glass, opera glass, or bicycle lamp (C). Two pieces of tin reflectors, 6 by 10 inches (D). One tin can or piece of sheet tin large enough to form a tube 21⁄2 inches in diameter (E). One piece of stiff, springy wire, bent to form a ring about 211⁄2 inches in diameter, that will tend to straighten out and in so doing will hold the lens as well as itself in place. Remove lid from the box. In the side of the box which you have chosen for the front cut a circular opening about 211⁄2 inches in diameter for the lens. The center of this circle should be centrally located lengthwise of the box but slightly above the center of its depth. (See fig. 3.) Cut an opening 6 by 8 inches in the back of the box, 6 inches from the ends and about 311⁄2 inches from the bottom. Cleat the boards together to form a door to be hinged to the bottom of this opening. Putty up all knot holes and cracks between the boards, as the successful operation of the reflectoscope depends upon the box being light proof. Paint the inside of the box (sides, top, bottom, and ends) with lampblack thinned with turpentine. This is important, because any reflections other than those produced by the lamp reflectors and the picture will impair the operation of the reflectoscope. Fasten a lamp socket in each of the two front corners of the reflectoscope, connect the sockets in parallel, and run the connecting cord through the bottom of the box. Immediately in back of each lamp (B) and across the front corner of the box tack a shiny tin reflector (D) which has been bent to form an arc. Secure

SLED

Two pieces, 2532 by 32 by 36 inches, for runners (4). One piece, 16 by 9 by 20 inches, for seat (B). Three pieces, 2532 by 2 by 912 inches, for cleats (C). One piece broom handle 11 inches long. Four 2-inch angle-iron braces.

Shape runners (4) as illustrated in Figure 4. Cut a slot 1 by 6 inches midway between the ends. Bore a hole near the front end of each runner for the short piece of broom handle. Nail cleats (C) between the runners 5 inch below the top edgesone cleat 51⁄2 inches from the rear ends of the runners, one 234 inches from the rear ends, and a third midway between the other two. To strengthen the joints between the runners and the front and rear cleats screw two angle irons to the underside of each. Then nail seat (B) across cleats (C). Halfoval or flat iron pieces 36 inches long and 4 inch wide screwed to the bottom edges of the runners will save them and make the sled slide better.

SUBMARINE

One piece, 16 by 10 by 24 inches, for body (A). One piece 1 by 116 by 5 inches for conning tower (B). One piece 1⁄2-inch dowel, 4 inches long, for periscope (C). One piece tin, 1 by 3 inches, for stabilizing fin (D). Two pieces tin for diving elevators (E). One piece tin for rudder (F). Tin

the boards in place, forming the top of the box. It is suggested that the board immediately over the lamp sockets be screwed in place, so that it may be readily removed. Construct the lens mounting. The mounting may be made from sheet tin or a tin can with the top and bottom removed. Bend over the edges of one end of the can to form a flange against which the lens may rest. Then in back of the lens place the ring spring to keep it in place. If the diameter of the can is slightly larger than that of the lens, bands of cardboard strips may be used to cause the lens to fit tightly in the jacket. The lens jacket should fit loosely, so it will be free to slide back and forth for focusing. A tin collar cut to fit around the lens mounting and tacked to the front of the box will prevent light from escaping. Two pieces of wire and a light strip of wood should be fastened to the inside of the door as shown, to hold the cards or pictures to be thrown on the screen. Spools may be fastened to the bottom of the box for feet. Inasmuch as the reflectoscope reflects the image of an object on a screen, specially prepared plates are not necessary as in the case of the magic lantern, in which the light must pass through the plate. The reflection of any pictures, post cards, or other objects may be greatly magnified on the screen by simply placing them in the holder on the door, closing the door, and turning on the lamps in the box. The room must be darkened. As the lens reverses the pictures, they should be placed upside down in the holder in order that they may show right side up on the screen.

to form ballast dump pan (ID). Wire for trigger (G). Two pieces of tin for pan pivots (D).

Shape body piece (A) as illustrated in Figure 5. Cut a slit in the front edge of sufficient depth to hold stabilizing fin (D). Shape conning tower (B) and nail it on the top center of (A). Insert periscope (C) in (B) near the front end. Shape diving elevators (E) and rudder (F) and secure them to the rear end of (4). The proper shapes and dimensions of these pieces can best be determined by experiment. Shape ballast dump pan (H), as shown, to hold sufficient sand or gravel to sink the submarine-approximate dimensions, length 6 inches, depth 21⁄2 inches. Cut slot in the rear end of (H) so that trigger (G) will rest in it when the pan is in the upright level position shown. Cut out the bottom center of (A) so pan (H) will fit easily in the slot. Pivot the pan on a wire running through it and holes in pivots (D). Shape wire trigger as shown and fasten it to (A) so that the short flat part of the wire will drop into the notch in pan (II) when it is in the upright position illustrated. Place just enough sand or gravel in ballast pan to sink the submarine; set wire trigger to hold (H) from upsetting. See that the rear ends of diving elevators are bent downward slightly. Place submarine in the water. As it sinks the submarine is steered forward by the diving elevators. Upon striking the bottom, the wire trigger is forced upward, releasing ballast pan, which upsets, dumping the ballast, and the submarine rises to the surface

SKI SKOOTER

One piece, 116 by 314 by 36 inches, for runner (A). One piece, 2542 by 3 by 167% inches, for upright (B). One piece, 2532 by 1% by 12 inches, for brace (C). One piece, 2532 by 1% by 13 inches, for brace (D). One piece, 2532 by 6 by 12 inches, for seat (E). Two pieces, 2532 by 7% by 5 inches, for grip (F).

