BOOK IX. 



361 



covered with lute so that they do not catch fire. In the secondary beams, 

 where they are laid on the fourth wall, are mortised the lower ends of the 

 same number of rafters as those in a set of rafters* opposite them. From 

 the third long wall these rafters are joined and tied to the ends of the opposite 

 rafters, so that they may not sUp, and besides thfey are strengthened with 

 substructures which are made of cross and oblique timbers. The rafters 

 support the roof. 



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The four long walls : A — First. B — Second. C — Third. D— Fourth. The 



SEVEN TRANSVERSE WALLS : E — FiRST. F — SECOND. G — ThIRD. H — FOURTH. 



I — Fifth. K — Sixth. L — Seventh, or middle. 



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In this manner the front part of the building is made, and is divided into 

 three parts ; the first part is twelve feet wide and is under the hood, which 

 consists of two walls, one vertical and one inclined. The second part is the 

 same number of feet v^dde and is for the reception of the ore to be smelted, 

 the fluxes, the charcoal, and other things which are needed by the smelter. 

 The third part is nine feet wide and contains two separate rooms of equal 

 size, in one of which is the assay furnace, while the other contains the metal 

 to be melted in the cupellation furnaces. It is thus necessary that in the 



^This set of rafters appears to start from the longitudinal beam. 



