“Well,” said Mark, moving towards the door, “I don’t know,”--then stopping with an admirable assumption of indifference. “Suppose you had to stop up one end of a pipe, how should you do it?” “Make it white-hot,” said the smith. “Bring it to me.” “Will white-hot shut tight?” “Quite tight--it runs together when hit. Bring it to me. I say, where’s the punt?” grinning. His white teeth gleamed between his open lips--a row of ivory set in a grimy face. “The punt’s at the bottom,” said Mark, with a louring countenance. “Nice boys,” said the smith. “You’re very nice boys. If you was mine--” He took up a slender ash plant that was lying on the bench, and made it ply and whistle in the air. Mark tossed his chin, kicked the door open, and walked off. “I say!--I say!” shouted the smith. “Bring it to me.” “Keep yourself to yourself,” said Mark loftily. Boys indeed! The smith swore, and it sounded in his broad deep chest like the noise of the draught up the furnace. He was angry with himself--he thought he had lost half-a-crown, at least, by just swishing the stick up and down. If you want half-a-crown, you must control your feelings. Mark told Bevis what the smith had said, and they went to work, and the same evening filed off the end of the rod Mark had bought. Bevis’s plan was to file this till it almost fitted the tube, but not quite. Then he meant to make the tube red-hot--almost white--and insert the little block. He knew that heat would cause the tube to slightly enlarge, so that the block being cold could be driven in; then as the tube cooled it would shrink in and hold it tight, so that none of the gas of the powder could escape. The block was to be driven in nearly half an inch below the rim; the rim was to be next made quite white-hot, and in that state hammered over till it met in the centre, and overlapped a little. Again made white-hot, the overlapping (like the paper of a paper tube doubled in) was to be hammered and solidly welded together. The breech would then be firmly closed, and there would not be the slightest chance of its blowing out. This was his own idea, and he explained it to Mark. They had now to decide how long the barrel should be: they had bought rather more tube than they wanted. Five, or even four feet would be so long, the gun would be inconvenient to handle, though with a rest, and very heavy. In a barrel properly built up, the thickness gradually decreases from the breech to the muzzle, so that as the greatest weight is nearest the shoulder the gun balances. But this iron tube was the same thickness from one end to the other, and in consequence, when held up horizontally, it seemed very heavy at the farther extremity.