Chapter XVII: Part II: A Festooned Kite (3)

The porch is a convenient play spot for the children, but must be properly safeguarded to prevent not uncommon accidents and injury by falls. The folding gate shown in the sketch provides substantial barrier to the head of the stairs, and may be quickly folded out of the way. It is hardly noticeable when set in the side of the pillar, and does not mar the finish or general effect of the latter.

The gate is made of strips of band iron, although wood may be used. The strips are fastened with bolts, or rivets, and the forward end is fitted to the section of the pillar, which forms the cover for the recess in which the gate is housed. The cover is hooked to the opposite pillar when the gate is opened. Any suitable height may be chosen for the gate, but, for the purpose suggested, 24 to 30 in. is satisfactory. The device may be adapted to a variety of other uses by providing a box or chamber for the collapsed gate, when no hollow recess is otherwise available.

A Homemade Book Holder

A piece of board and four finishing nails furnished me with the necessary materials to construct a book-holding apparatus when in a hurry. Each nail, being driven through the board, could be turned to release, and pulled out far enough to accommodate a thicker book. In fact the device was adjustable.

The Enchanted Card Frame

A mystifying card trick, in which the performer makes use of the enchanted card frame shown in detail in the illustration, is as follows: A pack of playing cards is given to one of the spectators, who selects a card, noting the number and suit. The card is then placed in an envelope and burned by the spectator. The performer takes the ashes and loads them into a pistol, which he aims at a small frame, shown as empty, and set upon a table a few feet distant. The frame is covered with a handkerchief, and the pistol is fired at the frame. On removing the handkerchief the selected and destroyed card appears in the frame, from which it is taken at the back.

FIG. 2

FIG. 1

FIG. 4

FIG. 5

A Pocket is Cut into the Frame, and Filled with Black Sand, Obscuring the Card When the Frame is Inverted]

The trick is performed as follows: A forced deck is prepared having 24 like cards, and the backs of the cards are held to the spectators when a card is selected. The frame is made of a molding 2 in. wide, mitered at the corners, and of the size indicated, the opening being 6³⁄₈ by 7¹⁄₂ in. The general views of the frame in normal position and inverted are shown in Figs. 1 and 5. A pocket is cut in the lower edge of the frame at the back, as shown in detail in Fig. 2. A pane of glass is fitted into the frame, and on the three edges other than the one having a pocket, strips of cardboard, ¹⁄₈ in. thick, are glued, as a bearing for a second piece of glass, as shown in Fig. 4. The back of the frame is fitted with a cover of thin wood, and a hinged door is arranged in the center of the back, as shown in Fig. 3.

A mat of black cardboard is fitted into the frame to form a background behind the card, Fig. 1. The pocket at the bottom is filled with black sand--that used by sign painters is satisfactory--and the frame is ready to receive the card for the performance of the trick. One of the cards from the forced deck is placed in the frame. By inverting the latter the sand is caused to run between the glass partitions, concealing the card on the black mat behind it. In this condition it is exhibited to the spectators and then placed upon the table. A handkerchief is thrown over it. The pistol is one of the toy variety and a cap is fired in it. In picking up the frame the performer turns it over, while removing the handkerchief, so that the black sand runs back into the pocket in the frame.--Harry Marcelle, Honolulu, H. I.

Portable Fence for Baby’s Play Area

BY L. N. ROBINSON

A child in the “toddler” stage should be provided with a safe place in which to play without disturbing the household routine of the busy mother too frequently. The folding wood-and-wire fence shown in the illustration meets this need in a practical and inexpensive manner. It may be used in the home or out of doors, the fence being especially useful in the latter case, since it protects the child, and likewise the lawn flowers, which a youngster, unguarded, may injure. The fence is 25 to 32 in. high, strong enough to support a grown person sitting on the edge of it, and incloses an area of about 4 by 6 ft. This is ample for the child, and the folded fence is thus not too bulky to be transported easily. The materials cost less than $3.50, including hardware for the making of the fence, as shown in the working drawings. The wood used for the main frames is ¹⁄₂ by 2 in., and they are covered with wire mesh, the edges of which are nailed under strips, on the outer side of the frames. Care should be taken to insure that none of the wire strands is exposed, thus endangering the child, or the clothes of passers-by. The frames are hinged together, as shown in the plan, and fold into compact form. Two long and four short frames are required. Cut the top and bottom rails of the long frames 6 ft. in length, and those of the shorter frames and the stiles 25 in. The corner joints are cross-lapped by cutting away one-half the thickness of each strip, as shown at A. The joints at the top and bottom of the center stile, or vertical piece, are made as shown at B, and the joints at the crossing of the center stiles and the cross braces, as at C. The braces only are notched to fit the stile. Each of the joints is fastened with flat-head screws, countersunk. The ends of the braces are cut to fit flush into the corners of the frames, and are nailed in place. This provides a flat nailing surface for the wire mesh and the strips that cover its edges.

Before putting on the wire mesh, all the exposed corners should be “broken” slightly with sandpaper, the wood wiped smooth, and finished with a coat of shellac. The wood may, of course, be left unfinished. In fixing the 1-in. wire mesh in place, fasten one end of the piece squarely at the end of the frame, nailing it with staples. Place a strip of wood under each end of the frame and bear down on the middle of the frame, or weight it, to produce a bowed effect. Then nail the other end of the wire securely; on removing the strips, the wire will be drawn taut. Tack the edges down, and repeat this process on the other frames. Next nail the covering strips on the front faces of the frames, mitering them at the corners, as shown at A.

