These are among the simplest articles constructed out of sheet metal. The strip must be cut according to the directions already given for cylinders, allowing sufficient margin for the joint, whatever kind may be chosen. The strip is then bent throughout its length into a tubular form by encircling it around a stout circular pole of suitable dimensions, and the seam made in one of the methods illustrated in Fig. 216.

It should be stated, however, that in the case of the bent joints, the edges must be turned before bending the sheet into a cylinder; this is effected by hammering the edge over the hatchet stake with a mallet. In Fig. 216, a is a simple lapped joint adapted for articles demanding no great strength, and secured by soldering down the edge; in b, the 2 edges are hooked into each other, as it were, then hammered down and soldered; in c, an extra strip is hooked into the 2 edges, hammered down to assume the form shown in d by means of the punch e, and secured by thin soldering inside. These joints all refer to tinned iron (tin plate); in the case of copper and brass the edges would only abut instead of overlapping. Sheet zinc may be bent to any desired shape, but will not retain the acquired form unless it is heated to a temperature not exceeding that of boiling water, say 200° to 212° F. (93° to 100° C). Sheet brass may be cut and worked like zinc and tin. The same may be said of lead, which, however, has too little rigidity for many purposes; pewter often replaces it as being less soft and capable of taking a polish.

Pipes 217