1865.] REVIEW — YOUMANS ON FORCE. 157 



" Having taken away the borer, he found that 839 grains of 

 metallic dust had been cut away. ' Is it possible/ he exclaims, 

 ' that the very considerable quantity of heat produced in this 

 experiment — a quantity which actually raised the temperature 

 of upward of 113 pounds of gun-metal at least 70° — could have 

 been furnished by so inconsiderable a quantity of metallic dust, 

 and this merely in consequence of a change in the capacity for 

 heat ?' 



" To measure more precisely the heat produced, he next sur- 

 rounded his cylinder by an oblong wooden box in such a manner 

 that it could turn water-tight in the centre of the box, while the 

 borer was pressed against the bottom. The box was filled with 

 water until the entire cylinder was covered, and the apparatus was 

 set in action. The temperature of the water on commencing was 

 60°. He remarks, ' The result of this beautiful experiment was 

 very striking, and the pleasure it afforded amply repaid me for all 

 the trouble I had taken in contriving and arranging the compli- 

 cated machinery used in making it. The cylinder had been in 

 motion but a short time when I perceived, by putting my hand 

 into the water and touching the outside of the cylinder, that heat 

 was generated.' 



. " As the work continued, the temperature gradually rose ; at two 

 hours and twenty minutes from the beginning of the operation, the 

 water was at 200°, and in ten minutes more it actually boiled ! 

 Upon this result Rumford observes, 'It would be difficult to 

 describe the surprise and astonishment expressed in the counte- 

 nances of the bystanders, on seeing so large a quantity of water 

 heated and actually made to boil without any fire. Though there 

 was nothing that could be considered very surprising in this 

 matter, yet I acknowledge fairly that it afforded me a degree 

 of childish pleasure which, were I ambitious of the reputation of 

 a grave philosopher, I ought most certainly rather to hide than to- 

 discover.' 



" Rumford estimated the total heat generated as sufficient to raise 

 26.58 pounds of ice-cold water 180°, or to its boiling-point; and 

 he adds, ' from the results of these computations, it appears that 

 the quantity of heat produced equally, or in a continuous stream, 

 if I may use the expression, by the friction of the blunt steel 

 borer against the bottom of the hollow metallic cylinder, was 

 greater than that produced in the combustion of nine wax candles 

 each three-quarters of an inch in diameter, all burning together 

 with clear bright flames. 