The frames are then joined by means of hinges, as shown in the plan at A. Care should be taken that they are set so that the corners of the fence meet squarely and evenly when it is opened. Metal drawbolts should be fastened horizontally, one on the top of each folding joint between the end sections. These will prevent the child from folding the ends in, and possibly injuring its fingers. The completed fence is then given a final coat of shellac or varnish, the galvanized wire being left unfinished.

The materials required for the fence are as follows, the wood being listed in lineal feet, and smoothed on four sides to the dimensions indicated:

155 ft. ¹⁄₂ by 2-in. clear pine
50 ft. ¹⁄₄ by 1-in. clear pine
22 lineal ft. 1-in. mesh, 2-ft. wide wire fencing.
6 pairs 1¹⁄₂ in. iron plain butt hinges, with screws.
2 steel drawbolts, with screws.
¹⁄₂ pt. white shellac.

Water Rheostat for Small Electrical Devices

The rheostat shown in the illustration can be made quickly and at small expense. The base consists of a piece of wood, ¹⁄₂ by 2 by 12 in. A glass tube, 1 in. in diameter and 6 in. long, is fastened to this with strips of sheet metal. A large brass tack is driven into a cork, and the cork is inserted in the lower end of the tube. A wire runs from the brass tack to the binding post A. The lower part of the tube should be paraffined to make it water-tight. A brass or copper rod is placed through the binding posts B and C. The resistance can be changed by sliding the rod up or down. The tube is nearly filled with water having a small quantity of salt dissolved in it. The amount will depend upon the current to be reduced. The rheostat should be fastened to a wall, or other support, and may be used to regulate the speed of small motors and other electrical devices.--R. R. Wayt, Pittsburgh, Pa.

White Blotting Paper Improves Light Reflectors

In the lecture and classrooms of a large university it was found that reflections of the electric-light bulbs in the glazed porcelain reflectors were extremely annoying to the eyes of students, and concentration of sight on the blackboard was difficult. A number of tests were made, and the following method proved successful, eliminating the glare and the reflections. Large sheets of white blotting paper were cut to fit the inside of the reflectors, and then glued to their surface. The soft, somewhat rough surface of the blotting paper diffused the light, so that the glare was overcome.--C. M. Hall, St. Louis, Mo.

Two Simple Vises for the Home Workbench

Boys, and other amateurs, sometimes have need of a vise when a commercial article or one of standard type cannot be had readily. The devices shown in the illustration will give good service and can be made of material easily obtained. The vise shown in Fig. 1 was made of old machine parts, consisting of a bolt and a wing nut. The bolt A was flattened at one end and bent at a right angle. A hole to fit it was bored through the top of the bench B, and the washer C and wing nut D were put in place. The piece to be gripped is clamped under the end A. This device should be fitted near the end and front edge of the bench.

FIG. 2

These Vises may be Made Easily of Materials Available in Most Workshops]

The vise shown in Fig. 2 grips the block E in the same manner as the first vise. The jaw F is bolted to a vertical piece, G, which is fitted into a mortise cut through the bench top. The wedge H passes through a mortise in the piece G and clamps against the lower side of the bench top.--James E. Noble, Toronto, Can.

Drinking-Glass Holders Easily Made

Several styles of holders for a drinking glass are suggested in the illustration. They may be made of durable materials easily obtained in the home workshop. The first is made by twisting a galvanized-iron or brass wire, as shown, with an eye and a loop for fastening it to the wall. A cork is fixed to the upper end, on which to rest the glass. The lower sketch shows a holder of the cup type made by riveting a metal cup to a diamond-shaped plate, the latter being fastened to the wall. The holder at the right is made from a piece of sheet metal cut to the shape indicated below. It is bent to the shape shown, and the lower end of the narrow strip is curved upward to provide a rest for the edge of the glass. The upper portion of the holder should be large enough so that the glass may be raised sufficiently to fit into the rest. The holes are provided for a fastening.--Frank L. Matter, Portland, Ore.

Emery Needle Cushion on Sewing Machine

A convenient emery pad and needle cushion may be made by inclosing the powder in a long sack, about 1 in. in diameter, and sewing it in place around the arm of the machine. It will thus be close at hand and needles and pins may be stuck in the cushion, free from rust, and will not be in the way.

_by_ Edward R. Smith]

The possibilities for practical use as well as novelty for play and experimental purposes make the compensated aerial cableway, shown in the illustrations, not only interesting but also worthy of study. The arrangement assembled in its simplest form with two towers, in the page plate, shows how the weight of the car is compensated, so that a fairly level course on the track cable is provided. The various positions of the load and cables, showing the application of the compensating principle, are indicated in Figs. 1 to 5, and a multiple system is shown in Fig. 6. The details of the constructional parts are also shown. The car may be driven by wind power, as shown in Fig. 7, or by a motor, as in Fig. 8, in addition to the simple application of hand power suggested in the page plate. Devices for automatically reversing the course of the cars both for the sail rigging and with the use of electrical power, are shown in Figs. 7 and 8. By their use it is unnecessary to have an operator at each end of the cableway. The constructional features were worked out first by experiments on models in a shop, and then applied to a large rigging spanning over 100 ft. between the A-frames. The sketch in the page plate was made from photographs of this construction. Application of the compensating principle to carrying and transportation problems affords opportunity for interesting engineering, in spanning streams, cañons, or gulleys.

