634 THE ART OF CASTING BRONZE IN JAPAN. 



tlie blast is introduced. Each of the other segments consists of a cyl- 

 inder of fire bricks or slabs, cemented together with tire clay, and firmly 

 bound with iron bands. The number and size of these segments used 

 in erecting a cupola depends on the quantity of metal it is intended 

 to melt at each charge, and as a considerable number of various sec- 

 tions and degrees of taper are kept on hand, any form can be giveu 

 to the interior of the cupola. In all well-arranged foundries these seg- 

 ments, with their accompanying hearths of various sizes — generally 

 from 1 foot to 2 feet 3 inches in diameter — are always ready, so that 

 a furnace can be built up without delay at any time for either large 

 or small meltings. 



The cupola is erected by placing the hearth segment on a platform of 

 brick about 1 foot high, so that the tap hole may be of a convenient 

 height for tapping. Upon this segment one of the others is placed and 

 luted to it with fire clay; another is placed on this and similarly luted, 

 and others are added if necessary until the furnace is of suitable 

 height. The advantages which this method of erecting cupola furnaces 

 possesses for small foundries, where the work is of an irregular char- 

 acter, and where castings are often urgently needed which are too 

 large for crucibles and too small to justify the lighting up of a large 

 permanent cupalo, are self-evident. 



There is only one twyer, and this is the chief disadvantage of the 

 larger sizes of these furnaces, as it causes an unequal distribution of 

 heat in the zone of fusion, the results of which are undue volatilization 

 of lead and zinc in the overheated spaces and an unnecessary waste of 

 blast and fuel. There is no special charging door, the fuel and metal 

 being sinq)ly thrown into the open top of the furnace. 



Portable furnace for melting bronze. — Another furnace which is not now 

 in use in Japan, but is still employed in China, resembles the hearth 

 segment of the cupola I have just described. It is, however, made light 

 and portable, stands on three feet, and is fitted with sockets in its 

 sides, into which long handles are inserted, so that it can be carried 

 by two or four men. It is i^laced in front of a bellows, as shown, 

 and then charged with charcoal and bronze. When sufficient of 

 the latter has been melted it is carried to the mold, the fuel raked 

 ofti, and the molten metal poured through a beak- shaped opening in 

 its side. 



For objects of small size and complicated forms and of delicate model- 

 ing the bronze is melted in crucibles in small furnaces, which, like the 

 cupola, are worked by means of a blast. This form of furnace consists 

 of a simple cylindrical chamber, with a lining of fire clay, generally 

 partly embedded in the ground of the melting room, and fitted with a 

 movable clay cover. Its sides are pierced with four or six. or more 

 holes, about 3 to 5 inches above its base, for the admission of the blast. 

 The fuel used is charcoal. Kecently air furnaces connected with cliim- 

 ney stacks, similar to those of Europe, ha\'e been erected in many 



