Manchester Memoirs^ Vol. xlii. (1898), No. 6. 3 



skill, experience and devotion are at least equal to those 

 which have been already employed. 



It was only on the occurrence, five years later, of cir- 

 cumstances which seemed to afford an opportunity, such 

 as might not again occur, of obtaining the measure, in 

 mechanical units, of the total heat necessary to raise water 

 from 32° to 212°, the physically fixed points of temperature, 

 and of thus placing the heat, in mechanical units, on the 

 same footing as the unit of heat defined by temperature, 

 without the intervention of the scales of thermometers, that 

 the research was contemplated, and then after considerable 

 hesitation. 



The recognition of the responsibility even in attempt- 

 ing such a determination, and the harm to science that 

 might follow from further confusion owing to errors in 

 what, in spite of opportunities, must be the extremely 

 difficult task of making such a complex determination 

 within less than the thousandth part, together with 

 the author's inability to devote the time necessary, pre- 

 vented any attempt until July, 1894. At that date 

 Mr. W. H. Moorby offered to devote himself to the 

 research, and so to relieve the author from all responsi- 

 bility except that which attached to the method and 

 appliances, so that having, from experience, formed the 

 highest opinion of Mr. Moorby's qualification, there 

 appeared no excuse for further delay, particularly as, after 

 seeing the appliances, both Lord Kelvin and Dr. Schuster 

 expressed strongly their opinions as to the value of the 

 research. 



The opportunity for the research consisted in the 

 inclusion in the original equipment of the Whitworth 

 Engineering Laboratory, in 1888, of the following 

 appliances : 



(i) A set of special vertical triple-expansion steam 

 engines, with separate boiler, closed stoke-hold and forced 



