CHAPTER XIX MINIATURE LIGHTING

CHAPTER XIX MINIATURE LIGHTINGMiniature lighting is a field of many interesting possibilities for the young experimenter. Any labor expended along this line will result in something far more useful from a practical standpoint than almost any of the other things described in this book.Miniature lights, operated from batteries, may be used in various ways; to light dark corners, hallways, or other places where a light is often temporarily wanted without the accompanying danger and nuisance of matches or kerosene lamps.Miniature lighting has only been made practical by the tungsten filament lamp. The filament, or wire inside the globe, which becomes hot and emits the light when the current is turned on, is made oftungstenin a tungsten lamp. In the earlier lamps, it was made of carbon. The carbon lamp is now seldom used and is highly inefficient when compared to the tungsten.A Carbon Lampconsumes about three and one-half watts of current for each candle-power of light, whereas a small tungsten lamp uses only about one watt per candle-power small tungsten lamp uses only about one watt per candle-power. The tungsten lamp is therefore three times as efficient as a carbon lamp, and when used on a battery of equal voltage it is possible to obtain the same amount of light with one-third of the current that would be required by a carbon lamp.Fig. 281.—Miniature Carbon Battery Lamp.Fig. 281.—Miniature Carbon Battery Lamp.Carbon lamps similar to that shown in Figure 281 are made in a number of different voltages. The lowest voltage that it is practically possible to make a carbon lamp for is three and one-half. A three-and-one-half volt carbon lamp is designed to be operated on small dry cells such as flashlight batteries. The E. M. F. of a dry cell is about one and one-half volts, but when three small dry cells of the flashlight type are connected in series and used to operate a lamp, their voltage "drops," and the available E. M. F. is only about three and one-half volts.Four-volt carbon lamps are intended to be operated on large dry batteries or wet cells because they do not lose their voltage as quickly as small dry cells. The table below gives the voltage and candle-power of the various small carbon lamps which are carried in stock by most electrical dealers or supply houses:MINIATURE CARBON BATTERY LAMPS3.5 volts for flashlight batteries4 volts. 2 candle-power5.5 volts for flashlight batteries6 volts. 2 candle-power6 volts. 4 candle-power8 volts. 4 candle-power10 volts. 6 candle-powerTungsten Lampsare made for voltages as low as one and one-half, and will light on one cell of dry battery. The range of voltages is quite wide and varied. A few of the most common sizes are given below:MINIATURE TUNGSTEN BATTERY LAMPS1.5 volts. for one dry cell2.5 volts. for two-cell flashlight battery2.8 volts. for two-cell flashlight battery3.5 volts. for three-cell flashlight battery3.8 volts. for three-cell flashlight battery4 volts. 4 candle-power6 volts. 2 candle-power6 volts. 4 candle-power6 volts. 6 candle-power6 volts. 8-10-12-16-20-24 candle-powerFig. 282.—Miniature Tungsten Battery Lamp.Fig. 282.—Miniature Tungsten Battery Lamp.To find the approximate amount of current drawn from a battery by a tungsten lamp, divide the candle-power by the voltage and the result will be the current in amperes. For example, a 6 v. 2 c. p. lamp will require, 2 divided by 6, or one-third of an ampere.Six-volt tungsten lamp giving a light greater than six candle-power are only used on storage batteries and are employed principally for automobile lighting.The filament of a tungsten lamp is much longer than that of a carbon lamp and is usually in the form of a spiral or helix, as shown in Figure 282.The bases of battery lamps, the base being the lower portion of the lamp, which is made of brass and fits into a socket or receptacle, are made in three different styles:miniature,candelabra, andEdiswan.Fig. 283.—Lamps fitted respectively with Miniature, Candelabra, and Ediswan Bases.Fig. 283.—Lamps fitted respectively with Miniature, Candelabra, and Ediswan Bases.The miniature and candelabra bases have a threaded brass shell on the outside and a small brass contact-button on the bottom. They are similar except in respect to size. The miniature base is smaller than the candelabra. The Ediswan base is a plain brass shell having two pins on the side and two contacts on the bottom. This type of base is only used in this country on automobiles. The miniature and the candelabra bases are standard for battery lighting. The miniature base has many advantages over the candelabra for the young experimenter, and should be adopted in making any of the apparatus described in this chapter. These three bases are shown in Figure 283.Fig. 284.—Miniature Flat-Base Porcelain Receptacle.Fig. 284.—Miniature Flat-Base Porcelain Receptacle.In order to form a good electrical connection between the lamp and the power wires some sort of a receptacle or socket is necessary. The most common arrangement for this purpose is the miniature flat-base porcelain receptacle shown in Figure 284. This type of receptacle is used in places where it can be permanently fastened in position with two small screws.Fig. 285.