232 LIFE AND EXPERIENCES CHAP. 



chemistry has astonished the world could not have 

 been achieved, whilst the knowledge of the quantitative 

 relations existing between the several forms of 

 energy, and the possibility of expressing their amount 

 in terms of ordinary mechanics, are matters which 

 now constitute the life-breath of every branch of ap- 

 plied science. For example, before Dalton's discovery, 

 every manufacturer of oil of vitriol a substance now 

 made each week in thousands of tons within a few 

 miles of this spot every manufacturer had his own 

 notions of the quantity of sulphur which he ought to 

 burn in order to make a certain weight of sulphuric 

 acid, but he had no idea that only a given weight of 

 sulphur can unite with a certain quantity of oxygen 

 and of water to form the acid, and that an excess of 

 any one of the component parts was not only useless 

 but harmful. Thus, and in tens of thousands of other 

 instances, Dalton replaced rule of thumb by scientific 

 principle. In like manner the applications of Joule's 

 determination of the mechanical equivalent of heat are 

 even more general ; the increase and measurement of 

 the efficiency of our steam-engines and the power of 

 our dynamos are only two of the numerous examples 

 which might be adduced of the practical value of 

 Joule's work. 



"If the place calls up these thoughts, the time of our 

 meeting also awakens memories of no less interest, in 

 the recollection that this year we celebrate the Jubilee 

 of Her Most Gracious Majesty's accession to the throne. 

 It is right that the members of the British Association 

 for the Advancement of Science should do so with heart 

 and voice ; for although science requires and demands 

 no royal patronage, we thereby express the feeling 

 which must be uppermost in the hearts of all men of 

 science, the feeling of thankfulness that we have lived 



