Oval-heads are used decoratively, the head filling the countersunk hole, as with flat-heads, and projecting a trifle besides.

They are much used in the interior finish of railway cars.

They are suitable for the strap hinges of a chest.
The thread of the screw begins in a fine point so that it may penetrate the wood easily where no hole has been bored as is often the case in soft wood.

The thread extends about two-thirds the length of the screw.

Any longer thread would only weaken the screw where it most needs strength, near the head, and it does not need friction with the piece thru which it passes.
The size of screws is indicated by their length in inches, and by the diameter of the wire from which they are made, using the standard screw-gage, Fig.