486 Inquiry concemiing the Soinxe of 



the given time (150 minutes), nine candles^ burning at 

 once, would not be sufficient ; for 9 multiplied into 245 

 (the number of grains consumed by each candle in 150 

 minutes) amounts to no more than 2205 grains ; where- 

 as the quantity of wax necessary to be burnt, in order 

 to produce the given quantity of Heat, was found to be 

 2303.8 grains. 



From the result of these computations it appears, that 

 the quantity of Heat produced equably, or in a contin- 

 ual stream (if I may use that expression), by the friction 

 of the blunt steel borer against the bottom of the hollow 

 metallic cylinder, in the experiment under consideration, 

 was greater than that produced equably in the combus- 

 tion of nine wax candles^ each f of an inch in diameter, 

 all burning together, or at the same time, with clear 

 bright flames. 



As the machinery used in this experiment could easily 

 be carried round by the force of one horse (though, to 

 render the work lighter, two horses were actually em- 

 ployed in doing it), these computations shew further 

 how large a quantity of Heat might be produced, by 

 proper mechanical contrivance, merely by the strength 

 of a horse, without either fire, light, combustion, or 

 chemical decomposition ; and, in a case of necessity, the 

 Heat thus produced might be used in cooking victuals. 



But no circumstances can be imagined in which this 

 method of procuring Heat would not be disadvanta- 

 geous ; for more Heat might be obtained by using the 

 fodder necessary for the support of a horse as fuel. 



As soon as the last-mentioned experiment /"No. 3) was 

 finished, the water in the wooden box was let off, and the 

 box removed; and the borer being taken out of the cyl- 

 inder, the scaly metallic powder which had been pro- 



