42 ELEMENTARY WOODWORKING 
Bung-head wire nails, or brads as the smaller sizes 
are called, have very small heads, which allow the nail 
to be sunk below the surface. This is done by means 
of the nail punch, or set, and is necessary when the sur- 
face is to be planed after the nailing. 
26. Screws. Screws are much used, and allow the 
pieces to be readily taken apart. They are divided 
into two classes, flat head and round head, and are of 
steel or brass. Steel screws are either blued or bright. 
Bright screws are polished and blued screws are pro- 
duced by treating the bright ones with heat or an acid. 
AN AG NK 
J Ye 
Fic. 55. Methods of using Screws 
Fig. 55 shows a flat-head screw at a and a round-head 
at b. Flat heads are used for the more common work 
where it is desirable to have the screw head flush (even) 
with the surface or below it, while round heads are used 
where this is not necessary. In the latter case round 
heads are used partly because they are more ornamental. 
Flat heads must always be flush or below the surface, 
and in all but the softest woods it is necessary not only 
to bore a hole for the screw, but also to countersink it 
with a countersink bit in order that it may receive the 
