How to Make a Hydrometer - Easy Science Projects

How to Make a Hydrometer - Easy Science Projects

The hydrometer is an instrument used in determining the specific gravity of a liquid, such as acids, etc.
The specific gravity of any material is the ratio of the weights of equal volumes of the material and water. Thus if a pint of acid weighs 1.2 times a pint of water, its specific gravity is said to be 1.2.
A very simple and inexpensive hydrometer, similar to the one shown in the sketch, may be easily constructed, and will give quite satisfactory results, if the scale on the instrument is carefully marked when it is calibrated.
How to Make a Hydrometer
Purchase from the local druggist or doctor two test tubes, one large enough to contain the other, as shown. The smaller tube is to form the hydrometer proper, while the larger one is to serve as a containing vessel in which the liquid to be tested is placed. The large tube should be mounted in a vertical position, by placing it in a hole bored in a small block of wood, or a suitable metal or wooden frame may be made that will accommodate one or more tubes.
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The small tube is loaded at the lower end with a quantity of shot, or other heavy metal, in such a way that it will stand in a vertical position when it is placed in a vessel of water. The amount of the loading will depend upon whether the hydrometer is to be used in determining the specific gravity of liquids heavier or lighter than water. If the liquids are heavier than water, the loading should be such that the tube is almost entirely immersed when placed in water; if lighter, only sufficient loading should be used to make the tube stand upright in water. After the amount of loading has been determined it should be fastened in place by means of a small quantity of calcined plaster. A small cork should now be placed in the open end of the tube, and the tube sealed by coating the end with shellac, or melting a small quantity of resin or sealing wax over the top of the cork with a hot soldering iron.

Now place in the large tube a quantity of as pure water as can be obtained—fresh rain water will answer very well and distilled water still better. Immerse the small tube in the water in the large tube and allow it to come to rest. Make a small mark on the small tube with a file, level with the surface of the water in the large tube. If the hydrometer is placed in a liquid lighter than water and allowed to float, the mark made on the tube will always be below the surface of the liquid in which the instrument is placed, and the mark will be above the surface of the liquid when the liquid is heavier than water.

The hydrometer may be calibrated by making use of a hydrometer borrowed from the druggist or doctor. The two hydrometers should be immersed in the same liquid and the tube of the newly made instrument marked to correspond with the markings on the borrowed instrument. If the liquid is heavier than water to start with, its specific gravity can be reduced by adding water, and as the water is added the hydrometers will both rise.

Excerpt from the book:
THE BOY MECHANIC - BOOK 2
1000 THINGS FOR BOYS TO DO
HOW TO CONSTRUCT DEVICES FOR WINTER SPORTS, MOTION-PICTURE CAMERA, INDOOR GAMES, REED FURNITURE, ELECTRICAL NOVELTIES, BOATS, FISHING RODS, CAMPS AND CAMP APPLIANCES, KITES AND GLIDERS, PUSHMOBILES, ROLLER COASTER, FERRIS WHEEL AND HUNDREDS OF OTHER THINGS WHICH DELIGHT EVERY BOY WITH 995 ILLUSTRATIONS PUBLISHED 1915, BY H. H. WINDSOR CHICAGO  POPULAR MECHANICS CO. PUBLISHERS

How to Make a Galvanometer - Easy Science Projects

How to Make a Galvanometer - Easy Science Projects

A galvanometer is an instrument used to detect the presence of an electrical current in a circuit or to measure the value of the current in amperes. The operation of practically all galvanometers is based upon the same principle, and they differ chiefly in mechanical construction and the relative arrangement of their different parts.

A very simple galvanometer, that will give quite satisfactory results, under favorable conditions, may be constructed as follows: Turn from a piece of hard wood a ring having dimensions corresponding to those given in the cross section, Fig. 1. Fill the groove in this ring to within 1/8 in. of the top with No. 18 gauge double-cotton-covered copper wire, insulating the different layers from each other by means of a layer of good bond paper. The winding may be started by drilling a small hole through the side of the groove, as close to the bottom as possible, and allowing about 6 in. of the wire to protrude through it. The outside end may be terminated in a similar manner, and the two ends should be on the same side of the ring, or as near each other as possible. A protecting covering of bookbinder's paper is placed over the winding and the completed ring given a coat of shellac. The electric current to be detected or measured is to pass around the winding of this coil and produce an effect upon a compass needle mounted in its center. In order that the current may produce a maximum effect upon the needle, the coil should be mounted in a vertical position.
How to Make a Galvanometer