In most types of cableways a considerable sag is allowed in the cable supporting the car in addition to that caused by its own weight. Even in systems of practically constant cable tension, in which the wire is stretched by enormous weights, the loaded car causes a sag in the track cable, and ascends and descends an incline when approaching and leaving a tower. The aim in the compensated cableway is to overcome this sag as much as possible, and to offer a minimum of resistance to the car in its course.

The simple form of compensated cableway shown in the page plate is made by setting up two A-frames, with wire braces supporting them, and mounting the track and traction cables upon them. A light, flexible compensating cable extends from one tower to the other and is fitted to grooved pulley wheels at the tops of the towers, as shown in the detail at the right. The ends of the cable are fixed to wire hooks, from which the track cable is suspended. The latter is anchored at the ends of the wire braces supporting the A-frames. In order to understand the operation of the system it is desirable that the course of a load be traced in its various stages, as indicated in the diagrams, Figs. 1 to 5. For diagrammatic purposes the load is shown passing from the west slope to the east. As the load passes under the first A-frame, as in Fig. 2, the track cable is drawn down at that point; the corresponding end of the compensating cable is also drawn down, raising the opposite end of the track cable, and taking out most of the sag in the center portion of the track cable. As the load passes to the center position, as shown in Fig. 3, the track cable resumes a more nearly horizontal position. When the second A-frame is reached the load draws the corresponding end of the compensating cable down with the track cable, Fig. 4, and the latter assumes its normal position as the load reaches the end of the course. It is evident from the diagrams that the course of the load is more nearly level than it would be if the sagging of the track cable were not counteracted.

For use with a multiple-frame system, the cables are arranged in units between supports, as shown in Fig. 6. The compensating action is similar, the tendency being to level the entire course of the load. The weight of the car and load only is compensated, and since the weight of the cable will cause a sag, the course cannot be level, but may approach this condition.

FIG. 2

FIG. 3

FIG. 4

FIG. 5

FIG. 6

This Interesting Model Cableway was Built by a Boy for Play and Experimental Purposes: The Principle by Which the Weight of the Car is Compensated in Single and Multiple Systems is Indicated in the Diagrams Above. Cars Propelled by Sail Rigging or by a Small Battery Motor may Also be Used]

A model of the compensated cableway, as shown in the page plate, or on a smaller scale, may be made by a boy of fair mechanical skill. For experimental purposes the detail may, of course, be refined to a high grade of workmanship, if desired. The size and dimensions of the parts need not be proportioned precisely as shown, but may depend more or less upon the materials available. The track cable should be made of galvanized-iron wire, the compensating cable of fishline, and the towers of 1-in. stuff, the width of the pieces making up the A-frames being increased in proportion to the height. Grooved pulley wheels, set in housings fixed to the top of the A-frames, carry the compensating cable. These may be made of wood, built up in three sections, to provide a flange on each side of the cable groove. The A-frames should be joined strongly at the top, and braced to anchors, sunk into the ground as shown. The hooks from which the track cable is suspended are made of heavy wire, bent so as not to interfere with the H-frame hanger supporting the car, and looped around the cable.

Various types of hangers may be devised to house the two pulley wheels which ride on the track cable. A simple H-frame hanger is shown in the detail sketch in the page plate. The grooved pulley wheels are set on bolts, and a heavy wire is bent and set through the center block as a support for the car. For experimental purposes, or even for play, when it is not desired to make a more elaborate car, a wooden block or other object of sufficient weight may be used as a load. An interesting feature of the work, especially for a boy, is to devise a realistic coach model, as suggested in the sketch. A wooden block forms the base, and the roof and platforms are made of sheet metal. The windows and doors are painted on the metal. The inventive boy may, of course, build a car with a hollow metal or wooden body, and weight it properly to provide the necessary load.

The motive power is provided by means of a cord, or traction cable, carried around two large grooved pulleys, mounted in supports fixed to the landing stages at each end of the cableway. They are made of wood, a suitable groove being cut around the edge with a saw, and smoothed with a small round file, or sandpaper wrapped over a round rod. The traction pulley is turned by means of a crank, set on the bolt which is used as an axle. The traction cable must be drawn sufficiently taut to provide the necessary pressure on the grooved pulleys, or it will slip. Rosin applied to the pulleys and the cable will tend to prevent this.

