(fig. 84). The general appearance of this tool is familiar.
The kind required for the work of a manual training room is the ordinary carpenter's hammer, as in the illustration. It should not be very heavy - about No. 2 or 3. The head should be well balanced on the handle.
The pane, as the back process is called, is very useful in straightening nails when bent, and in many ways which fami-liarity with the use of the tool will teach.
The face should be of steel welded on the iron body, but hammer-heads made entirely of steel are very common. In any case a good hard face is wanted. The shape of the handle is important, When held at the extreme end, a good easy grip should be obtained, the length being not less than 1 foot. Through the outside of the hammer-eye, a wedge is driven to tighten the handle.
(fig. 85). This is a kind of wooden hammer, and is used to strike anything which the hammer would injure. The whole tool should be made of beech with twisted fibres. The mortice should diminish from the top of the head, as in fig. 86, and in putting the handle into the head it is passed through from the top. The reason of this is, that in the swinging blows administered with the mallet, the head would naturally tighten by the centrifugal force of the blow.
Inferior mallets are made with round handles. The curve of the top of the head should coincide with the segment of a circle, having the elbow of the operator for a centre, and the sides should form part of two radii, as shown in fig. 86.
When in use this aids in giving good square blows, and should be a very important consideration in selecting a mallet.
Fig. 87 shows the steel punch which is used to drive the heads of nails a little below the surface, when the projecting heads would be objectionable. To avoid slipping, the point is serrated slightly.
(fig. 88). The blade, it will be seen, is a spindle with the point flattened out into a wedge. It is important, however, that this should not be sharp, as chipping, both of the tool and the screws, is likely to happen. The handle should be round, or preferably oval, in section, to render the twisting movement easier.
Fig. 89 shows the pattern recommended.
The use of this tool affords a good opportunity for illustrating the principle of lever and fulcrum.
(fig. 90). There are several patterns of this tool, but that in the illustration is as good as any.
The peg is placed in a round hole through the top of the bench, and the screw, when it has reached the top of the peg, not being able to go further, lifts the arm by its subsequent action, pressing the iron plate firmly on the wood. This swivel plate has the advantage of pressing square and true on the face of the wood. It is serrated to ensure a firm grip.