Fasten the sheet metal to a block of wood with handscrews or a vise. Punch a hole, with a nail set or punch, in the center of the circle to be cut, large enough to receive the spur of the expansive bit. A few turns of the brace will cut out the circle and leave a smooth edge. --Contributed by James T. Gaffney, Chicago.
** Key Card for Writing Unreadable Post Cards [35]
A key card for use in correspondence on postals that makes the matter unreadable unless the recipient has a duplicate key card is made as follows: Rule two cards the size of postal, one for the sender and one for the receiver, dividing them into quarters. These quarters are subsequently divided into any convenient number of rectangular parts-six in this case.
These parts are numbered from one to six in each quarter beginning at the outside corners and following in the same order in each quarter. Cut out one rectangle of each number with a sharp knife, distributing them over the whole card. Then put a prominent figure 1 at the top of one side, 2 at the bottom and 3 and 4 on the other side. The numbering and the cutouts are
shown in Fig. 1. The two key cards are made alike.
The key card is used by placing it over a postal with the figure 1 at the top and writing in the spaces from left to right as usual, Fig. 3, then put 2 at the top, Fig. 4, and proceed as before, then 3 as in Fig. 5, and 4 as in Fig. 6. The result will be a jumble of words as shown in Fig. 2, which cannot be read to make any sense except by use of a key card. --Contributed by W.J. Morey, Chicago.
The sketch shows an easily made, quick-working wood vise that has proved very satisfactory. The usual screw is replaced by an open bar held on one end by a wedge-shaped block,
[Illustration: Vise Made Entirely of Wood]
and the excess taken up on the other end by an eccentric lever. The wedge is worked by a string passing through the top of the bench and should be weighted on the other end to facilitate the automatic downward movement.
The capacity of the vise, of course, depends on the size and shape of the wedge-shaped block. --Contributed by J.H. Cruger, Cape May City, N.J.
** Toning Blue on Bromide and Platinum [36]
After some experimenting to secure a blue tone on bromide prints, a correspondent of the Photographic Times produced a very pleasing bluish green tint by immersing the prints in a solution composed of 30 gr. of ferricyanide of potash, 30 gr. citrate of iron and ammonia, 1/2 oz. acetic acid and 4 oz. of water. After securing the tint desired, remove the prints, rinse them in clean water for a few minutes, and then place them in a dilute solution of hydrochloric acid. Wash the prints thoroughly and hang them up with clips to dry.