The Wood Ring for the Coil and Its Holding Stirrup (Fig. 1, Fig. 2)

The base upon which the ring is to be mounted may be cut from some 1/2-in. hard wood. It should be circular in form and about 5 in. in diameter, and have its upper edge rounded off and shellacked to improve its appearance. The ring is mounted in a vertical position on this base, which may be done as follows: Cut a flat surface on each of the flanges of the ring so that it will stand in a vertical position and the terminals of the winding will be as near as possible to the surface upon which the ring rests. Then form a stirrup from some thin sheet brass, similar to that shown in Fig. 2, so that it will fit tightly over the ring and its outwardly projecting ends will rest upon the base of the instrument. Small wood screws are used in fastening the stirrup to the base. The fastening may be made more secure by cutting a groove across the inside of the ring for the stirrup to fit in, Fig. 3, thus preventing the possibility of the ring moving through the stirrup. Two holes should be drilled in the base for the terminals of the winding to pass through, and it would be best to cut two grooves in the side of the ring for these wires so as to prevent their coming into contact with the metal stirrup. Two back-connected binding posts, A and B, Fig. 3, are mounted on the base and the ends of the winding attached to them. The wires should be placed in grooves cut in the under side of the base, and the screws used in fastening the binding posts should be countersunk.
Galvanometer as It is Used to Detect the Presence of an Electrical Current (Fig. 3)
Galvanometer as It is Used to Detect the Presence of an Electrical Current (Fig. 3)

A short compass needle is then mounted on a suitable supporting pivot in the center of the coil. This compass needle will always come to rest in an approximate north and south position when it is acted upon by the earth's magnetic field alone. If now the plane of the coil be placed in such a position that it is parallel to the direction of the compass needle (no current in the coil), the magnetic field that will be produced when a current is sent through the winding will be perpendicular to the magnetic field of the earth and there will be a force, due to this particular current, tending to turn the compass needle around perpendicularly to its original position. There will be a deflection of the needle for all values of current in the coil, and this deflection will vary in value as the current in the coil varies. The mere fact that the compass needle is deflected due to a current in the coil gives a means of detecting a current in any circuit of which the coil is a part, and the degree of this deflection affords a means of measuring the current, the value of the different deflections in terms of the current in the coil having been experimentally determined by sending a known current through the coil and noting the positions of the compass needle for each value of current used.

In order to determine the deflection of the needle, a scale, C, Fig. 3, must be mounted directly under the compass needle and a pointer, D, attached to the compass needle so that any movement of the needle results in an equal angular displacement of the pointer. The compass needle, E, should be short and quite heavy, say, 5/8 in. in length, 1/16 in. in thickness and 1/4 in. in width at its center, and tapering to a point at its ends. It should be made of a good grade of steel, tempered and then magnetized by means of a powerful electromagnet. The reason for making the compass needle short is that it will then operate in practically a uniform magnetic field, which exists only at the center of the coil. On account of the needle being so short and in view of the fact that it comes to rest parallel to the coil for its zero position, it is best to use a pointer attached to the needle to determine its deflection, as this pointer can be made much longer than the needle, and any movement of the needle may be more easily detected, as the end of the pointer moves through a much larger distance than the end of the needle, and since it may be attached to the needle, at right angles to the needle's axis, the end of the pointer will be off to one side of the coil and its movement may be easily observed. The pointer should be made of some nonmagnetic material, such as aluminum or brass, and it should be as long as it may be conveniently made. A suitable box with a glass cover may be provided in which the needle, pointer and scale may be housed. The construction of this box will be left entirely to the ingenuity of the one making the instrument.
The Electric Circuit, Showing Connections for Finding the Value of a Current in Calibrating (Fig. 4)
The Electric Circuit, Showing Connections for Finding the Value of a Current in Calibrating (Fig. 4)

In order to use this instrument as an ammeter, it will be necessary to calibrate it, which consists in determining the position of the pointer for various values of current through the coil. It will be necessary to obtain the use of a direct-current ammeter for this purpose. The winding of the galvanometer, ammeter, battery and a variable resistance of some kind should [391] all be connected in series as shown in the diagram, Fig. 4. Allow the compass needle to come to rest under the influence of the earth's magnetic field and then turn the coil into such a position that it is as nearly parallel with the needle as possible. This corresponds to the zero position, and the instrument must always be in this position when it is used. The position of the ends of the pointer is now marked on the scale for different values of current, first with the current in one direction and then in the opposite direction. The deflection of the needle will, of course, reverse when the current is reversed.