—Weather-proof and Pin-Sockets.Fig. 285.—Weather-proof and Pin-Sockets.The devices shown in Figure 285 are known respectively as a porcelain weather-proof socket and a pin-socket. Sockets similar to the weather-proof socket are also made of wood. The weather-proof sockets are used in places where the light is to be exposed out-of-doors, as for instance on a porch. The small metal parts are sealed in the porcelain and entirely protected.The pin-sockets and the wooden sockets are used principally on Christmas trees or in decorative outfits where lamps are hung in festoons. The flat-base receptacle, the pin-socket, and also the wooden socket will be found very useful in making the apparatus described farther on in this chapter.The Wiresused to carry the current in a miniature lighting system may be of the sort known asannunciatororofficewire if the wires are to be run entirely indoors. The wire should not be smaller than No. 16 B. & S. gauge. When the wires are run outdoors, on a porch, or in some other place exposed to the weather, the wire used should be rubber-covered. Hanging lights or lights intended to be adjustable should be connected with "flexible conductor." This is made of a number of very fine wires braided together and insulated with silk. The wires used in a lighting system should not in any case be longer than it is necessary to have them. When a battery is connected to a system of wires it is found that the voltage at the end of the wires is much lower than at a point near the battery. This is called voltage "drop," and is much greater as the wires grow longer. A light placed at the end of two very long wires will not burn as brightly as it would if connected to the same battery by means of short wires.Switchescan be made by following the suggestions given in Chapter VII. Suitable switches can be purchased for a few cents at a most any electrical house and will prove very much neater and efficient. They should preferably be of any of the types shown in Figure 286.The Batteriesused for miniature lighting may be made up of storage cells, dry cells or carbon cylinder cells. Storage cells will prove the most satisfactory, provided that the experimenter has some convenient means of recharging them or of having them recharged. Storage cells will be found of especial value wherever it is desirable to operate several lights from one battery.Carbon cylinder cells are only suitable where one cell is to be operated at a time. If more than one is used, the battery is liable to become polarized and the lamps will not burn brightly. Carbon cylinder batteries are very inexpensive to renew, and will be found the cheapest method of lighting a small tungsten lamp.Fig. 286.—Types of Battery Switches suitable for Miniature Lighting.Fig. 286.—Types of Battery Switches suitable for Miniature Lighting.If lamps requiring more than two amperes are to be operated on dry cells, the latter should be connected in series-multiple, as shown in Figure 69. Two sets of dry cells connected in series-multiple will give more than twice the service of a single set.Lamps may be connected either in multiple or in series, provided that the proper voltages of both battery and lamps are used.When they are to be connected in multiple, the voltage of the lamps should be the same as that of the battery. When they are to be used in series, the voltage of the lamps multiplied by the number used should equal the voltage of the battery. For example, suppose that you wish to use a number of six-volt lamps on a six-volt storage battery. In that case they must be connected in multiple. But if it should be that the lamps are only two-volt lamps and you wish to operate three of them on a six-volt battery you will have to place them in series.Fig. 287.—How Lamps are Connected in Multiple.Fig. 287.—How Lamps are Connected in Multiple.Fig. 288.—How Lamps are Connected in Series.Fig. 288.—How Lamps are Connected in Series.It is sometimes desirable to arrange a lamp and two switches so that it can be turned off or on from either switch independently of the other. This is called "three-way wiring," and is a very convenient method of arranging a light in a hallway. If one switch is placed at the top of a stairway and the other switch at the bottom, a person can pass upstairs or downstairs, light the lamp ahead, and turn it out as he passes the last switch, no matter in which direction the previous user of the light may have gone.The switches are two-point switches, and the circuit should be arranged as in Figure 289.The switch-levers should always rest on one of the contacts and never be left between, as shown in the drawing.Fig. 289.—Three-way Wiring Diagram. The Light may be turned off or on from either Switch.Fig. 289.—Three-way Wiring Diagram. The Light may be turned off or on from either Switch.They are represented that way in the illustration in order not to conceal the contacts.Small brackets made of brass and similar to that shown in Figure 290 are for sale at many electrical supply houses, and will add a very realistic appearance to a miniature lighting plant.Fig. 290.—A Lamp Bracket for Miniature Lighting.Fig. 290.