MINIATURE HOWE TRUSS BRIDGE

Six pieces, $16 by 5% by 48 inches, for bottom chords (4) and stringers (A1). Two pieces, 7/16 by 56 by 34 inches, for top chords (B). Sixteen pieces, 16 by 5% by 11 inches, for diagonals (C). Twenty-one pieces, $16 by 5% by 84 inches, for 14 floor beams (D) and 7 separators (D1). Wire for truss rods. Forty-six No. 4 machine screws 11⁄2

SKATEMOBILE

One box, any size (4). One beam, 15% by 311⁄2 by 36 inches (B). One cleat, 2532 by 11% by 8 inches longer than the width of the box (C). One roller skate or one pair of ice skates.

Securely fasten one-half of the roller skate to each end of the beam (B). If ice skates are used, one skate must be fastened to each end. Mount the box end up on beam (B) directly over the front skate. Nail the cleat (C) across the top end of (4), allowing an overlap of 4 inches on each side for handgrips. A smaller box may form a seat, mounted over the rear skate. (See fig. 8.)

each side of bolts through the 5-inch faces (see fig. 7). Cut the 16 diagonals (C) to the shape shown; the ends are cut off at an angle of 57° so as to be flush with the bottom and top edges of the bottom and top chords. Drill two 6-inch holes through the center of the 5-inch faces 10516 inches apart. Drill four 4-inch holes through the 546-inch edges of the floor beams (D), spaced 316 and 116 inches from each end. Drill two additional 6-inch holes through three floor beams, 21316 inches from each end. Bolt diagonals (C) between bottom chords (4). Bolt top chords (B) to other ends of diagonals (C). If holes have been correctly spaced, the bolts through the upper chords should be

directly over those through the bottom chord with the exception of those through the ends of (A) and those on each side of the center of (B). Stretch pieces of wire between the bolts through upper and fower chords as shown in Figure 7. Bolt floor beams (D) to the underside of lower chords (A). Bolt top-chord separators (D1) in place. In order to keep the bridge from skewing out of shape it may be necessary to bolt diagonals across the bottom. Bolt the two stringers (A1) in place across the floor beams (D). They should be so spaced as to come directly under the rails of the track. The diagonals (C) keep the bridge from collapsing and skewing out of shape. Metal rods or wire are used to hold the upper and lower chords (B) and (4) together. Cut ends of top chords (B) off at an angle of 57°, as shown. Drill eight 3-inch holes through the center of the 5-inch face. One hole is drilled 516 inch from each end. Two other holes are drilled 55% and 111⁄4 inches, respectively, from the end holes; the two

offers no resistance to compression, a weak construction results and permits weaving.

COASTER

One piece, 2542 by 4 by 20 inches (4). One piece, 2532 by 6 by 12 inches (B). One piece, 2552 by 4 by 12 inches (C). One roller skate.

Nail boards (B) and (C) to the ends of (A) as shown in Figure 9. Secure the front half of the roller skate to the underside of (A) at the (C) end, and the rear half of the skate to the underside of (A) at the (B) end.

BASEBALL-EQUIPMENT BOX

One box, 37% by 16 by 16 inches. One piece, 6 inch by inside depth by inside length of box (A). One piece, 16 inch by inside depth by inside width of box less 4516 inches (B). Two cleats for lid.

holes near the center are so spaced as to coincide with the holes through the upper ends of the middle diagonals when they are arranged in the position shown in the figure. Seven 16-inch holes are to be drilled through the 46-inch edge of upper chords (B); these holes should be so spaced as to permit the upper-chord separators to be bolted to the upper chords, immediately against the upper end of the diagonals, with the exception of the one to be fastened across the center of the bridge. The ends of the stringers (A1) are to be beveled off to conform to the slope of the incline leading to and away from the bridge. After the bridge has been correctly constructed it will be found to be most interesting to interchange the diagonals and vertical members. Substitute wire for the wood diagonals and pieces of wood for the wire vertical members. If this is done half the diagonals will be in tension or will tend to stretch, while the other half will tend to bend, as they will be in compression. As the wire

Remove the lid from box, cleat pieces together, and hinge to top of box. Nail partition (B) to (4) 4 inches from one end; then nail the partitions inside the box. Cut a hole 21⁄2 inches in diameter in one end of the box 24 inches below the top edge and 24 inches from the back of the box. Cut another hole 21⁄2 inches in diameter in the lid, as shown in Figure 10 over the narrow ball section.

HOME PLATE

Sufficient boards, about 2532 inch in thickness, to make a piece 16 by 17 by 17 inches. Three pieces of broom handle 14 inches long, sharpened at one end.

Nail the boards together to form the plate, 17 by 17 inches. Saw off two corners as shown in Figure 11, to form a 90° angle at the center of one end. Bore three holes for the broom-handle stakes. These may be bored through one or two thicknesses; in any