526 BOOK XI. 



the interior of the aich itself is of the same height as the walls. A chimney 

 is built upon the arches and the walls, and is made of bricks joined 

 together with Hme ; it is thirty-six feet high and penetrates through the 

 roof. The interior wall is built against the rear arch and both the side 

 walls, from which it juts out a foot ; it is three feet and the same number 

 of palms high, three palms thick, and is made of bricks joined together 

 with lute and smeared thickly with lute, sloping up to the height of 

 a foot above it. This waU is a kind of shield, for it protects the exterior 

 waUs from the heat of the fire, which is apt to injure them ; the latter can- 

 not be easily re-made, while the former can be repaired with Uttle work. 

 The hearth is made of lute, and is covered either with copper plates, 

 such as those of the furnaces in which silver is hquated from copper, although 

 they have no protuberances, or it may be covered with bricks, if the owners 

 are unwiUing to incur the expense of copper plates. The wider part of the 

 hearth is made sloping in such a manner that the rear end reaches as high as 

 the five vent-holes, and the front end of the hearth is so low that the back 

 of the front arch is four feet, three palms and as many digits above it, 

 and the front five feet, three palms and as many digits. The hearth beyond 

 the furnaces is paved with bricks for a distance of six feet. Near the 

 furnace, against the fourth long waU, is a tank thirteen feet and a palm 

 long, four feet wide, and a foot and three palms deep. It is Uned on aU sides 

 with planks, lest the earth should fall into it ; on one side the water flows 

 in through pipes, and on the other, if the plug be puUed out, it soaks into the 

 earth ; into this tank of water are thrown the cakes of copper from which 

 the silver and lead have been separated. The fore part of the front furnace 

 arch should be partly closed with an iron door ; the bottom of this door is 

 six feet and two digits wide ; the upper part is somewhat rounded, and at 

 the highest point, which is in the middle, it is three feet and two palms high. 

 It is made of iron bars, with plates fastened to them with iron wire, there 

 being seven bars — three transverse and four upright — each of which is two 

 digits wide and half a digit thick. The lowest transverse bar is six feet and 

 two palms long ; the middle one has the same length ; the upper one is 

 curved and higher at the centre, and thus longer than the other two. The 

 upright bars are two feet distant from one another ; both the outer ones are 

 two feet and as meiny palms high ; but the centre ones are three feet and two 

 palms. They project from the upper curved transverse bar and have holes, 

 in which are inserted the hooks of small chains two feet long ; the topmost 

 links of these chains are engaged in the ring of a third chain, which, when 

 extended, reaches to one end of a beam which is somewhat cut out. The chain 

 then turns around the beam, and again hanging down, the hook in the other end 

 is fastened in one of the hnks. This beam is eleven feet long, a palm and two 

 digits wide, a pahn thick, and turns on an iron axle fixed in a near-by timber ; 

 the rear end of the beam has an iron pin, which is three palms and a digit long, 

 and which penetrates through it where it lies under a timber, and projects 

 from it a palm and two digits on one side, and three digits on the other side. 

 At this point the pin is perforated, in order that a ring may be fixed in it 



