[Illustration:  THE LOCKED AND CORDED BOX TRICK.  By DAVID B. ADAMSON.]

The dotted line, B, shows the size of the panel; the dotted line, C, shows the depth of groove in the front rail.  From this it will be clear that the panel is only held in place at the back and front, and that on sliding it toward the front it will be free out of the groove in the back rail.  Three sides of it are thus free, and a little manipulation will allow of its being taken out altogether, leaving plenty of space for the performer to get out, presuming him to have been locked inside the box.

If the panel were to be finished in this way, without further fittings, the secret would soon be discovered; and I now proceed to show how the panel is held in place and firm while under examination.

Determine the size of screws that are to be used in fixing the brass corner clamps.  Let us say No. 7 is decided on; and if brass screws are used, then get a piece of brass, Fig. 4, the exact diameter of the screw-head, and a little longer than the thickness of the framing.  If iron screws are to be used, then this piece must be iron.  Now bore a hole into which this bolt will fit closely, right through the framing at D, Fig. 2.  It is most important that the hole should be made close up to the edge of the panel, B, so that when the bolt is in it firmly holds the panel, and prevents it moving from back to front in the grooving.  Now get a piece of sheet brass, 1/8 inch thick, and cut it to the shape shown by E, Fig. 2.  The width of this piece should not be less than 3/8 inch, and it must be of such length that the end reaches to the middle of the top framing, as shown at L, Fig. 2.  This piece of brass is sunk in the top and front framing, as shown by the dotted lines, G, in Figs. 2 and 3, and also in section in the latter.

When the box is open, the lower or short arm of this lever, which is shaped as shown full size, at E, Fig. 8, is kept pressed down on the bolt, D, as shown by the dotted lines, E, E, E, Fig. 2, and E, Fig. 7, by of the spring, J, Fig. 2.

On the box being closed, a pin on the under edge of lid goes into the hole, L, Fig. 3, and presses the end of the lever down in such a way as to raise the claw end of it from D. The thick dotted lines, F, F, F, Fig. 2, show position of lever when box is closed.

It will be noted that the bolt, D, Fig. 4, has a groove cut in it all around, into which the claw fits.  This prevents the bolt being pushed backward or forward when the box is open.

The lever must be hung as shown, K, Fig. 2.  The exact position of this is immaterial, but it is as well to have the fulcrum as near the end as may be, in order that the claw may be raised sufficiently with only a small movement of the short arm of the lever.  Of course, the shorter the arm is, the more accurately the lid and pin must be made to close.

If the pin, pressing short arm down, be too short, the pressure will not be enough to release the claw, and consequently the performer might find himself really unable to get out of the box after it is locked.