The effect produced by any current upon the compass needle can be changed by changing the number of turns in the coil. In measuring a large current, a few turns of large wire would be required, and in measuring a small current, a large number of turns of small wire could be used. In other words, the size of the wire will depend upon the current it is to carry and the number of turns in the coil will depend upon the magnetic effect the current is to produce, which is proportional to the product of the number of turns and the current, called the ampere-turns.

Excerpt from the book:
THE BOY MECHANIC - BOOK 2
1000 THINGS FOR BOYS TO DO
HOW TO CONSTRUCT DEVICES FOR WINTER SPORTS, MOTION-PICTURE CAMERA, INDOOR GAMES, REED FURNITURE, ELECTRICAL NOVELTIES, BOATS, FISHING RODS, CAMPS AND CAMP APPLIANCES, KITES AND GLIDERS, PUSHMOBILES, ROLLER COASTER, FERRIS WHEEL AND HUNDREDS OF OTHER THINGS WHICH DELIGHT EVERY BOY WITH 995 ILLUSTRATIONS PUBLISHED 1915, BY H. H. WINDSOR CHICAGO  POPULAR MECHANICS CO. PUBLISHERS

How to Make a Rheostat - DIY Projects

How to Make a Rheostat

In operating small motors there is as a rule no means provided for regulating their speed, and this often is quite a disadvantage, especially in the case of toy motors such as used on miniature electric locomotives. The speed, of course, can be regulated by changing the number of cells of battery by means of a special switch, but then all the cells are not used the same amount and some of them may be completely exhausted before the others show any appreciable depreciation. If a small transformer is used with a number of taps taken off the secondary winding, the voltage impressed upon the motor, and consequently the speed, can be changed by varying the amount of the secondary winding across which the motor is connected.
Diagram Showing the Connections for a Small Motor Where a Rheostat Is in the Line (Fig. 1)
 Diagram Showing the Connections for a Small Motor Where a Rheostat Is in the Line (Fig. 1)

But in both these cases there is no means of varying the speed gradually. This can, however, be accomplished by means of a small rheostat placed in series with the motor. The rheostat acts in an electrical circuit in just the same way a valve does in a hydraulic circuit. It consists of a resistance, which can be easily varied in value, placed in the circuit connecting the motor with the source of electrical energy. A diagram of the rheostat is shown in Fig. 1, in which A represents the armature of the motor; B, the field; C, the rheostat, and D, the source of electrical energy.
When the handle E is in such a position that the maximum amount of resistance is in circuit there will be a minimum current through the field and armature of the motor, and its speed will be a minimum. As the resistance of the rheostat is decreased, the current increases and the motor speeds up, reaching a maximum value when the resistance of the rheostat has been reduced to zero value. Such a rheostat may be used in combination with a special switch F., as shown in. Fig. 2. The switch gives a means of varying the voltage and the rheostat takes care of the desired changes in speed occurring between those produced by the variations in voltage.
Diagram of a Small Motor Where a Rheostat and Switch Are in the Line (Fig. 2)
Diagram of a Small Motor Where a Rheostat and Switch Are in the Line (Fig. 2)

A very simple and inexpensive rheostat may be constructed as follows: Procure a piece of thin fiber, about 1/16 in. thick, 1/2 in. wide and approximately 10 in. long. Wind on this piece of fiber, after the edges have all been smoothed down, a piece of No. 22 gauge cotton-covered resistance wire, starting about 1/4 in. from one end and winding the various turns fairly close together to within 1/4 in. of the other end. The ends of the wire may be secured by passing them through several small holes drilled in the piece of fiber, and should protrude 3 or 4 in. for connecting to binding posts that will be mounted upon the base of the rheostat.

Now form this piece of fiber into a complete ring by bending it around some round object, the flat side being toward the object. Determine as accurately as possible the diameter of the ring thus formed and also its thickness. Obtain a piece of well seasoned hard wood, 1/2 in. thick and 4-1/2 in. square. Round off the corners and upper edges of this block and mark out on it two circles whose diameters correspond to the inside and outside diameters of the fiber ring. The centers of these circles should be in the [394] center of the block. Carefully saw out the two circles so that the space between the inside and outside portions will just accommodate the fiber ring. Obtain a second piece of hard wood, 1/4 in. thick and 4-3/4 in. square, round off its corners and upper edges and mount the other pieces upon it by means of several small wood screws, which should pass up from the under side and be well countersunk. Place the fiber ring in the groove, but, before doing so, drill a hole in the base proper for one end of the wire to pass through. Two small back-connected binding posts should be mounted in the corners. One of these should be connected to the end of the winding and the other to a small bolt in the center of the base that serves to hold the handle or movable arm of the rheostat in place. These connecting leads should all be placed in grooves cut in the under side of the base.
A Cross Section of the Rheostat, Showing the Connections through the Resistance (Fig. 3)
A Cross Section of the Rheostat, Showing the Connections through the Resistance (Fig. 3)

