This is especially necessary in the case of reverberatory furnaces, which are essentially weak structures, and therefore require to be bound together by complicated systems of tie rods and uprights or buck staves.
In diameter, which had been supported by a large central post and about twenty uprights ranged round the circumference.
Its framework is composed essentially of four uprights, which rise from the corners of a square measuring loo metres on the side; thus the area it covers at its base is nearly 22 acres.
These uprights are supported on huge piers of masonry and concrete, the foundations for which were carried down, by the aid of iron caissons and compressed air, to a depth of about 15 metres on the side next the Seine, and about 9 metres on the other side.
This axis is a hollow forging of nickel steel, of which the accurately turned pivots rest on bearings attached to cast-iron uprights bolted upon a massive cast-iron base plate.