wrote Watt, “I shall form no obstacle to the scheme. My only reasons against it were that I feared it would deprive us of a valuable man; that it would, if we were to be concerned in it, divert us from more valuable business, and perhaps prove a sinking fund; and lastly, that I did not like that a scheme which I had revolved in my mind for years and hoped to be able at some favourable time to bring to perfection, if capable of it, should be wrested from me, or that I should be compelled to go into it as a secondary person. But I have now made the latter objection give way. And as to the first, I think it will take place at any rate, so we must make the best of it.”[265]
Boulton was accordingly recommended in the first place to endeavour to dissuade Murdock from pursuing the subject further, but if he could not succeed in that, rather than lose him, he was to let him have an advance to the extent of 100l., to enable him to prosecute his experiments; and if within a year he succeeded in making an engine capable of drawing a postchaise carrying two ordinary persons and the driver, with 200 lbs. of luggage, fuel for four hours, and water for two hours, going at the rate of four miles an hour, then a partnership was to be entered into, in which Boulton and Watt were to find the capital, and Murdock was to conduct the business and take his share of the profits.
Murdock, however, had so many urgent matters to attend to, that, sanguine though he continued to be as to the success of his scheme, he could not find time to pursue it. He was a man after Boulton’s own heart, unsparing of himself and indefatigable in whatsoever he undertook; nor was Boulton sparing of praises of him in his confidential letters to Watt.
“We want more Murdocks,” he wrote on one occasion, “for, of all our men he is the most active. He is the best engine erector I ever saw, and of his energy I had one of the best proofs this day. They stopped Poldice lower engine last Monday and took her all to pieces; took out the condenser, took up out of the shaft the greatest part of the pumps, took the nozzles to pieces, cut out the iron seatings and put in brass ones with new valves, mended the eduction-pipe, and did a great number of repairs about the beam and engine; put the pumps down into the new engine shaft, did much work at the new engine; and this done, about noon both the engines, new and old, were set to work again complete. When I look at the work done it astonishes me, and is entirely owing to the spirit and activity of Murdock, who hath not gone to bed for three nights, and I expect the mine will be in full fork again by Wednesday night. I have got him into good humour again without any coaxing, have prevailed on him not to give up Wheal Virgin engine, which he had been resolved to do from the ungenerous treatment he received from the captains. I have also prevailed on him to put off his determined journey to Scotland until North Downs engines are got to work, and have quieted his mind about wheel carriages till then.”[266]
Notwithstanding Watt’s fears of a falling off, the engine business still continued to prosper in Cornwall. Although the mining interests were suffering from continued depression, new mines were being opened out, for which pumping-engines were wanted; and Boulton and Watt’s continued to maintain their superiority over all others. None of their threatened rivals had yet been able to exhibit an engine in successful work; and those of the old construction had been almost completely superseded. In 1784, new engines were in course of erection at Poldice, New Poldory, Wheal Maid, Polgooth, and other mines. Almost the last of the Newcomen engines in Cornwall had been discarded at Polgooth in favour of one of Boulton and Watt’s 58-inch cylinder engines.