170 WATER IlLATED IN A BOIiER OF STONE. 



like the Dutch trafs *; and to convey the heat, two or tliree 

 copper tubes were placed in it from end to end, and the fur- 

 naces connedied to one end of the boiler, and the engine at 

 the other; which, though it was a prodigal way of faving 

 heat, yet it was competent enough to raife fleam for the ufe 

 of the engine in certain cafes. 

 When the water At the bottom of the boiler was placed a cock, as ufual, to 

 near the bottom *^P '*• ^^ occafion required, either when it was neceffary to 

 gave water, but clean it, or in cafe it (hould be over-charged with water, 

 tte heated, yvhich I think was the cafe which brought the following fad to 

 light; namely, that when the fire had been lighted, and (he 

 heat had to circulate through all this mafs of ftone-work, and 

 the water brought to boil, and the engine had been at work 

 lor the firft time, which is ufually attended with many unfore- 

 feen delays and hindrances, the cock being turned, the water 

 was not hotter than to admit the hand without any painful 

 lenfiition of heat. Many deep and grave hypothefes were 

 formed on this extraordinary difcovery, which, for the fake of 

 the profeffion at this advanced ftate of fcience, I mull forbear 

 to mention. But at that period many a valuable truth had 

 come and gone like a worihlefs mendicant, whom few re- 

 garded, and whom none would receive. 

 The tubes were Tiie moil ftriking circumftances in the detail of this difco- 

 and the vefTei a' ^'^^y ^^^' ^^'^^ ^^'^ temperature downward (for the tubes were 

 jiid conductor, near the furface of the water) muft be greatly accelerated by 

 the conducting power of the fides of the boiler, and the agita- 

 tion of the water in a ftate of ebullition : notwithftanding all^ 

 it muft have occupied four or five hours to bring the lower part 

 of the water to the temperature of 90°, or perhaps 100** ; and 

 no doubt can be entertained but that they deemed it a matter 

 of no confequencfc as to the place of the tubes, fo long as they 

 were covered with water ; believing with every body elfe, 

 that the whole mafs would attain ^he boiling point at the 

 fame lime. 



f^ail the man who throws if but one grain of truth into tlie 

 fcale againft popular prejudice or vulgar error; and notwith- 

 Uanding the Count did not obtain the extreme of precifion in 

 this particular infiance, he has laid the foundation for all the 

 fubi'equent experiments which have gone to confirm or rejecl 



* This lime is found on the beach on fome part of South Wales. 



the 