—A Lamp Bracket for Miniature Lighting.Brackets may be constructed after the plan shown in Figure 291. A wooden socket or a pin-socket is mounted on the end of a small piece of brass tubing which has been bent into the shape shown in the illustration. The other end of the tube is set into a wooden block so that the bracket may be mounted on the wall. The wires from the socket lead through the brass tube and through the back or top of the block.Fig. 291.—A Home-made Bracket.Fig. 291.—A Home-made Bracket.Hanging lights may be arranged by fitting a wooden socket and a lamp with a reflector as shown in Figure 296. The reflector consists of a circular piece of tin or sheet-aluminum having a hole in the center large enough to pass the base of a miniature lamp. The circle is then cut along a straight line from the circumference to the center. If the edges are pulled together and lapped the circular sheet of metal will take on a concave shape and form a shade or reflector which will throw the light downwards. The overlapping edges of the reflector should be soldered or riveted together. The reflector is slipped over the base of the lamp, a small rubber or felt washer having been placed over the base next to the glass bulb so that the reflector will not break the lamp. The lamp is then screwed into a socket and allowed to hang downwards from a flexible conductor.Fig. 292.—A Hanging Lamp.Fig. 292.—A Hanging Lamp.A very pretty effect can be secured by drilling the edges of a reflector full of small holes about three-sixteenths of an inch apart and then hanging short strings of beads from the holes. The beads should form a hanging fringe around the edge of the reflector, and if they are of glass, a pleasing brilliancy is produced. Figure 293 shows how to make the reflector.Fig. 293.—How the Reflector is made.Fig. 293.—How the Reflector is made.The batteries for a miniature lighting plant may be located in a closet, under a stairway, or in some other out-of-the-way place. Wires from there may be extended to various parts of the house, such as hallways, closets, the cellar stairs, over a shaving-mirror in the bath-room or in any dark corner where a light is often temporarily needed. The wires can be run behind picture-mouldings or along the surbase and be almost entirely concealed.Fig. 294.—A Three-Cell Dry Battery for use in Hand-Lanterns, etc.Fig. 294.—A Three-Cell Dry Battery for use in Hand-Lanterns, etc.Small Batteriesconsisting of three small dry cells enclosed in cardboard box, as shown in Figure 294, are on the market, and may be bought at prices ranging from thirty to forty cents, depending upon the size and the maker. One of the most convenient and practical sizes of this type of battery has the dimensions shown in the illustration, and with its aid it is possible to construct a number of very useful electrical novelties and household articles in the shape of portable electric lamps, etc. These batteries are quite small and are only intended to operate very small lamps. Only one lamp should be used on each battery at a time, and it should not be allowed to burn long. Some of these batteries will give ten to fourteen hours of intermittent service but if allowed to burn continuously would only light the lamp for about five hours at the most. It is much the better plan to use them only for a few minutes at a time, and then turn the light off and allow the battery to recuperate.An Electric Hand-Lanternis a very convenient device which is quite simple to make. It consists of a wooden box large enough to receive a three-cell battery, such as that shown in Figure 295. The back of the box should open and close on hinges and be fastened with a hook so that the battery may be easily removed for renewal.Fig. 295.—An Electric Hand-Lantern.Fig. 295.—An Electric Hand-Lantern.A three-and-one-half-volt tungsten lamp is mounted on the front of the lantern and connected with the battery and a switch so that the light can be turned on and off at will. The switch may be placed at the top of the box so that the fingers of the same hand used to carry the lantern may be used to turn the light on and off. The lantern is fitted with a leather strap at the top, to be convenient for carrying.The Ruby Lanternshown in Figure 296 is somewhat similar in arrangement to the lantern just described, which may be used both as a hand-lantern and a ruby light for developing photographs.Fig. 296.—An Electric Ruby Lantern.Fig. 296.—An Electric Ruby Lantern.It consists of a wooden box to hold a three-cell dry battery, and is provided with a handle so that it may be easily carried. A switch by which to turn the lamp on and off is mounted on the side of the box.The light is furnished by a three-and-one-half-volt tungsten lamp mounted on the front of an inclined wooden board arranged as shown in the illustration so as to throw the light downward. The sides and bottom of the box are grooved near the front edges so that a piece of ruby glass may be inserted. Ruby glass for this purpose may be purchased at almost any store dealing in photographers’ supplies.The top is provided with a shield which is fastened in position by means of four small hooks after the glass is in place. The shield is used in order to prevent any white light from escaping through the crack between the glass and the top of the box. A ruby lamp of this sort must be made absolutely "light-tight" so that the only light emitted is that which passes through the ruby glass. If any white light escapes it is liable to fog and spoil any pictures in process of development.Fig. 297.