The Car is Propelled by the Wind Action on a Sail Controlled Like the Main Sheet of a Sailboat in Tacking. The Trigger Device Releases the Sail, Reversing the Course of the Car]

If the frames and other fittings have been properly set up, the cableway will support a sail car, shown in Fig. 7, or a two-cell electric car, driven by a small motor, as shown in Fig. 8. The sailing-car arrangement is often feasible, since a stiff breeze is common in gorges, cañons, narrow valleys, or even in ravines where such a cableway might be set up. The hanger is an H-frame having the grooved pulleys bolted in it, and further reinforced by small blocks at the ends. A braced frame, supporting a deck on which a mast is set, is suspended from the hanger by four curved wires, as shown in the side view, Fig. 7. A sail with boom and gaff is supported by the mast. It is arranged to be shifted around the mast, which is accomplished automatically at the end of a run, or “tack,” by means of the trigger device shown in the top view. The sail is controlled in relation to the wind much as is the main sheet of a sailboat. The car can be operated in this manner only at right angles to the direction of the wind, or nearly so. For play purposes, a boy stationed at each end of the cableway can shift the sail, but the trigger device shown makes this unnecessary. A rubber band is attached to the boom, as indicated in the top view, and a cord and wire are arranged to engage a trigger. A stop for the trigger is fixed to the A-frame so that it is sprung when the car reaches the end of the run. The rubber band reverses the sail, the car having been set on the cable originally so that the forward end is in proper relation to the wind.

The Electric Car Is Self-Contained and may be Reversed Automatically, if the Motor Is of the Reversible Type, by Contact of the Lever with the Stop Fixed to the A-Frame]

The electric car is especially interesting in that it provides self-contained motive power by means of a battery of dry cells, and a motor belted to the hanger, as shown in Fig. 8. The hanger is of the H-frame type with heavy blocks between the sidepieces to provide for the small grooved driving pulley set on the axle of one of the larger pulleys. A wooden deck, supported by four heavy wires set into the center block of the hanger, carries the motor, and the dry cells are fixed under it. The motor is of the small reversible battery type, and should be provided with a reversing lever. This will make it possible to reverse the car when it reaches the end of its course. The motor and cells should be disposed so as to balance, tests being made for this purpose before setting them in place finally. A cord or small leather belt connects the drive pulley of the motor with the proper pulley on the hanger. These pulleys should be in line, and that on the hanger should be five times the diameter of the one on the motor shaft. The power is shut off at the end of the course by a shut-off switch which strikes a stop crank attached to the A-frame. When the reversing lever and stop are used, the stop crank is unnecessary. A nonreversing motor can be made to drive the car in a reverse direction by removing the belt from the motor pulley and replacing it to make a figure-eight twist.

* * * * *

¶When babbitt metal is heated some of the tin and antimony in it is
burned out, making it unsuited for use in machinery bearings, and
similar purposes, after several heatings. The oxidation of the metal
is indicated by the formation of a scum on the surface.

That Hurdles Trenches

BY EDWARD R. SMITH]

Among the engines of war in action on land, probably none has created greater interest than the now famous “fighting tank,” which, according to reports, pours out missiles of destruction on the enemy from armored turrets, and crawls over trenches, shell craters, and similar obstructions, like a fabled giant creature of prehistoric ages. The tank described in this article, while not as deadly as those on the battle fields of Europe, performs remarkable feats of hurdling trenches, and crawling over obstructions, large in proportion to its size. The model, as shown in the heading sketches, is full-armored, and has a striking resemblance to these war monsters. The turret is mounted with a magazine gun, which fires 20 projectiles automatically, as the tank makes its way over the rough ground. The motive power for the tractor bands is furnished by linked rubber bands, stretched by a winding drum and ratchet device, on the rear axle, as shown in Fig. 1. When the ratchet is released, the rear axle drives the fluted wheels on it, and they in turn drive the tractor bands, as shown in the side elevation, Fig. 6. The wire-wrapped flywheel conserves the initial power of the rubber-band motor, and makes its action more nearly uniform.

The tank will run upward of 10 ft. on the rubber-motor power, depending on the size and number of the bands used. The gun is fired by a spring hammer, actuated by a rubber band. The trigger device is shown in Fig. 1. The pulley A is belted, with cord, to the front axle. Four pins on its inner side successively engage the wire trigger, drawing it out of the gun breech B, and permitting another shell to drop into place. As the pulley revolves, the trigger is released, firing the projectile. This process goes on until the motor runs down, or the supply of shells is exhausted.

The tank is guided by the pilot wheel, shown in Fig. 1. The sheet-metal armor, with its turret, is fitted over the mechanism, and can be removed quickly. It bears on angles bent up, as detailed in Fig. 2, to fit on the ends of the wooden center crosspiece of the main frame, and is held by removable pins at the ends of this frame. While the rubber motor is easy to make and install, the range of the tank can be increased by using a strong spring motor, the construction otherwise being similar.

The construction is best begun by making the wooden frame which supports the armor. The perspective sketch, Fig. 1, used in connection with the working and detailed drawings, will aid in making the latter clear. Make the frame C, as detailed in Figs. 5 and 6, ³⁄₈ by 1³⁄₄ by 11 in. long, with an opening cut in the center, 1 in. wide, 1 in. from the rear, and 1¹⁄₄ in. from the front end. Make the crosspiece D ³⁄₈ by 1³⁄₄ by 5⁷⁄₈ in. long; the gun support E, as detailed in Fig. 4, ³⁄₈ by 1⁵⁄₁₆ by 6¹⁄₄ in. long. Shape the support E as shown. Fasten the frame C and the crosspiece D with screws, setting the piece D 5³⁄₄ in. from the front, and its left end 3 in. from the side of the frame, as shown in Fig. 5. This is important, as the fitting of the other parts depends on the position of these wooden supports.

