“How much that looks like the letter V! That’s quite a different shape from the midship timber.” He put the rule beside this timber, and spread it apart till the shape corresponded. “How shoal it is!” holding it up.
The sight put an idea into the head of the keen-witted boy in an instant. He perceived that the shape of the bottom below the heads of the floor timbers corresponded exactly to the depth from the heads of the floor timbers to the keel; he laid a long rule across the heads of the middle floor timber, and measured the distance from the centre of that rule to the keel; it was three inches: he measured the forward one; it was six; the after one; it was six and a half: she was sharper aft than forward. He found that there was a regular gradation in the depth from the middle timber, both forward and aft. He took a board the length of the floor timber, found the centre of it, which corresponded to centre of the keel; from this point he drew a line three inches in height, then drew two others of the same height at an inch distance on either side, to represent the width of the keel: he then drew two lines from the edges of the keel to the ends of the board ([fig. 1]), when he found that he had the exact shape of the middle floor timber, and of course of the bottom at that place: he then took the shape of the forward one ([fig. 2]).
He had mastered the carpenter’s principle of the dead rise, although he didn’t know what to call it.
“Hurrah!” shouted the exultant boy, flinging the mould up over his head with such force that it knocked two hens, who were just settling themselves for the night, from the roost, and excited a general uproar. “I’ve got something to start from now; it’s the rise from the keel that shapes the bottom. When anybody is going to build a boat, they always know the length, width, and depth, and from that they can get all the rest. If I am going to build a boat eighteen feet long, four feet wide, and eighteen inches deep, she would be at the forward frame three feet on top; aft, three feet eight inches; middle, four feet. A line drawn through these points to the stem and stern gives me her shape on top; a depth and a half forward and a depth and a quarter aft gives me her sheer; half of her width on top gives me her shape at the heads of the floor timbers. Then all I’ve got to do to shape her bottom is, to lay off my rise, making it greater or less according as I want her full or sharp, dividing it up on the timbers, till I have twice as much in the forward floor timber as amidships, and a little more than that aft. I have got the top and bottom; I can get the shape of the side between those points by my eye; if I can’t I must be a fool.” The forward and after floor timbers determine the shape of the boat forward and aft; the timbers after that are V shaped; they do not cross the keel; and all that is necessary is to have a true taper to the stem and stern. “I feel kind of satisfied now; there seems to be some foundation, something to go upon; it ain’t all mixed up: now I have got all these moulds, it wouldn’t be half the work to timber out another boat of the same dimensions. Boat-building is real nice work after you know how; but to build a vessel—that would be the best. Now I’ll go in swimming, then look at my birds and go and see how my grafts come on.”
The next night, as he was busily at work after supper, getting out his gunwale, a well-known voice exclaimed,—
“Halloo! What’s all this?—steam-box, boat-building. I guess Elm Island will be a city soon.”
“O, Joe! I’m so glad to see you.”
“You be? I thought you didn’t like to have critics round, when you were at work.”