—The Electric Ruby Lamp with Glass and Shield Removed.Fig. 297.—The Electric Ruby Lamp with Glass and Shield Removed.By removing the ruby glass and the shield, as shown in Figure 297, the light is changed into a hand-lantern. The back of the box should be made removable so that the battery can be replaced when worn out.A Night-Lightarranged to shine on the face of the clock so that the time may be easily told during the night without inconvenience is shown in Figure 298.Fig. 298.—An Electric Night-Light for telling the Time during the Night.Fig. 298.—An Electric Night-Light for telling the Time during the Night.It consists of a flat wooden box containing a three-cell dry battery and having a small three-and-one-half-volt tungsten lamp mounted on the top in the front with room for a clock to stand behind. The battery and the lamp are connected to a switch so that the light may be turned on and off. By attaching a long flexible wire and a push-button of the "pear-push" type it is possible to place the light on a table and run the wire with the push-button attached over to the bed so that one may see the time during the night without getting up. The bottom of the box should be made removable so that a new battery may be inserted when the old one is worn out.The Watch-Lightis in many ways similar to the clock light just described—but is smaller. It consists of a box just large enough to receive a three-cell flashlight battery. A piece of brass rod is bent into the form of a hook or crane from which to suspend the watch.Fig. 299.—A Watch-Light.Fig. 299.—A Watch-Light.The light is supplied by a three-and-one-half-volt tungsten flashlight bulb mounted on the top of the box in front of the watch. If desirable, the light may be fitted with a small shade or reflector so that it shines only on the dial and not in the eyes. The figures on the face of the timepiece can then be seen much more plainly.The lamp is mounted in a small wooden socket or a pin-socket passing through a hole in the top of the box, so that the wires are concealed. A small push-button is located in one of the forward corners of the box, so that when it is pressed the lamp will light. Two small binding-posts mounted at the lower right-hand corner of the box are connected directly across the terminals of the switch, so that a flexible wire and a push-button can be connected, and the light operated from a distance.An Electric Scarf-Pincan be made by almost any boy who is skillful with a pocket-knife. The material from which the pin is made may be a piece of bone, ivory, or meerschaum. It is carved into shape with the sharp point of a penknife and may be made to represent a skull, dog’s head, an owl, or some other simple figure. The inside is hollowed out to receive a "pea" lamp. Pea lamps with a cord and a plug attached as shown in Figure 300 may be purchased from almost any electrical supply house. The lamp is a miniature carbon bulb about one-eighth of an inch in diameter. The eyes, nose, and mouth of the figure are pierced with small holes, so that when the lamp is lighted the light will show through the holes. The figure should be carved down thin enough to be translucent and light up nicely.Fig. 300.—A "Pea" Lamp attached to a Flexible Wire and a Plug.Fig. 300.—A "Pea" Lamp attached to a Flexible Wire and a Plug.A large pin is cemented or otherwise fastened to the back of the figure so that it can be placed on the necktie or the lapel of the coat. The lamp is removed from the socket of an electric flashlight and the plug attached to the pea lamp screwed into its place. The pea lamp is inserted inside the figure and bound in place with some silk thread. Then when the button is pressed on the flashlight case, the pin will light up and tiny beams of light will shoot out from the eyes, nose, and mouth of the figure.Fig. 301.—Four Steps in Carving a Skull Scarf-Pin. 1. The Bone. 2. Hole drilled in Base. 3. Roughed out. 4. Finished.Fig. 301.—Four Steps in Carving a Skull Scarf-Pin. 1. The Bone. 2. Hole drilled in Base. 3. Roughed out. 4. Finished.The drawings in Figure 301 show how to carve a skull scarf-pin. It is made from a cylindrical piece of bone about five-eighths of an inch long and three-eighths of an inch in diameter. The first operation is to drill a hole three-eighths of an inch deep into the bottom. The hole should be large enough in diameter to pass the pea lamp.Fig. 302.—The Completed Pin ready to be connected to a Battery by removing the Lamp from a Flashlight and screwing the Plug into its Place.Fig. 302.—The Completed Pin ready to be connected to a Battery by removing the Lamp from a Flashlight and screwing the Plug into its Place.Then carve the eyes and nose and teeth. The drawings will give a good idea of the steps in this part of the work. Next round off the top of the skull. Bore a small hole in the back to receive the pin. Put the light inside of the skull, and after it is bound in position the scarf-pin is finished.MISCELLANEOUS ELECTRICAL APPARATUS

