STEEL, AND THE BESSEMER PROCESS. 215 
recarbonising cupolas. A railway runs through the lower story of this 
building, and the coal and iron cars are lifted from it to the charging 
floor by another eight-ton hydraulic crane. The melted iron from the 
cupolas is run into a ladle hung on trunnions, and located on a platform 
scale, so that it may be exactly weighed and then quickly tipped into a 
trough which leads it into the converter. The recarbonising furnaces 
are similary arranged. 
The hydraulic machinery is driven by a Worthington duplex pump, 
specially constructed for this purpose. 
The blowing engine consists of two forty-two-inch blowing cylinders 
and two thirty-six-inch steam cylinders on the same rods, the strokejbeing 
four feet. The working air-pressure is twenty-five pounds per square 
inch, and the working horse-power 350. The valves of the blowing 
engine are bands of india-rubber, encircling the cylinder and covering 
and uncovering numerous small holes, thus giving a larger area with 
little stretching. This kind of valve is durable and noiseless under 
high pressure. The common flap-valve would obviously be inade- 
quate. 
The air is admitted to the converters, and the water to the various 
hydraulic cylinders and cranes, by cocks and handles situated on an 
elevated platform, where they may all be worked by a boy. Thus one 
boy accomplishes the work of fifty men. 
A pair of vessels of the same size, as arranged in England, will pro- 
duce only twenty-five to thirty tons per twenty-four hours. It has been 
the object of the writer, in arranging the new works described, to 
double the production, with a small addition to the cost of plant, and to 
economise labour and heat by more rapid working. 
The first improvement on the English practice was in facilities for 
repairing the more perishable parts of the converter. The tuyeres 
endure but six or eight charges. In England, they are renewed by 
knocking them out of their seats from the mouth of the converter by a 
long rod, putting in new ones from the tuyere-box and setting them 
with lining material, made semi-fluid with water, and poured round 
them from the mouth of the vessel. These wet bottoms are ten or 
twelve hours drying, and are not solid when dry. In the works at Troy 
the system of duplicate bottoms has been adopted. When the tuyeres 
are worn out, the whole bottom of the vessel is uncottered, lowered by 
a hydraulic lift, and removed by a crane for repairs. A duplicate 
bottom, hot from the oven, and in which tuyeres have been set in dry 
material and rammed, is by the same means attached to the converter. 
The vessel, still red-hot, is thus made ready for a new succession of 
charges in less than an hour. 
Further improvements have been made in doubling the capacity of 
the casting-pit, by causing the ladle to travel over two circles of ingot 
moulds ; in the addition of another ingot crane ; in making more room, 
within reach of the cranes, for the repairs of ladle linings, stoppeis, 
