[Illustration:  Turn Down Shelf]

1-1/2 in. thick, and 4 to 6 in. wide, is first fastened to the wall at the proper height with nails, or, much better, large screws.

The shelf is cut and planed smooth from a board 12-in. wide and about 1-in. thick.  This board is fastened to the piece on the wall with two hinges as shown in Fig. 1.  A small cleat is nailed to the outer and under edge of the board and in the middle as shown.  This is used to place a support under the outer edge of the shelf.  The support, A, Fig. 2, should be long enough to extend diagonally to the floor or top of the baseboard from the inner edge of the cleat when the shelf is up in its proper place. —­L.  L.

** Home-Made Electric Battery Massage [144]

A simple and cheap electric massage device can be made by using three or

[Illustration:  Electric Massage]

four cells of dry battery connected to two ordinary silver tablespoons, as shown in the sketch.  The handles of the spoons should be insulated or the operator can wear either kid or rubber gloves.

** How to Make Tint Lantern Slides [144]

Purchase some lantern slide plates and fix them in hypo without exposing, in the usual manner, same as you would an exposed plate, says the Moving Picture World.  This leaves a thin, perfectly transparent emulsion film on the glass, which will readily take color.  Mix a rather weak solution of clear aniline dye of the desired color and dip the plate in it, wiping the plate side clean.  If not dark enough, dip again and again until desired tint is attained, letting it dry between each dipping.  A very light blue tint slide will brighten a yellow film considerably, but the tint must be very light, just a bare tint.

** A Bicycle Catamaran [145]

The accompanying photographs show a bicycle boat made to carry two persons.

[Illustration:  This Catamaran Carries Two People]

This boat is constructed by using two galvanized iron tubes 18 ft. long and 12 in. in diameter, tapered at the front end down to cast-iron points, and the rear end shaped to attach rudders.  These tubes are placed 26 in. apart, giving the boat an extreme width of 50 in.

The cylinders support a platform and on the rear end of this platform is constructed a paddle wheel 52 in. in diameter with 16 spokes.  On the end of each spoke is fastened a galvanized sheet metal blade 6 in. wide and 8 in. long.  A large guard placed over the paddle wheel forms a seat for one person and a chair in front on the platform provides a place for a second person.

The person in front helps to propel the boat with hand levers which are connected with rods to sprocket wheels on each side of the platform.  The occupant of the rear seat contributes his part of the power with his feet on pedals of the shaft that carries the sprocket wheels.  This shaft and sprocket wheels drive the paddle wheel by side chains of the bicycle kind.  The boat is steered from the rear seat by ropes attached to double rudders.  This boat will run at considerable speed and is very steady in rough water as it goes directly through large waves instead of going over them.  —­Contributed by Ernest Schoedsack, Council Bluffs, Iowa.