5. A stove in which such moulds may be readily introduced, as require to be entirely deprived of humidity, and where a strong heat may be uniformly maintained.
6. Both blast and air furnaces, capable of melting speedily the quantity of cast-iron to be employed each day.
7. A blowing machine to urge the fusion in the furnaces.
[Fig. 467.] represents the general plan of a well-mounted foundry.
a, is a cupola furnace of which the [section and view] will be afterwards given; it is capable of containing 5 tons of cast-iron.
a′, is a similar furnace, but of smaller dimensions, for bringing down 13⁄4 tons.
a′′, is a furnace like the first, in reserve for great castings.
b, b, b, b, a vast foundry apartment, whose floor to a yard in depth, is formed of sand and charcoal powder, which have already been used for castings, and are ready for heaping up into a substratum, or to be scooped out when depth is wanted for the moulds. There are besides several cylindrical pits, from five to seven yards in depth, placed near the furnaces. They are lined with brick work, and are usually left full of moulding sand. They are emptied in order to receive large moulds, care being had that their top is always below the orifice from which the melted metal is tapped.
These moulds, and the ladles full of melted metal are lifted and transported by the arm of one or more men, when their weight is moderate; but if it be considerable, they are moved about by cranes whose vertical shafts are placed at c, d, e, in correspondence, so that they may upon occasion transfer the load from one to another. Each crane is composed principally of an upright shaft, embraced at top by a collet, and turning below upon a pivot in a step; next of a horizontal beam, stretched out from nearly the top of the former, with an oblique stay running downwards, like that of a gallows. The horizontal beam supports a movable carriage, to which the tackle is suspended for raising the weights. This carriage is made to glide backwards or forwards along the beam by means of a simple rack and pinion mechanism, whose long handle descends within reach of the workman’s hand.