352 NINETEENTH CENTURY. PT. in. 



He took a large piece of solid brass the shape of a can- 

 non, and partly scooped out at one end. Into this he fitted 

 a blunt steel borer, which pressed down upon the brass with 

 a weight of ten thousand pounds. Then he plunged the 

 whole into a box holding about a gallon of water, into which 

 he put a thermometer, and fastening two horses by proper 

 machinery to the brass cylinder he made them turn it round 

 and round thirty-two times in a minute, so that the borer 

 worked its way vigorously into the brass. Now notice what 

 happened : When he began the water was at 60 F., but it 

 soon grew warm with the heat caused by the friction of the 

 borer against the brass. In one hour it had risen 47 degrees 

 up to 107 Fahr.; in two hours it was at 178, and at the end 

 of two hours and a half // actually boiled. 



'It would be difficult,' writes Rumford, 'to describe the 

 surprise and astonishment of the bystanders on seeing so 

 large a quantity of water heated and actually made to boil 

 without any fire,' and he adds that he himself was as de- 

 lighted as a child at the success of the experiment ; and we 

 can scarcely wonder, for he had proved the grand fact that 

 heat is not a substance but a peculiar kind of motion. 



Rumford afterwards calculated that the friction caused 

 by one horse pulling round the cylinder against the borer 

 was sufficient to raise 26 Ibs. of ice-cold water up to the 

 boiling point in two hours and a half, thus showing that the 

 heat obtained has a definite relation to the energy expended 

 by the horse. 



Davy makes Two Pieces of Ice melt by Friction in 

 a Vacuum, 1799. Only a few months after Rumford had 

 made the discovery that heat can be produced by friction, 

 Sir Humphry Davy, whose history as a chemist you will read 

 in Chapter XXXVII., proved the same thing by a different 

 experiment. He took two pieces of ice, and by rubbing 



