428 THE STEAM-ENGINE. 



a civil engineer ; but when he made known to him the improvements he had 

 [ projected in the steam-engine, Roebuck proposed to take out a patent for an 

 engine on the principle of the model which had been fitted up at Delft house, 

 and to join Watt in a partnership, for the construction of such engines. Sensi- 

 ble of the advantages to be derived from the influence of Roebuck, and from 

 his command of capital, Watt agreed to cede to him two thirds of the advantages 

 to be derived from the invention. A patent was accordingly taken out on the 

 fifth of January, 1769, nearly four years after the invention had been completed ; 

 and an experimental engine on a large scale was constructed by him, and fitted 

 up at Kinneal house. In the first trial this machine more than fulfilled Watt's 

 anticipations. Its success was complete. In the practical details of its con- 

 struction, however, some difficulties were still encountered, the greatest of 

 which consisted in packing the piston, so as to be steam-tight. The principle 

 of the new engine did not admit of water being kept upon the piston, to prevent 

 leakage, as in the old engines ; he was therefore obliged to have his cylinders 

 much more accurately bored, and more truly cylindrical, and to try a great 

 variety of soft substances for packing the piston, which would make it steam- 

 tight withomt great friction, and maintain it so in a situation perfectly dry, and 

 at the temperature of boiling water. 



While Watt was endeavoring to overcome these and other difficulties, in 

 the construction of the machine, his partner, Dr. Roebuck, became embar- 

 rassed, by the failure of his undertaking in the Borrowstowness coal and salt 

 works ; and he was unable to supply the means of prosecuting with the neces- 

 sary vigor the projected manufacture of the new engines. 



The important results of Watt's labors having happily at this time become 

 more publicly known, Mr. Matthew Boulton, whose establishment at Soho, 

 near Birmingham, -was at that time the most complete manufactory for metal- 

 work in England, and conducted with unexampled enterprise and spirit, pro- 

 posed to purchase Dr. Roebuck's interest in the patent. This arrangement 

 was effected in the year 1773, and in the following year Mr. Watt removed to 

 Soho, where a portion of the establishment was allotted to him, for the erec- 

 tion of a foundry, and other works necessary to realize his inventions on a 

 grand scale. 



The patent which had been granted in 1769 was limited to a period of 

 fourteen years, and would consequently expire about the year 1783. From 

 the small progress which had hitherto been made in the construction of engines 

 upon the new principle, and from the many difficulties still to be encountered, 

 and the large expenditure of capital which must obviously be incurred before 

 any return could be obtained, it was apparent that, unless an extension of the 

 patent-right could be obtained, Boulton and Watt could never expect any ad- 

 vantage adequate to the risk of their great enterprise. In the year 1774 an 

 application was accordingly made to parliament for an extension of the patent, 

 which was supported by the testimony of Dr. Roebuck, and Mr. Boulton, and 

 others, as to the merits and probable utility of the invention. An act was ac- 

 cordingly passed, in 1775, extending the term of the patent until the year 1800. 



Thus protected and supported, Watt now directed the whole vigor of his 

 mind to perfect the practical details of his invention ; and the result was the 

 construction, on a large scale, of the engine which has since been called his 

 SINGLE ACTING STEAM-ENGINE. 



It is necessary to recollect that, notwithstanding the extensive and various 

 application of steam power in the arts and manufactures at the time to which 

 our narrative has now reached, the steam-engine had never been employed for 

 any other purpose, save that of raising water by working pumps. The motion, 

 therefore, which was required was merely an upward force, such as was ne- 