FIG. 4

FIG. 1

FIG. 2

Perspective Sketch, Showing the Arrangement of the Parts, with the Armor and the Tractor Bands Removed, and Details of the Gun Mechanism and the Armor]

The drive-wheel axles are carried in sheet-metal hangers, F, shown in Figs. 1 and 5, and detailed in Fig. 6. These hangers also carry bearing wheels, G, Fig. 1, which are held between the hanger F and a metal angle, as detailed at G, Fig. 6. These wheels are cut on a broomstick, and mounted on nail axles. The metal for the hangers F is drilled as shown, and bent double at the ends to make a strong bearing for the drive-wheel axles. The upper portion is bent at a right angle and fits over the top surface at the end of the crosspiece D, and is fastened to it with small screws or nails. Cut the stock for the hangers 2 by 6³⁄₈ in. long.

Next make the sheet-metal support H, Fig. 1, for the flywheel, the rim of which is wrapped with wire to give it added weight. Cut the stock, as detailed in Fig. 6, 1³⁄₄ by 4³⁄₁₆ in. long, and notch it to form the spring arrangement, which holds the flywheel so that the belt will be tight. The other sheet-metal support may then be made also. Cut the stock for the front support J, for the rubber motor, 4¹⁄₈ by 3³⁄₄ in. long, and shape it as shown in the detail, Fig. 6. Make the support K from a piece of sheet metal, in general shape similar to that used for support H, the dimensions being made as required, and no spring arrangement being provided. Drill these metal fittings, as indicated, for the points of fastening, and mark the places for the holes in which shafts or axles run very carefully.

The driving mechanism can then be made, as shown in Fig. 1, and detailed in Figs. 5 and 6. The driving shafts and their parts, as well as the pulleys, can be turned in a lathe, or made from spools, round rods, etc. Make the front axle L, and wheels, joined solidly, 5³⁄₄ in. over all, the grooved wheels being ³⁄₄ in. thick, and 1⁷⁄₁₆ in. in diameter. Wires are used as bearings for shafts for the driving axles. If the rear axle is turned in a lathe, it is cut down to the shape indicated, thinner at the middle, to provide a place for the cord connected to the rubber motor. The grooved pulley and the fluted drive wheel at the winding-key end, shown in Fig. 5, are then cut loose; the drive wheel on the other end is cut loose, forming three sections, mounted on the wire axle, one end of which is the winding key. Ratchet wheels, M, are fitted between the ends of the center section and the adjoining pieces, the ratchet wheels being nailed to the center section and soldered to the wire axle. Pawls, U, are fitted to the inside of the two end sections, as indicated in Fig. 1 and in Fig. 5. When the rubber motor is wound up on the drum, the tractor bands are gripped until it is desired to start the tank on its trip. Then the power is communicated from the drum, or center section of the axle, to the drive wheels by means of the ratchet wheels, acting on the pawls.

Mount the hangers F on the center crosspiece D, fitting the axles of the drive wheels into place. Make the weighted flywheel, and mount it on its shaft, as shown, lining it up with the pulley on the rear drive shaft. Fit the supports J and K into place, setting spools for the rubber-motor cord in place, on wire axles. Arrange the belt from the flywheel to the drive shaft, and connect the rubber bands for the rubber motor as shown. Fasten one end in the hook of support J, and pass the winding cord through the spools, and fix it to the drive shaft. The device can then be operated with the fluted drive wheels, bearing on strips of wood for tracks.

The tractor bands N are fitted over the drive wheels, as shown in Fig. 6. They are built up of canvas strips, on which wooden shoes are glued and sewed, as detailed in Fig. 5. The stitches which reinforce the gluing are taken in the order indicated by the numerals. The pilot wheel is 2 in. in diameter, and sharpened at its circumference. Make a metal shell, O, for it, as detailed in Fig. 6. Solder the shell to the double wire, which supports the wheel and gives it a spring tension to take obstructions nicely. The wire is fastened to the crosspiece D, as shown in Fig. 5.

The gun and its mechanism can be made handily before the support E is fixed into place at the front of the crosspiece D. Shape the magazine P from sheet metal, making it 2⁵⁄₈ in. high, as detailed in Fig. 4. Make the gun Q from a piece of sheet metal, as detailed, cutting the metal to the exact dimensions indicated. Mount the magazine and the gun, and arrange the wire hammer R, and the rubber band that holds it. Fit the pulley A into place on its axle, supported by a small block of wood. Belt it to the front drive-wheel axle, as shown in Fig. 5, after the gun support is fastened into place with screws. Make the projectiles of wood, as shown, and the fighting tank is ready to be tested before putting on the armor.

The armor is made of one deck piece, S, Fig. 3, into which the covered turret is set, and two side pieces T, as detailed in Fig. 2. Make one left and one right sidepiece, allowing for the flanges all around, to be bent over and used for riveting or soldering the armor together. The bottom extension on the sidepieces is bent double to form an angle, on which the armor is supported, where it rests on the top of the hangers F. The turret is fitted to the deck by cutting notches along its lower edge, the resulting strips being alternately turned in and out along the point of joining, as shown in Fig. 3. When the armor is completed, it is fitted over the main frame, the gun projecting from the turret. Small pins hold the ends of the armor solid against the ends of the main frame C, so that the armor can be lifted off readily. The various parts of the fighting tank can be painted as desired, care being taken not to injure the points of bearing, on the axles and pulleys, which should be oiled. Silver bronze is a good finish for the exterior of the armor, which may be decorated with a coat of arms.

