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BOOK VI. 



is broken and part of the chain or anything else should fall down ; he guides 

 the bag with a wooden shovel, and fills it with water if it fails to take 

 in the water spontaneously. In these days, they sew an iron band into the 

 top of each bag that it may constantly remain open, and when lowered into 

 the sump may fill itself with water, and there is no need for a man to act as 

 governor of the bags. Further, in these days, of those men who stand on 

 the floor the one empties the bags, and the other closes the gates of the 

 reservoir and opens them again, and the same man usually fixes the large 

 hook in the link of the chain. In this way, three men only are employed in 

 working this machine ; or even since sometimes the one who empties the 

 bag presses the brake which is raised against the other drum and thus stops 

 the wheel two men take upon themselves the whole labour. 



But enough of haulage machines ; I will now speak of ventilating 

 machines. If a shaft is very deep and no tunnel reaches to it, or no drift 

 from another shaft connects with it, or when a tunnel is of great length and 

 no shaft reaches to it, then the air does not replenish itself. In such a case it 

 weighs heavily on the miners, causing them to breathe with difficulty, and 

 sometimes they are even suffocated, and burning lamps are also extinguished. 

 There is, therefore, a necessity for machines which the Greeks call 

 TTviu^aTt^ai and the Latins spiritales though they do not give forth any 

 sound which enable the miners to breathe easily and carry on their work. 



These devices are of three genera. The first receives and diverts into 

 the shaft the blowing of the wind, and this genus is divided into three species, 

 of which the first is as follows. Over the shaft to which no tunnel connects 

 are placed three sills a little longer than the shaft, the first over the front, 

 the second over the middle, and the third over the back of the shaft. Their 

 ends have openings, through which pegs, sharpened at the bottom, are driven 

 deeply into the ground so as to hold them immovable, in the same way that 

 the sills of the windlass are fixed. Each of these sills is mortised into each 

 of three cross-beams, of which one is at the right side of the shaft, the second 

 at the left, and the third in the middle. To the second sill and the second 

 cross-beam each of which is placed over the middle of the shaft planks 

 are fixed which are joined in such a manner that the one which precedes 

 always fits into the groove of the one which follows. In this way four angles 

 and the same number of intervening hollows are created, which collect the 

 winds that blow from all directions. The planks are roofed above with a 

 cover made in a circular shape, and are open below, in order that the wind may 

 not be diverted upward and escape, but may be carried downward ; and there- 

 by the winds of necessity blow into the shafts through these four openings. 

 However, there is no need to roof this kind of machine in those localities in 

 which it can be so placed that the wind can blow down through its topmost 

 part. 



