This was cast into an oblong ingot, 1 to 12 in.
Ingot iron is slagless steel with less than 0.30% of carbon.
Forging proceeds by beating or squeezing the piece under treatment from its initial into its final shape, as for instance by hammering a square ingot or bloom first on one corner and then on another until it is reduced to a cylindrical shape as shown at A in fig.
If the ingot lay on its side while solidifying, the pipe would occur as shown in fig.
Gjers did this by setting the partly solidified ingot in a well-closed " pit " of brickwork, preheated by the excess heat of previous lots of ingots.