FIG. 6

Plan and Side Elevation of the Interior Mechanism, with the Armor Removed, and Details of the Metal Fittings, the Ratchets, and the Tractor Bands]

A Neat and Economical Baby Crib Made from a Clothes Basket

A clothes basket on a simple but strong wooden frame, mounted on castors, makes a cradle which is as convenient and sanitary as many which are sold for five times its cost. It is light enough to roll out on the porch without difficulty, and may be padded and fitted with pillows until the most exacting mother is satisfied. The basket and frame should be painted, preferably some light color. The whole cost, not including pads or pillows, should not be over $2.50.--A. Switzer, Denver, Colo.

A Small Rheostat for Experiments and Testing

A rheostat made as shown in the sketch has been used successfully for calibrating a large number of ammeters and wattmeters. One of the general designs suggested will be useful for many other purposes. The dimensions given were used for obtaining a variation of from ¹⁄₂ to 5 amperes with a 6-volt source of electromotive force. For other capacities the proportions may be increased or decreased proportionately. A piece of pine, 7 by 9¹⁄₂ in., forms the base. For resistance wire No. 16 gauge “Climax” was used, but wire of any material which will carry the maximum current without excessive oxidation may be employed instead. Nails support the resistance wire, which should be soldered to the nails to insure good electrical contact. Leads of flexible cord are arranged as shown. These are soldered to the first and last nails in the series. To provide connection between the free ends of the cord and the resistance wire or the nails, 5-ampere test clips are soldered to the cord ends. The teeth of the clip jaws are filed off, and in their stead a short piece of brass wire is soldered to each jaw, as indicated in the detailed view. A nick is filed in each of the brass wires so that they will hold firmly onto the resistance wire or nail. Suspender or display-case clips, suitably modified, may be substituted for the commercial test clips.

In using the device, one clip is moved along the front span. The other is gripped to a nail in the rear row. Sliding the front clip along the span wire insures a fine adjustment of resistance. Gripping the rear clip on the different nails provides the coarse adjustment--R. F. Binney, La Vina, Calif.

* * * * *

¶Glue applied to door-knob screws will prevent them from loosening
easily, yet they may be removed without difficulty.

Roll-Paper Feed for Typewriter

Typewriter paper may be fed from a roll where only one copy is necessary and where maximum speed of production is essential. Sections, not to exceed about 11 in. in length, of the typed paper are torn off as necessary. This practice is followed often in newspaper offices. The roll paper can be purchased at any paper-supply house, cut to the width required by the user. The construction of a roll-feed attachment which may be mounted on any of the standard typewriters will be described.

First make the two uprights. Both are cut from ¹⁄₆-in. sheet brass, as shown. After cutting, heat the pieces to anneal them before bending. A hole is provided for the paper-roll rod in the right-hand upright and a slot in the left-hand one. A rod, threaded on one end and equipped with two nuts, constitutes the paper holder. For a guide plate and cutter, cut a piece of sheet brass, 1¹⁄₂ in. wide and of a length equal to that of the carriage, as detailed in the drawing. Bend it as shown. A ¹⁄₈-in. slot is cut almost the entire length of the guide.

In mounting the holder on the typewriter, the uprights are drilled at the base to engage the two small screws at the side of the carriage back of the roller. The exact location of these holes will vary in machines of the different makes. Next, the uprights are clamped into place with the screws, one at each end of the carriage. Then determine the distance between the arms of the uprights, drill a corresponding hole at each end of the guide-and-cutter plate, and fasten the plate to the uprights with small stove bolts. The roll of paper is placed on the rod and fed between the machine platen and roller as with single sheets. When the article or memorandum being written is finished, the paper is held against the guide plate and the blade of a pocketknife inserted in the slot. Passing the blade the length of the slot cuts off the paper, or it may be torn off at the slot. The end of the paper roll is again fed into the machine, ready for another operation.

Handy Paring Knife Made from Old Hacksaw Blade

With a little work a hacksaw blade, or a portion of one, can be made into a paring knife that will prove very durable because of the excellent quality of the steel. Two pieces of hard wood should be cut into the shapes shown and riveted together with one end of the blade between them. After putting a paper mold about the end of the handle from which the steel projects, melted lead is poured into it, to form a collar that will hold the parts firmly together. The exposed part of the saw can then be ground as desired.

Washing Machine Equipped with Churn Attachment

The owner of a power-driven family washing machine has provided an attachment for it with which he churns cream at a little additional expenditure of energy. A wooden plunger was bolted to the outside of the flywheel and its upper end placed between two rollers set in a metal frame attached to the side of the tub. Enough play was allowed between the rollers to permit the plunger to move up and down freely. A framework large enough to hold a glass fruit jar was attached to the side of the plunger, a thumbscrew being provided in its upper end with which the jar is held firmly in place. As the flywheel revolves, the movement of the plunger thoroughly agitates the contents of the jar.--Dale R. Van Horn, North Loup, Neb.

