148 THE POPULAR SCIENCE MONTHLY. 



the heap was of the desired height ; the outside of the mass of 

 charcoal and ore was then incased in a covering of rough stones 

 laid in a mortar of clay and sand, or, in some cases, it was merely 

 plastered over with a thick layer of such mortar ; care was always 

 taken to have a hole near the bottom, just above the edge of the 

 hearth, for the insertion of a tube of baked clay to serve as a 

 tuyere, and a second hole at the top for the escape of smoke "and 

 gases. Fire was then introduced at the tuyere and the bellows 

 connected ; a gentle blast being used until all the moisture in the 

 ore and the covering of the heap was driven off. As soon as this 

 was accomplished, the blast was increased and the heat thereby 

 augmented. At the end of several hours a mass of metallic iron, 

 weighing twenty or thirty pounds, was found in the bottom of 

 the hearth, from which it was removed by tongs and forged by 

 sledge-hammers into the desired shape, several reheatings being- 

 required. The iron obtained was not usually over twenty per 

 cent of that in the ore, and only the richest ores were used. 



The first attempts to smelt iron-ore were probably made in 

 open, or perhaps partially inclosed, fires, in which the operation 

 was conducted without the stimulus of a blast ; but the slow and 

 very irregular burning of the fuel during calms, as compared 

 with its more rapid and effective combustion when urged by a 

 high wind, must have soon suggested the desirability of a regu- 

 lar and manageable method of supplying the primitive furnaces 

 with a current of air, and we find that the use of some contriv- 

 ance for this purpose is of great antiquity. 



Bellows are known to have been used by the Egyptians over 

 three thousand years ago. They consisted of a pair of leather 

 bags (which were nearly spherical when inflated), to each of 

 which was attached a tube for the discharge of the air.* The 

 operator stood with a foot on each of these bags, and pressed them 

 alternately by throwing his weight from one foot to the other. 

 In the top of each bag was a round hole, which could be closed by 

 the foot of the workman, and a cord held in each hand enabled 

 him to distend and inflate either bag as he compressed the other. 

 His feet served as valves to prevent the escape of air from the 

 holes, and compelled it to pass through the discharge-pipe into 

 the fire. 



Piston bellows were known in Egypt at least two thousand 

 years ago, and compressed air was used for various purposes 

 other than blowing fires. The kind of bellows shown in Fig. 1 was 

 known and used by the Greeks and Romans at a very early period, 

 and the bellows of our kitchens are of equal antiquity. Bellows 



* Tcrhaps the expression "a pair of bellows," which in the days of "open hearth " 

 practice in our older kitchens was quite common, had its origin in an equivalent Egyptian 

 colloquialism. 



