THE PRESIDENTIAL ADDRESS 13 



the whole art of producing power by the agency of heat. The 

 steam turbine of Parsons, the gas engines of Otto and Dugald Clerk, 

 the oil engines of Daimler and Diesel, with all their social conse- 

 quences in making swift travel easy by road and possible by air, 

 are among the practical results. On the same thermodynamic 

 foundation was built the converse art of mechanically producing 

 cold, which we employ in ever-increasing measure for the import 

 and storage of our food. Joint experiments undertaken by Joule 

 and Thomson led to a further discovery which later enabled the 

 process of refrigeration to be carried very near to the limit of cold- 

 ness which Thomson himself established as the absolute zero. 

 In the hands of Linde and Claude the ' Joule-Thomson effect ' as 

 a means of producing extreme cold has created new industries 

 through the liquefaction of air and the separation of its constituents 

 by methods of fractional distillation. However cold, however near 

 the absolute zero, was the Association's first reception of Joule, we 

 may claim that in effecting a conjunction between him and Thomson 

 it made amends. Their meeting in 1847 ushered in a new era both 

 of scientific theory and of engineering practice. 



Of the Association's many other services there is little time to 

 speak. When the telegraph developed in the middle of last century 

 and spread itself across the Atlantic, largely under the guidance of 

 that same William Thomson (whom later we knew as Lord Kelvin), 

 there were no accepted units in which electrical quantities could be 

 measured and specified. The scientific world was as badly off 

 then for a standard of electricity as the commercial world is now 

 for a standard of value. The need of electrical standards was 

 urgently felt, by none more than Thomson himself. He stirred 

 the Association to act : a strong committee was set up, and in time 

 its work served as a basis of international agreement. There is no 

 danger that any country will wish to ' go off ' the standards thus 

 established. To settle them was an incalculable boon to science 

 no less than to technics. It paved the way for the revolution of 

 the eighteen-eighties, when electricity passed, almost suddenly, 

 from being no more than the servant of the telegraph to be master 

 of a great domain. It was then that the electric light and the electric 

 transmission of power gave it a vastly extended application, and the 

 fundatmental discoveries of Faraday, the centenary of which we 

 lately celebrated, came into the kingdom for which they had waited 

 nearly fifty years. 



Another notable achievement of the Association was to promote 

 the establishment of a National Physical Laboratory. Informal 

 talks, at our meetings in the nineties led to the appointment of 

 a CO mmittee which moved the Government of the day to take action. 

 The, Laboratpry was constituted, and Sir Richard Glazebrook was 



