“1st. Prepare a wooden core, or mandril, of the size and form of the inside of the trumpet.
“2ndly. Place the strap of bronze to hold the rivets in the centre of its inner surface.
“3rdly. Cut the plate of bronze which is to form the trumpet to such a size that, when folded on the core, the edges may meet accurately on the centre of the bronze strap: hold all together by solder, or by any other means—perhaps coils of wire may have been used.
“4thly. Drill the holes for the rivets, countersinking them on the outside. See Plate XXIX., fig. 1.
“5thly. Remove the wooden core.
“6thly. By means of a cleft stick (or other contrivance) insert the rivets from the inside, outwards.
“7thly. As each rivet passes through to the surface it is to be drawn up as tightly as possible; the shank is to be bent back, or held up by any other means, so that the head of the rivet shall not be allowed to fall.
“8thly. Having inserted all the rivets, insert a metal core, or mandril, fitting the interior with great exactness.
“9thly. Complete the riveting from the outside, the metal core preventing the rivet-heads from being disturbed, and allowing the countersunk portion of the hole to be securely filled by a portion of the shank.
“10thly. Remove the metal core. The trumpet is now ready to be burnished off.