The movable arm of the rheostat may be made from a piece of 1/16-in. sheet brass, and should have the following approximate dimensions: length, 2 in.; breadth 1/2 in. at one end, and 1/4 in. at the other. Obtain a 1/8-in. brass bolt, about 1 in. long, also several washers. Drill a hole in the larger end of the piece of brass to accommodate the bolt and also in the center of the wooden base. Countersink the hole in the base on the under side with a 1/2-in. bit to a depth of 1/4 in. On the under side of the piece of brass, and near its narrow end, solder a piece of thin spring brass so that its free end will rest upon the upper edge of the fiber ring. A small handle may be mounted upon the upper side of the movable arm. Now mount the arm on the base by means of the bolt, placing several washers between it and the upper surface of the base, so that its outer end will be raised above the edge of the fiber ring. Solder a short piece of thin brass to the nut that is to be placed on the lower end of the bolt, and cut a recess in the countersunk portion of the hole in the base to accommodate it. When the bolt has been screwed down sufficiently tight a locknut may be put on, or the first nut soldered to the end of the bolt. If possible, it would be best to use a spring washer, or two, between the arm and base.

The insulation should now be removed from the wire on the upper edge of the fiber ring with a piece of fine sandpaper, so that the spring on the under side of the movable arm may make contact with the winding. The rheostat is now complete with the exception of a coat of shellac. A cross-sectional view of the completed rheostat is shown in Fig. 3.

Excerpt from the book:
THE BOY MECHANIC - BOOK 2
1000 THINGS FOR BOYS TO DO
HOW TO CONSTRUCT DEVICES FOR WINTER SPORTS, MOTION-PICTURE CAMERA, INDOOR GAMES, REED FURNITURE, ELECTRICAL NOVELTIES, BOATS, FISHING RODS, CAMPS AND CAMP APPLIANCES, KITES AND GLIDERS, PUSHMOBILES, ROLLER COASTER, FERRIS WHEEL AND HUNDREDS OF OTHER THINGS WHICH DELIGHT EVERY BOY WITH 995 ILLUSTRATIONS
PUBLISHED 1915, BY H. H. WINDSOR CHICAGO
POPULAR MECHANICS CO. PUBLISHERS

How to Make an Anemometer for a Science Project - An Electric Anemometer By Wm. H. Dettman

How to Make an Anemometer for a Science Project - An Electric Anemometer By Wm. H. Dettman

The construction of this instrument is so simple that any amateur can make one and if accurate calibrations are desired, these can be marked by comparison with a standard anemometer, while both are placed in the wind.

The Indicator

The case of the indicator is built of thin wood—the material of an old cigar box will do—9 in. long, 6 in. wide and 1-1/2 in. deep. If cigar-box material is used, it must first be soaked in warm water to remove the paper. If a cover is to be used on the box, a slot, on an arc of a circle, must be cut through it to show the scale beneath. The arc is determined by the length of the needle from a center over the axis on which the needle swings. When the box is completed, smooth up the outside surface with fine sandpaper and give it a coat of stain.
The core of the magnet is made by winding several layers of bond paper around a pencil of sufficient size to make an inside diameter of slightly over 1/4 in., and a tube 2 in. long. Each layer of the paper is glued to the preceding layer.
Two flanges or disks are attached to the tube to form a spool for the wire. The disks are cut from thin wood, 1-1/4 in. square, and a hole bored through their centers so that each will fit on the tube tightly. One of them is glued to one end of the tube and the other fastened at a point 1/2 in. from the opposite end. The space between the disks is filled with seven layers of No. 22 gauge insulated magnet wire, allowing sufficient ends of the wire to project for connections. The finished coil is located in the box, as shown at A, Fig. 1.
The Indicator Box with Coil, Needle and Scale, as It is Used in Connection with the Anemometer (Fig. 1)

The core for the coil is cut from a piece of 1/4-in. iron rod, 1-1/4 in. long, and a slot is cut in each end, 1/4 in. deep, into which brass strips are inserted and soldered, or otherwise fastened. The strips of brass are 3/16 in. wide, one 1-1/2 in. long and the other 3/4 in. Two 1/16 in. holes are drilled in the end of the long piece, and one 1/16 in. hole in the end of the short piece. The complete core with the brass ends is shown in Fig. 2.