Treating Closets with Cedar Oil

Apropos of the article in a recent issue of Popular Mechanics Magazine entitled “A Cedar-Lined Oak Chest,” readers who desire the advantages of a cedar-lined box or closet may accomplish it by the use of cedar oil. Painting the interior of a box with this oil will to all intents and purposes convert it into a cedar chest regardless of the kind of wood used. The cost of the oil is not great. A closet treated in the same manner will likewise keep out insects.--Robert E. M. Bain, St. Louis, Mo.

Barnyard Gate is Operated with the Foot

A gate which can be unlatched with the foot has proven a great convenience across a path on a farm where laborers frequently pass with both hands occupied carrying pails. Pivoted to the side of the gate, near its center, a beam, or foot lever, is hung in a vertical position, extending almost to the ground and having a shelf bracket fastened to its upper end. The horizontal arm of the bracket passes beneath a porcelain knob projecting from a pivoted bar that engages the elbow catch. By pushing the vertical beam to one side with the foot the bar is raised above the catch, allowing the gate to swing open. If the gate is properly hung it will close of itself, the elbow catch serving to prevent its being opened again, except when the bar is raised.--T. C. McDowell, Adrian, Michigan.

Improvised Post-Card Projector and Enlarging Camera

BY HARRY MARCELLE

An outfit which may be used for either projecting picture post cards or enlarging photographic negatives was assembled as delineated in the illustration. An ordinary camera, which provides the lens and bellows, is required, in combination with a dark box which can be built in the home workshop. The method of construction is this:

Make a box about 8 in. square out of ¹⁄₂-in. planed soft-wood stock. Nail the sides, but omit, for the present, the top and the bottom. The two openings thus left will be called the front and the back. Mount an 8 by 8 by ¹⁄₂-in. board, D, which constitutes a door, on the back with hinges and provide a hook to hold it shut. Cut a square hole, of the same size as that of the opening in the back of the camera which is to be used, in another 8 by 8-in. piece, E. This will constitute the front board. This front board is so cut that it fits in between the sides of the box instead of on the ends, as does the back. In the top, cut a square hole for ventilation. A hood is provided over this hole to prevent light being thrown forward.

When using the arrangement as a projector or magic lantern two 40-watt tungsten lamps, A, are required. Each lamp is mounted in a porcelain receptacle held on the floor with screws. A lamp cord, one end connecting the two lamps in multiple and the other fitted with an attachment plug, passes through a hole in the floor of the box. Form the two reflectors, B, of 8 by 7-in. bright tinned sheet-iron pieces, each having holes along one of its edges to admit of attachment. The reflectors are bent to a semicircular contour before mounting. The card holder is detailed at C. It is a piece of tinned sheet iron bent to the form shown so that it will hold a post card. A hole is drilled in its center for a screw pivot. It can then be fastened to the center of the back door and can be turned into position for either horizontal or vertical pictures. A washer is inserted on the screw between the holder and the door. The thickness of the camera body having been determined, a slide is fastened to the front board, as diagrammed, to support this body.

Before it can be used as a projector it must be adjusted to operate with the camera of the type and size available. The adjustment, which must be made in a darkened room, having on one of its walls a white screen on which the image will be projected, is effected thus: Remove the back from the camera and place the camera in the slide without extending the bellows. Open the shutter. Insert a card in the holder C. Light the tungsten lamps. Now move the front board, with the camera carried on it, back and forth within the box until the components are in focus, that is, until the most distinct image obtainable is reproduced on the screen. Then, illuminate the previously darkened room and nail the front board in the position thus determined. These adjustments having been made, paint the box, inside and out, a coat of dead black. Everything should be painted black except the reflecting surfaces of the tin reflectors and the incandescent-lamp bulbs. The front board having been fastened, subsequent focusing can be effected by shifting longitudinally the lens board of the camera. The image of any sort of a picture that will fit in the holder can be reproduced. Colored post cards will project in their natural tints.

To make enlargements with the same box, a few minor changes are necessary. When employed for enlargements the tungsten lamps, which are required for projection, are not used. They may, however, remain in the box and can be disconnected from circuit by unscrewing them a few turns. The negative, or film, which is to be enlarged, is held in the opening E. Where a film is to be reproduced, it is held between two pieces of glass which are fastened to the inside of the front board with small clips. If a glass negative is used, the two additional glass plates are unnecessary. If the negative does not fill the opening in the camera, a mask cut from heavy black paper will be required to cut off the light.

The light for the enlargement is furnished by another tungsten lamp mounted in a porcelain receptacle which is screwed to a board which constitutes a base. This light source is moved about in the house until it is directly back of the opening E in the front of the box and until the light is distributed equally over the entire negative. To focus, move the camera backward or forward. While focusing, use a yellow glass, or ray screen, to cover the lens. When focusing has been completed, the shutter is closed and the ray screen removed. Then stop down the lens to bring out detail, and expose.

