^jV Vauli of the Devon Iron Works, 113 



to return back to us. There was no appearance of wind to difturb the flame 'of our 

 candles ; on the contrary, I was furprifed to find, that when we put one of them into the 

 cdu£lion pipe, which conveys the wind fi'm the vault to the furnaces, it was not blown 

 out. There was not the fmalleft appearance of any drops of water ifluing out of this 

 pipe. The ouzing and dropping of water from the fide of the fock, next the bank, feemed 

 the fame as before the condenfation was made in the vault. In Ihort, every thing 

 appeared, in other refpefls, the fame as when we were in the common atmpfphere. 

 Having remained about an hour in the condenfed air, and fatisfied ourfelves that no water, 

 during that time, that we could in the leaft difcover, was agitated and forced out of the 

 rock and vault by the power of the blaft, as was imagined and infilled on, wc gave the 

 fignal to ftop the engine. As foon as it ceafed to work, and the condenfation abaied ,and 

 before the door of the vault was unfcrewed, the -whole vault, in a feiv feconds, became filled 

 luith a thick vapour, fo that zue could hardly fee the candles tit four or five yards difiance. The 

 door being now opened, the work people, anxious to know our fituation, and what had 

 occurred, came into the vault, and prevented any further obfervations. 



I now endeavoured to account for this curious appearance of tne water, which only 

 fliewed itfelf occafionally, in very fmall quantities, at the tweer, at a hole I ordered to be 

 made in the bottom of the wind cheft to colleft it more accurately, for it never was 

 obferved, but either when the engine, after working flowly, was made to work quicker, or, 

 after having been flopped for a few minutes, was fet to work again. 



I confidered the vapour which we had difcovered in the vault to arife from the moifture 

 of the fide of the rock next the furnace, which being expelled by the great heat of the 

 furnace, and converted into vapour, was able to force its way through the pores of the 

 rock into the vault, but that being in a manner confined v^ithin the rock, by the preflure 

 of the condenfed air, it found itfelf at liberty to come into the vault, only when the 

 condenfation abated confiderably, or was totally renaoved by the going flow, or (lopping 

 of the engine. It alfo occurred to me, that the' air, iij a flate of condenfation, might 

 poflibly be capable of holding a greater quantity of water in folution, which might pre- 

 cipitate fuddenly into vapour or mill when the condenfation abated. I imagined, there- 

 fore, that the very fmall quantities of water we at times difcovered, proceeded from 

 nothing elfe but this vapour, in its paflage to the furnace along with the blaft, being con- 

 denfed into water, by the coolnefs of the edufllon pipe and iron wind cheft. The quantity 

 of water did not appear to airrount to a gallon in twenty-four hours. 



A few days after I had made this experiment, the water ceafed entirely to make its 

 appearance, either at the tweer, or at the hole in the wind cheft ; but the furnace did not 

 come into heat for a long while after, and indeed not till the keepers let much more air 

 into it by a larger blow-pipe, and allowed lefs air to efcape at the fafety valve. It is pro- 

 bable that the rock was now beconxe perfedlly dry by the continued heat of the furnace. 



My experiment had the good eA'cft to remove all the prejudices againft the plan I had 

 adopted of blowing the furnaces, and likewife prevented the other partner from laying out 



Vol, IV. — June 1800. Q^ a large 



