III.
434. The Mode of Operation.
The Borings being spread on the Hearth, and red hot; the Steam Pipe is to be opened, and instantly shut. The Gass being suddenly extricated; the Pipe is to be opened, and shut again as before: the Borings pushed into the Dross-Pit, and a fresh Supply spread. This Process to be renewed, till the Inflation is completed.
If it be thought necessary to prevent the Steam from communicating with the whole Depôt of Borings, and so evolve too much Gass; a little Brass Door with Hinges of the same, might be made to hang from the Top of the Communication between the two Muffles: which Door opening inwards, and hanging vertically, woud by the Pressure of the Gass, stop up the Open: and yet, if made strong, not prevent the Operations of the Rake, at proper Times.