Changing a Motor-Car Tire without a Jack

It occasionally happens that a motorist fails to have a jack at hand when a tire needs to be changed on the road. The situation is easily met with the aid of a strong board and a couple of blocks or rocks. Driving the desired wheel onto the incline, provided in the manner illustrated, and setting the brakes, a block is placed beneath the axle. The board is then knocked out of the way.--John Peters, Milwaukee, Wis.

Roller Truck for Use in Scrubbing

A little padded platform on wheels takes most of the drudgery away from scrubbing in hotels and office buildings. The platform carries the pail as well as the scrubber, and enables the scrubber to keep dry.--Florence L. Clark, McGregor, Ia.

Economical Use of Wood Alcohol in Small Cooking Stove

A couple eating breakfast and supper in their room used a chafing dish for cooking. A hard alcohol was used for fuel, and the expense seemed too high. So a fuel can was filled with pulverized asbestos pipe covering, and then saturated with wood alcohol. A quart of alcohol lasted about a month.--Charles A. King, Plymouth, N. H.

Attractive Table Stands for Hot Dishes

Attractive stands which will preserve the dining table from injuries, or heat marks made by hot dishes, can be easily made from thin pieces of board cut oblong or oval. After the board has been cut the proper size, cleats are fastened to the underside to which billiard-cue tips are attached to serve as supports. The stand should be varnished and waxed to match the table.--George L. Furse, St. Louis, Mo.

Cord Used as Spacer for Curtain Rings

To make the curtain rings space automatically along the curtain pole, tie a cord from one ring to the next, spacing the rings uniformly. Or the cord may be attached at uniform distances to the curtain. A pull at the edge of the curtain will space the rings evenly every time.--Frank L. Matter, Portland, Ore.

Device for Packing Earth in Transplanting

When tomato or cabbage plants are to be set out in considerable numbers, the simple implement shown here makes stooping over to press the dirt about the plants unnecessary. After a row of plants has been set in dibble holes and watered, the soil can be packed about their roots quickly while one is standing upright. The jaws of the device are actuated by means of the hinged lever.--A. S. Thomas, Amherstburg, Ont.

Cleat and Pulley Fastenings to Adjust Clothesline

The following kink will relieve the housewife of the trouble of sagging clotheslines, and hubby of constantly being asked to tighten up the line. The cost should not be over 25 cents, as all that is needed is a pulley cleat and hook, all of which may be had at any ten-cent store. When the line gets slack, it is pulled tight through the pulley and tightened up in the cleat.--S. H. Johnson, Westville, Conn.

Convenient Type of Mail Box for Home Use

A person having a mail box set flush in the outside wall of his home can, with a little alteration, make it accessible from inside the house: After removing the back side of the box a tin extension should be soldered to the box giving it sufficient length to reach through the wall in which an opening of the proper size has been cut. The enlarged container is completed by adding a glass door to the inner end which enables one to ascertain its contents at a glance.--A. Pertle, Chicago, Ills.

Block Plane Converted for Use on Circular Work

Few amateur craftsmen can afford to own a circular plane, yet this tool is decidedly necessary for such round work as table tops, half-round shelves, segments, and the like. Any ordinary block plane will accomplish such work if equipped as illustrated. A piece of half-round hard wood is cut the width of the plane and attached with countersunk machine screws, as indicated. The block elevates the rear end of the plane, causing it to follow the curve of the work on which it is used.

Pressure Spray Made of Old Oilcan

In making a spraying outfit for garden use, or similar purposes, a 3 or 5-gal. kerosene can and tire pump may be satisfactorily employed. The latter is attached rigidly at the rear of the container with iron straps, as shown. A ball check valve is fitted in the top of the receptacle and connection is made between it and the pump with the pump hose. A 6-ft. length of ¹⁄₄-in. rubber tubing is wired to the drain cock. An 8-in. piece of ¹⁄₄-in. brass pipe is filed down and wired in the spray end of the hose to serve as a nozzle.--P. P. Avery, Garfield, N. J.

Keeping Tools Bright and Free from Rust

Bright-finished tools can be preserved against rust by coating with linseed oil, and allowing the oil to dry as a film. If more body is desired, oxide of iron, very finely powdered, should be mixed with the oil. Another antirust coating is made by dissolving ¹⁄₂ oz. camphor in 1 lb. melted lard. The mixture is skimmed, and fine graphite added to make an iron color. Clean the tools and smear with this mixture. Let the tools stand 24 hours, and rub clean with soft cloth.

A good method of removing rust is to cover the metal parts with sweet oil, rubbing it in well. Let stand 48 hours; then rub with finely powdered, unslaked lime. Next immerse the article for a few seconds in a solution of ¹⁄₂ oz. potassium cyanide in a wine glass of water. Then clean with a paste of potassium cyanide, castile soap, whiting, and water, using a toothbrush. Potassium cyanide is a strong poison, and should be used carefully.--E. Standiford, Youngstown, Ohio.

Repairing Leaks in Pipes

Frequently a cast or malleable-iron pipe fitting will leak through its side, the water oozing, drop by drop, from a pinhole--ordinarily due to a sand hole in the casting. Sometimes the leak can be stopped by hammering the affected spot with the ball end of a hammer. If this fails, it is necessary to replace the fitting. Where the leak is around a thread, screwing the pipe or fitting tighter constitutes the only, and usually effective, corrective.--L. A. Merton, St. Louis, Mo.