And of this Kind are the hollow cylindrical Tubes, of _different_ Lengths, and about a Foot in Diameter,[138] which are _cast_, for the Conveyance of Steam, from the Boiler of a Steam-Engine. Such a one, (previously lined with a Cylinder of Copper, or malleable Iron, to prevent the Adhesion of the Borings, when reduced to a Calx by the Admission of Steam;) might be placed horizontally over a Stove, (with or without a Chimney) and surrounded with _red_ hot Coals. The Ton of Borings might be deposited at one End of the Tube; and, by Means of the Air-tight flexible leathern Case, be pressed with a Rake, _gradually_ into the Fire, and _beyond_ it when calcined. Care must be taken to make the _Apparatus_ nearly Air-tight. The Steam shoud pass into the Tube, from _below_: and the Gass be conducted towards the Balloon throu’ another Iron Cylinder, nearly equal in Diameter and at right Angles with the first; lying also in an horizontal Direction; along the Ground. The Tubes might be _forged_ or _cast_, so as to form but one rectangular Piece. The further End of the second Tube shoud communicate with a _third_, made of Tin, and bent downwards about a Foot; thence at right Angles, for six Inches: then to rise up, also at right Angles, the Length of six Inches more. The Tin Tube is to descend into a Cistern of cold Water, made to flow over continually, by a fresh Supply; and into which, a few Lumps of Quicklime shoud be thrown. The Gass, which will press upwards throu’ the Water, is to be received into an inverted Funnel, and thence (as in Section 339, Art. 2.) conveyed to the Balloon. VI. 437. The following Alterations woud supersede the Use of the Rake, and _leathern_ Cases: the latter of which, by any accidental Crack or Flaw in the Leather, might admit a sufficient Quantity of common Air to produce an Explosion. The cylindric Form of the Copper, or malleable Iron (to be used as a Lining for the Tube) is to be changed, into that of a half Cylinder, or inverted Muffle: and to be perforated with small Holes. This Muffle is to be _nearly_ filled with a Ton of Iron Borings: (the Ends to be made up, to prevent the Borings from falling out into the Tube;) the Muffle itself is to be supported by a Cradle[139] of the same Form, made of +strong+ Copper Wire,[140] like the _open_ _Iron-Wire_-Fenders: and the whole is to be thrust into the Tube. The Length of the Muffle depends on the Quantity of Borings that are intended to be used. The Ends of the Tube shoud not be made so strong as the Tube itself: that, if an Explosion happens, they _may_ give way first, and prevent a Rupture of the Tube: not that any Danger is to be apprehended, that such an Event will take Place, so long as the Steam-Pipe is attended to, by a proper Person: the above Caution being only given, to prevent a Possibility of Rupture. Each End shoud be cast, or forged with a hollow Handle; and shoud screw into the Tube.