IN using the hammer, the first thing to learn is to swing it with a free movement of the arm from the elbow rather than from the wrist, and the second is to strike squarely with the whole face of the hammer rather than with one edge. Begin by striking a moderately hard blow on your piece of waste wood, in one corner of the piece. Examine the mark made. You will probably find it deeper on one side than on the other, showing that you have not struck squarely. Strike again, by the side of the first mark, and examine the result, and so on, over the whole face of your piece of wood, or until you can strike hard and square.

Take a dozen four-penny nails and examine them. (Note that "four-penny" probably meant, originally, weighing four pounds to the hundred, and thus four-penny, six-penny, etc. give some indication of the size of the nails.) Observe that the nails have two sides parallel, as shown in the side-elevation, Fig. 21, b, while the other two sides, as shown in a, act as a wedge, and will split the wood if it is weak. The wedge, therefore, must be made to act in the direction in which the wood is strongest, that is, as we learned in Lesson III (Strength Of Wood)., in the direction of the length of the fibers.

Exercise 10. Striking With Hammer

Now, holding a nail between the fingers and thumb of the left hand, in the proper position to enter the wood without splitting, drive it into your piece of waste wood 3/8" from the end, till the point just shows through on the other side. Now draw it out with the claw of the hammer. To do this place a block of wood under the head of the hammer to lift it up to the height of the head of the nail; catch the head of the nail with the claw, and while the hammer rests on the block with the handle up, swing the end of the handle over so as to raise the claw, and the nail will come out. If the block is not used to raise the hammer, the nail will be bent. Drive the nail in the same way and draw it several times, always 3/8" from the end of the piece, but always in the first position, or so as not to split the piece. Afterwards, drive it several times in the second position, at the same distance from the end, and observe that you will nearly always split the piece. Note well these two positions. Observe that you can distinguish the one from the other by the shape of the head or by the way the nail feels between the fingers, and you should never hereafter split a piece of wood by carelessly driving a nail in the wrong way.

Fig.21.

Exercise 11. Driving And Drawing A Nail

Now, taking the long sides of your box, draw a light pencil-mark across each end, 3/8" from the edge, and make on this line two dots, each an inch from the end of the line, and a third half-way between them, for the places where the nails are to be driven, as in Fig. 22. Drive six nails nearly through at these places. Then, setting one of the short sides upright in the vise, lay the end of the long piece on it, exactly as it is to go when the box is put together, being careful, while holding the long piece in the left hand, to let the fore-finger reach round the edge, so as to feel whether the edge of the upper piece and the face of the lower piece are exactly even. Drive the middle nail through into the end piece, but do not drive its head quite down. This will now hold the piece firmly enough, while allowing you to adjust it and drive the other two nails down to the same distance. The heads of the nails are left projecting a little, so that it may be easy to draw them if necessary. The second corner may be nailed in the same way, and the six nails driven "home," that is, till the heads are even with the surface of the wood, taking care not to bruise the wood with the hammer. For the third and fourth corners lay the nailed piece down on the bench, with the short pieces standing up, lay the fourth side in place, holding it as you did the first, and drive the other nails with the same precautions as before.

Exercise 12. Nailing A Box

Fig.22.

If the pieces have been properly cut and properly nailed, the box will now be square at all its corners, the diagonals will be of equal lengths, and when it is set on the bench all the corners will rest on the bench and the sides will be perpendicular to it. You should test your work as to these particulars with rule and square.