himself involved in pecuniary difficulties, in consequence of the failure of his undertaking in the Borrowstounness coal and iron works, and was unable to supply the necessary funds for the prosecution of the design.

CHAPTER V.

PROCEEDINGS AT THE SOHO WORKS.

HOWEVER disappointed Mr. Watt may have been by the failure of his hopes through the inability of Dr. Roebuck to carry on the projected manufacture of his engines, he was not long left without the assistance he required. His inventions had already become known to many intelligent men engaged in manufactures, and, among others, to Mr. Matthew Bolton, of Soho Works, near Birmingham. This gentleman was at that time carrying on one of the largest and most successful metal trades in England, and was alike distinguished for his business habits and commercial enterprise. In the moment of Watt's perplexity, Bolton made an offer for the purchase of Dr. Roebuck's share in the patents: terms were made, and the agreement was completed. In the early part of the year 1774, Mr. Watt removed to Soho, where a portion of the manufactory was placed under his entire control, for the erection of a foundry, and all other shops and machinery necessary for carrying out his inventions upon the largest scale, and in the most perfect manner.

On a review of the expenses already incurred, and a calculation of those which had to be borne before the engine could be perfected, and the works made suitable for the manufacture, it became evident that an extension of the patentright should if possible be obtained. The patent had been granted in 1769 for a period of fourteen years, and would therefore terminate in 1783, so that the remaining term was too short a period to give security for the return of the large capital to be invested in the undertaking. In consideration of the risk, and of the labor and skill yet to be expended, an application was made to parliament for a lengthened period of protection, and, in 1775, an act was passed extending the patent to the year 1800.

Those who know any thing of the construction of machinery are well aware that, after the most careful and minute examination of a new design, alterations and improvements are frequently suggested in the progress of manufacture; and they can easily understand how numerous and varied these must have been in the early history of the steam-engine. The comparatively low state of mechanical art, the necessity of proving every invention and application, and of designing new tools for the construction or performance of the work required, were not the only impediments Mr. Watt had to overcome. He had the still more difficult task of teaching others how to execute what he designed. He was not, like the engineer of the present day, surrounded by men educated to their trade, neither asking nor

needing more than a drawing of what is required. He introduced a new engine, and with it a new style of work: precision and minute accuracy were indispensable, and prejudices were to be overcome; confidence, too, was to be inspiredthat strange feeling of reliance on a superior mind which must exist between a superintendent and his workmen to secure respect, obedience, and promptitude. To all this the great mechanist was equal, though his health suffered from his exertions. "I have been," he says, in a letter to Smeaton, dated April, 1766, "tormented with exceedingly bad health, resulting from the operation of an anxious mind, the natural conscquence of staking every thing upon the cast of a die; for in that light I look upon every project which has not received the sanction of repeated success."

The engine first constructed at Soho, afterwards known as the single-action engine, was in principle the same as that already described, but much improved in its details. Every experiment made a demand for greater accuracy. The mechanist was now for the first time bringing under control one of the most subtle agencies of nature. Previous mechanicians had been able to forge and form hard inflexible bodies to their purpose: they had commanded and directed the flowing water, and from its motion obtained forces acting in power and direction according to their will: the air which came and went without their control, they stopped in its course by sails, and thus carried vessels over the ocean. Still, the air owed

the mechanist no obedience, and gave him none; nor could steam, a force as indocile, be brought into subjection by such rude contrivances and rough workmanship as had been applied for the control of grosser bodies.

The improvement effected by Mr. Watt in the construction of the engine, without reference to the alteration of principle and design, is shown by a comparison of the cylinder, piston, and rod of Newcomen's engine with those of his own. In the former, the cylinders were bored with little regard to accuracy, and the rough rod was attached to the piston by two or four stays or brackets, a mode of construction by which it was impossible correct action could be obtained. In Mr. Watt's engine, the piston-rod was accurately turned and finished, with a bright surface, and it moved steam-tight up and down through the cylinder cover in a contrivance called the stuffingbox, which is a metallic cup, lined with hemp or tow saturated with oil or tallow. The cover was fixed to the cylinder so accurately as to prevent the passage of air inwards and of steam outwards, and the piston and its rod were so attached that the motion from the top to the bottom was perfectly perpendicular. But all these precautions could not secure the accomplishment of Watt's designs while the boring of the cylinder remained irregular. To correct this evil, as far as possible, he made the piston so that it might be packed with hemp; but the necessity of improvement is always soon met by the discovery of the thing sought for. In a letter to Smeaton, from which