This section is from the book "Spons' Mechanics' Own Book: A Manual For Handicraftsmen And Amateurs", by Edward Spon. Also available from Amazon: Spons' Mechanics' Own Book.
Large pipes and cylinders are cast in a somewhat different way. A hollow vertical core of somewhat less diameter than the interior of the proposed cylinder is formed either in metal or brickwork. The outer surface of this is plastered with a thick coating of loam (which we may call A), smoothed and scraped to the exact internal diameter of the cylinder (by means of a rotating vertical template of wood), and covered with "parting mixture." Over this is spread a layer of loam (B) thicker than the proposed casting; the outer surface of B is struck with the template to the form of the exterior of the proposed casting, and dusted with parting mixture. This surface is covered with a third thick covering of loam (C), backed up with brickwork, forming a "cope" built upon a ring resting on the floor, so that it can be removed. The outer brick cope is then temporarily lifted away upon the ring. The coating (B) is cleared out, and the cope is replaced so that the distance between its inner surface and the outer surface of A is equal to the thickness of the casting. The metal is then run in between C and A. When cool, C and A can be broken up, and the casting extracted. The core, etc, have to be well dried in ovens before the metal is run.
B is often dispensed with, and the inner surface of C struck with the template.