The Metal Core for the Coil... (Fig. 2)

...and the Bearing Block for the Axis of the Needle (Fig. 3)

The needle B, Fig. 1, is made of a copper or brass wire, about 6 in. long, and is mounted on an axis at C. The detail of the bearing for the axis is shown in Fig. 3. The axis D is a piece of wood fitted in the U-shaped piece of brass and made to turn on brads as bearings, the center being pierced to receive the end of the needle. After locating the bearing for the axis C, Fig. 1, it is fastened in place so that the upper end or pointer of the needle will travel over the scale. The needle is then attached to the bearing after having been passed through the inner [368] hole of the longer brass strip of the core, and the coil is fitted with the core in the manner shown at D. A light brass coil spring is attached to each end of the core, as shown at E and F, the latter being held with a string, G, whose end is tied to a brad on the outside of the box, for adjustment. A better device could be substituted by attaching the end of the spring F to a nut and using a knurled-head bolt passed through the box side. One of the wires from the coil is attached to a push button, H, to be used when a reading of the instrument is made. The connections for the instrument consist of one binding post and a push button.

The Anemometer as It is Mounted on a Standard Similar to a Small Windmill Weather Vane (Fig. 4)

The Anemometer

The anemometer resembles a miniature windmill and is mounted on top of a building or support where it is fully exposed to the air currents. It differs from the windmill in that the revolving wheel is replaced by a cupped disk, A, Fig. 4, fitted with a sliding metal shaft, B, which is supported on crosspieces, CC, between the main frame pieces DD. The latter pieces carry a vane at the opposite end. The frame pieces are 1/2 in. thick, 2-1/4 in. wide and 36 in. long, and the crosspieces have the same width and thickness and are 4 in. long.

(Fig. 5)
A variable-resistance coil, E, is made as follows and fastened in the main frame. The core of this coil is a piece of wood, 2 in. square and 4 in. long, and wound with No. 18 gauge single-wound cotton-covered german-silver wire. The winding should begin 1/4 in. from one end of the core and finish 1/4 in. from the other, making the length of the coil 3-1/2 in. The ends of the wire are secured by winding them around the heads of brads driven into the core. A small portion of the insulation is removed from the wire on one side of the coil. This may be done with a piece of emery cloth or sandpaper. A sliding spring contact, F, is attached to the sliding shaft B, the end of which is pressed firmly on the bared portion of the wire coil. One end of a coil spring, which is slipped on the shaft between the pieces CC, is attached to the end crosspiece, and the other end is fastened to the sliding shaft so as to keep the shaft and disk out, and the flange H against the second crosspiece, when there is no air current applied to the disk A. The insulation of the standard upon which the anemometer turns is shown in Fig. 5. The standard J is made of a piece of 1/2-in. pipe, suitably and rigidly attached to the building or support, and the upper end, around which the anemometer revolves to keep in the direction of the air currents, is fitted with a plug of wood to insulate the 1/4-in. brass rod K. A bearing and electric-wire connection plate, L, is made of brass, 1/8 in. thick, 2 in. wide and 4 in. long. The bearing and connection plate M are made in a similar manner. The surface of the holes in these plates, bearing against the pipe J and the brass rod K, make the two connections for the wires from the variable-resistance coil E, Fig. 4, located on the main frame, to the wire connections between the two instruments. These wires should be weather-proof, insulated, attached as shown, and running to and connecting the indicator with the anemometer at NN, Fig. 1.
Two or more dry cells must be connected in the line, and when a reading is desired, the button H, Fig. 1, is pushed, which causes the current to flow through the lines and draw the magnet core D in the coil, in proportion to the magnetic force induced by the amount of current passing through the resistance in the coils on E, Fig. 4, from the contact into which the spring F is brought by the wind pressure on the disk A.

