Defcr'tptlon of an Air and a IVater-VauU. ^6^ 



part are three feet thick, befides a lining of brick and plader 

 from 18 inches to two feet. Still further precautions are 

 neceflary, and alternate layers of pitch and ftout paper are 

 requifite to prevent the efcape of the comprelfed air. C, a 

 view of the arched funnel which conveys the air from the 

 cylinder to the vault. Large iron pipes with a well fitted 

 door are preferable, and lefs apt to emit air. D, an end view 

 of the pipe by which the blalt is carried to the furnace. 



Fig. 2. is a horizontal fe£lion of Fig. i. at the dotted line 

 ab, reprcfenting the width of the crofs arches, which are 

 thrown in each partition to preferve an eafy communication 

 betwixt the vaults. D, is a fe6lion of the firft range of pipes, 

 meant to conduft the air to the furnace. In like manner 

 pipes may be taken off from any part of the vault for the dif- 

 ferent purpofes of blowing furnaces, fineries, hollow fires, &c. 



Fig. 3. reprefents a vertical longitudinal fe6lion of what is 

 generally called the water-vault. The walls of this building 

 may be erecled to the height of eight or nine feet, their 

 thicknefs fimilar to thofe of the air-vault. A brick lining, 

 and even puddling with clay betwixt it and the ftone build- 

 ing, is necelTary to prevent the water from oozing by the 

 accumulated prcffure. A, is an end view of the horizontal 

 range of pipes which conveys the blaft from the blowing cy-- 

 linder to the inverted chert. BBB, the range which condufts 

 the air to the interior of the inverted chert, and conveys it 

 to the furnaces, proceeding along the extremities of the co- 

 lumns broken off at B B. C, an inverted chert made of wood, 

 iron, or even of well-hewn flags fet on end and tightly ce- 

 mented, is 54 feet wiihin in length, 18 feet wide, and i a feet 

 liigh. The dimenfions, however, vary at dillcrent works. 

 When the chert is made of wood or iron, it is generally 

 bolted by means of a flange to the logs on wliich it is fup- 

 ported, left the great ])reflure of air fliould overcome the gra- 

 vitation of the chert, and difplace it. DD, view of the centre 

 log, and ends of the grofs logs, on which the chert is laid. 

 Thefe fliould mcafure 18 inches in height, fo as that thq 

 mouth of the chert may be that dirtance from the furface of 

 the floor, and the water allowed to retreat from the interior 

 yf the chert with the leart poUihle obrtruction. EE, the out- 

 3 A ?/ fidg 



