THE IMPROVEMENT OF THE ARTS AND MANUFACTURES. 15 



to them on the present occasion may appear to be trite and 

 common-place. I have reason to believe, however, that the 

 popular impressions on the subject, at present existing, are de- 

 fective, if not erroneous ; and that the general estimation of the 

 importance of philosophical attainments derived from them, 

 is not adequate to the real merits of the case: that the exam- 

 ple afforded by Mr. Watt's achievements is far more striking 

 and instructive than is commonly imagined. On this account 

 I will briefly review the train of investigation by which " this 

 potent commander of the elements, this abridger of time and 

 space," as he has been poetically denominated in reference to 

 the effect of his inventions on the welfare of society, was led 

 on to that construction of the Steam-engine, which has worked 

 such stupendous effects. I shall do this nearly in the terms 

 in which I have already explained it to my elder pupils at 

 Hazelwood ; which will enable the reader, in conjunction with 

 some examples I shall submit to him in the sequel, to judge, 

 in some degree, of the manner in which their instruction, in the 

 Physical Sciences, has been conducted. 



In the winter of the years 1763-4, Mr. Watt was employed 

 by the Professor of Natural Philosophy in the University of 

 Glasgow, Dr. Dick, to put in order a working model of a 

 Steam-engine upon Newcomen's or the atmospheric construc- 

 tion (the only one which had down to that period been de- 

 vised), in which the piston, giving motion to the machine, 

 was raised by the expansive force of the steam rushing into 

 the cylinder, and a vacuum being produced by the con- 

 densation of the steam in the cylinder, by the injection of cold 

 water, the piston was forced down again by the pressure of the 

 atmosphere upon its upper surface ; thus completing one 

 movement of the machine, and being prepared to repeat 

 it*. When Mr. Watt had repaired this model, and set it to 

 work, he found that the boiler, though large in proportion to 

 the cylinder, was barely able to supply it with steam for a few 

 strokes of the piston per minute ; and that a great quantity of 

 water was required to be injected into the cylinder in order to 

 condense the steam. It soon occurred to him that the cause 

 lay in the fact, that the little cylinder (of only two inches dia- 



* For all practical purposes the steam engine (constructed as above de- 

 scribed) must be considered as originating with Mr. Newcomen ; " the intro- 

 duction of a moveable diaphragm," as Mr. Davies Gilbert has philosophically 

 remarked, in his second paper on the efficiency of Steam Engines (Phil. 

 Trans. 1830), " between the active power and the vacuum or less elastic 

 medium, being essential to the very principle of the machine as a moving 

 power." The only material improvement it had received, down to the time 

 of Mr. Watt's inventions, consisted in the automatic opening and shutting 

 of the valves. 



