WATT. 139 



engine, at this time used only for pumping out water in mines, thus 

 became a true steam-engine of immense power, capable of being 

 worked with economy, and of being turned to the various uses to 

 which science has since applied it. For these great improvements 

 a patent, dated January 5, 1769, was taken out by Watt and Dr. 

 Roebuck, the founder of the Carron iron works, with whom Watt 

 had become acquainted. Little, however, was done for some years 

 in manufacturing engines on a large scale ; Roebuck fell into diffi- 

 culties, while Watt, harassed, depressed in spirits, and in want of 

 money, was forced to obtain employment as a civil engineer and 

 land-surveyor. Among the many works that he was engaged on in 

 this capacity may be mentioned : the Crinan Canal, afterwards com- 

 pleted by Rennie ; the deepening of the river Clyde ; improvements 

 in the harbours of Ayr, Port Glasgow, and Greenock ; the building 

 of bridges at Hamilton and Rutherglen ; and lastly, surveying and 

 estimating a line of canal between Fort William and Inverness, 

 which was subsequently executed by Telford on a larger scale than 

 was then proposed, under the name of the Caledonian Canal. In the 

 latter half of the year 1773 Roebuck's affairs came to a crisis ; and 

 Watt, through the agency of Dr. Small, having been brought into 

 relation with Mr. Boulton, a man possessing an intimate knowledge 

 of business, with extended views and a liberal spirit of enterprise, 

 an arrangement was entered into between them, and the firm of 

 Boulton and Watt established at Soho. This was the turning point 

 in Watt's fortunes ; under the vigorous management of Boulton, his 

 great invention at length began to be appreciated, and the saving 

 of fuel was found to be nearly three-fourths of the quantity consumed 

 by Newcomen's engine. In 1775 an extension of the original patent 

 until the year 1800 was obtained. This gave a fresh stimulus to 

 Watt's fertile brain, and resulted in patents being taken out, between 

 the years 1781-1785, for the rotatory motion of the sun and planet 

 wheels (the crank having been pirated by Wasbrough), the expansive 

 principle of working steam; the double engine; the parallel motion; the 

 smokeless furnace ; the float to regulate the supply of water into the 

 boiler ; and the governor. At a later period Watt also invented the 

 indicator, by means of which the actual horse power of an engine 

 could be ascertained. This beautiful series of inventions in a measure 

 may be said to have perfected the machine, and at the present time 

 the condensing steam engine differs in no material respect from the 

 engine as Watt left it. 



While residing at Birmingham, Mr. Watt's house became the 

 resort of many learned men. In the meetings of the Lunar Society, 

 held at Soho House, originated his experiments on water, and be- 

 tween him and Cavendish is the honour divided of having first pro- 

 mulgated the theory of its composition. During the dispute which 

 arose upon this subject, Watt's reply, on a friend regretting that 

 another should have carried off this honour, is worth recording, as 