Excerpt from the book:
THE BOY MECHANIC - BOOK 2
1000 THINGS FOR BOYS TO DO
HOW TO CONSTRUCT DEVICES FOR WINTER SPORTS, MOTION-PICTURE CAMERA, INDOOR GAMES, REED FURNITURE, ELECTRICAL NOVELTIES, BOATS, FISHING RODS, CAMPS AND CAMP APPLIANCES, KITES AND GLIDERS, PUSHMOBILES, ROLLER COASTER, FERRIS WHEEL AND HUNDREDS OF OTHER THINGS WHICH DELIGHT EVERY BOY WITH 995 ILLUSTRATIONS
PUBLISHED 1915, BY H. H. WINDSOR CHICAGO
POPULAR MECHANICS CO. PUBLISHERS

How to Keep Birds Away From Garden - A Garden-Bed Scarecrow

How to Keep Birds Away From Garden -  A Garden-Bed Scarecrow

A very neat and successful scarecrow for garden beds can be made as follows: A number of corks are procured, and a feather is stuck in each end of them, as shown. These are tied to a string, spacing them from 1 to 2 ft. apart, and the string is hung over the beds. The slightest breeze will keep them fluttering, and no bird will come to rest on the beds.
The Fluttering Feathers Attached to the String with Corks Scare the Birds Away

—Contributed by M. T. Canary, Chicago.

Excerpt from the book:
THE BOY MECHANIC - BOOK 2
1000 THINGS FOR BOYS TO DO
HOW TO CONSTRUCT DEVICES FOR WINTER SPORTS, MOTION-PICTURE CAMERA, INDOOR GAMES, REED FURNITURE, ELECTRICAL NOVELTIES, BOATS, FISHING RODS, CAMPS AND CAMP APPLIANCES, KITES AND GLIDERS, PUSHMOBILES, ROLLER COASTER, FERRIS WHEEL AND HUNDREDS OF OTHER THINGS WHICH DELIGHT EVERY BOY WITH 995 ILLUSTRATIONS
PUBLISHED 1915, BY H. H. WINDSOR CHICAGO
POPULAR MECHANICS CO. PUBLISHERS

How to Make a Secret Compartment in Ordinary Table Drawer

How to Make a Secret Compartment in Ordinary Table Drawer

It is frequently desired to have some handy place for storing valuables where there is but little chance of discovering them. Secret drawers in tables usually require special and expensive changes, but with only a few simple changes on a regular drawer of any ordinary table, a secret compartment can be made which is as secure as can ordinarily be figured on, outside of a steel safe.
Having chosen the desired table, a partition should be placed across the entire back part of the drawer, allowing for necessary space in the secret compartment. This partition should resemble the real back of the drawer as closely as it is possible to make it.
The compartment must not be too wide, for the resulting small width of the front part of the drawer might then arouse suspicion.
On the lower side of the secret compartment a strip of wood, A, should be attached with a screw, as shown in Fig. 1, allowing sufficient looseness so the strip may be turned end for end when necessary. With the strip set as shown, it will strike the front side B of the table when the drawer is pulled out, leaving the secret compartment still hidden. In order to expose this, it will be necessary to turn the strip, as shown in Fig. 2, when the drawer can be pulled out to its full length.


Two Positions of the Strip for Holding, or Giving Access to, the Secret Part, and a Hinged Strip (Fig. 1, Fig. 2, Fig. 3)

It being necessary that the strip A be as long as the secret compartment is wide, to fully expose this, there may be cases where the drawer is not wide enough to allow the strip A to turn around. In that case the strip can be hinged to the back of the drawer as shown in Fig. 3. When it is hanging down, as shown by the dotted outline, the drawer may be pulled out to its full extent.
When it is desired to lock the secret compartment, the hinged strip must be swung up in position, and fastened. An ordinary thumbscrew or eye can be used which, by a turn or two, will either release it or fasten it in place.

—Contributed by Paul Durst, Detroit, Mich.
Excerpt from the book:
THE BOY MECHANIC - BOOK 2
1000 THINGS FOR BOYS TO DO
HOW TO CONSTRUCT DEVICES FOR WINTER SPORTS, MOTION-PICTURE CAMERA, INDOOR GAMES, REED FURNITURE, ELECTRICAL NOVELTIES, BOATS, FISHING RODS, CAMPS AND CAMP APPLIANCES, KITES AND GLIDERS, PUSHMOBILES, ROLLER COASTER, FERRIS WHEEL AND HUNDREDS OF OTHER THINGS WHICH DELIGHT EVERY BOY WITH 995 ILLUSTRATIONS
PUBLISHED 1915, BY H. H. WINDSOR CHICAGO
POPULAR MECHANICS CO. PUBLISHERS