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V. Of the blowing of Air into Furnacesby a Fall of Water.

H E earliest method of animating the large firesI of the furnaces for smelting ores, appears to have■*" been by exposing them to the wind. Such wasthe practice of the Indians of Peru before the arrival ofthe Spaniards in that country. Alonso Barba relates,that their furnaces, called guairas, were built on emi-nences, where the air was freest ; that they were perfo-rated on all sides with holes, through which the airwas driven in when the wind blew, which was theonly time the work could be carried on ; that undereach hole was made a projection of the stone-work onthe outside, and that on these projections were laid burn-ing coals, to heat the air before its entrance into thefurnace. Some authors speak of several thousands ofthese guairas burning at once on the sides and tops ofthe hills of Potosi.

I have been informed, that several remains of a like rudeprocess are to be seen in some parts of our own coun-try. The old blomery hearths, as they are called, forthe running down of iron ore, are all on the tops of hills;a situation which can scarcely be supposed to have beenchosen on any other account than for the conveniency ofthe wind, being, in other respects, extremely incommo-dious.

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