584* TRAVELS IN THE 
furnace, but through the tubes ; by the opening and shutting 
of which they regulated the fire. These tubes were formed by 
plastering a mixture of clay and grass round a smooth roller 
of wood, which as soon as the clay began to harden was with- 
drawn, and the tube left to dry in the sun. The iron-stone 
which I saw was very heavy, of a dull red colour, with greyish 
specks ; it was broken into pieces about the size of a hen's egg. 
A bundle of dry wood was first put into the furnace, and 
covered with a considerable quantity of charcoal, which was 
brought, ready burnt, from the woods. Over this was laid a 
stratum of iron-stone, and then another of charcoal, and so on, 
until the furnace wasquitefull. The fire was applied through 
one of the tubes, and blown for some time with bellows made 
of goats' skins. The operation went on very slowly at first, and 
it was some hours before the flame appeared above the furnace ; 
but after this, it burnt with great violence all the first night ; 
and the people who attended put in at times more charcoal. 
On the day following the fire was not so fierce, and on the 
second night, some of the tubes were withdrawn, and the air 
allowed to have freer access to the furnace ; but the heat was 
still very great, and a bluish flame rose some feet above the 
top of the furnace. On the third day from the commencement 
of the operation, all the tubes were taken out, the ends of 
many of them being vitrified with the heat ; but the metal was 
not removed until some days afterwards, when the whole was 
perfectly cool. Part of the furnace was then taken down, and 
the iron appeared in the form of a large irregular mass, with 
pieces of charcoal adhering to it. It was sonorous ; and when 
