Should it appear that the formation of the screw has been treated in greater detail than the other subjects with which it is associated, either as regards the modes of proceeding or the mechanism employed; the author would observe that it appeared to him that by this mode alone he could introduce, in something like order, a variety of interesting particulars, which although they have occupied very many pages, are but as a fragment of what might be said on a subject which has engrossed so much attention.

• Date of patent, 6th July, 1842. See Mechanics' Magazine, 1843, page † Rand's second patent for making collapsible veesels, 29th Sept 1842. Under the first patent the tin was drawn into tube, (see vol. i, p. 481,) and the convex and screwed ends were cast and soldered in; by the improved method the entire vessel is made from a small thick perforated disk of tin by one blow of a fly-press. The lower part of the mould has a shallow cylindrical cup, concave and tapped at the base; the upper part of the mould is a cylinder as much smaller than the cup as the intended thickness of the metal, which, on the blow being given is compressed into the screw, and ascends four or fire inches up the cylinder or ram. For large sizes a hydrostatic press is employed.