Miniature lighting is a field of many interesting possibilities for the young experimenter. Any labor expended along this line will result in something far more useful from a practical standpoint than almost any of the other things described in this book.

Miniature lights, operated from batteries, may be used in various ways; to light dark corners, hallways, or other places where a light is often temporarily wanted without the accompanying danger and nuisance of matches or kerosene lamps.

Miniature lighting has only been made practical by the tungsten filament lamp. The filament, or wire inside the globe, which becomes hot and emits the light when the current is turned on, is made oftungstenin a tungsten lamp. In the earlier lamps, it was made of carbon. The carbon lamp is now seldom used and is highly inefficient when compared to the tungsten.

A Carbon Lampconsumes about three and one-half watts of current for each candle-power of light, whereas a small tungsten lamp uses only about one watt per candle-power small tungsten lamp uses only about one watt per candle-power. The tungsten lamp is therefore three times as efficient as a carbon lamp, and when used on a battery of equal voltage it is possible to obtain the same amount of light with one-third of the current that would be required by a carbon lamp.

Fig. 281.—Miniature Carbon Battery Lamp.Fig. 281.—Miniature Carbon Battery Lamp.

Fig. 281.—Miniature Carbon Battery Lamp.

Carbon lamps similar to that shown in Figure 281 are made in a number of different voltages. The lowest voltage that it is practically possible to make a carbon lamp for is three and one-half. A three-and-one-half volt carbon lamp is designed to be operated on small dry cells such as flashlight batteries. The E. M. F. of a dry cell is about one and one-half volts, but when three small dry cells of the flashlight type are connected in series and used to operate a lamp, their voltage "drops," and the available E. M. F. is only about three and one-half volts.

Four-volt carbon lamps are intended to be operated on large dry batteries or wet cells because they do not lose their voltage as quickly as small dry cells. The table below gives the voltage and candle-power of the various small carbon lamps which are carried in stock by most electrical dealers or supply houses:

MINIATURE CARBON BATTERY LAMPS

3.5 volts for flashlight batteries

4 volts. 2 candle-power

5.5 volts for flashlight batteries

6 volts. 2 candle-power

6 volts. 4 candle-power

8 volts. 4 candle-power

10 volts. 6 candle-power

Tungsten Lampsare made for voltages as low as one and one-half, and will light on one cell of dry battery. The range of voltages is quite wide and varied. A few of the most common sizes are given below:

MINIATURE TUNGSTEN BATTERY LAMPS

1.5 volts. for one dry cell

2.5 volts. for two-cell flashlight battery

2.8 volts. for two-cell flashlight battery

3.5 volts. for three-cell flashlight battery

3.8 volts. for three-cell flashlight battery

4 volts. 4 candle-power

6 volts. 2 candle-power

6 volts. 4 candle-power

6 volts. 6 candle-power

6 volts. 8-10-12-16-20-24 candle-power

Fig. 282.—Miniature Tungsten Battery Lamp.Fig. 282.—Miniature Tungsten Battery Lamp.

Fig. 282.—Miniature Tungsten Battery Lamp.

To find the approximate amount of current drawn from a battery by a tungsten lamp, divide the candle-power by the voltage and the result will be the current in amperes. For example, a 6 v. 2 c. p. lamp will require, 2 divided by 6, or one-third of an ampere.

Six-volt tungsten lamp giving a light greater than six candle-power are only used on storage batteries and are employed principally for automobile lighting.

The filament of a tungsten lamp is much longer than that of a carbon lamp and is usually in the form of a spiral or helix, as shown in Figure 282.

The bases of battery lamps, the base being the lower portion of the lamp, which is made of brass and fits into a socket or receptacle, are made in three different styles:miniature,candelabra, andEdiswan.

Fig. 283.—Lamps fitted respectively with Miniature, Candelabra, and Ediswan Bases.Fig. 283.—Lamps fitted respectively with Miniature, Candelabra, and Ediswan Bases.

Fig. 283.—Lamps fitted respectively with Miniature, Candelabra, and Ediswan Bases.

The miniature and candelabra bases have a threaded brass shell on the outside and a small brass contact-button on the bottom. They are similar except in respect to size. The miniature base is smaller than the candelabra. The Ediswan base is a plain brass shell having two pins on the side and two contacts on the bottom. This type of base is only used in this country on automobiles. The miniature and the candelabra bases are standard for battery lighting. The miniature base has many advantages over the candelabra for the young experimenter, and should be adopted in making any of the apparatus described in this chapter. These three bases are shown in Figure 283.

Fig. 284.—Miniature Flat-Base Porcelain Receptacle.Fig. 284.—Miniature Flat-Base Porcelain Receptacle.

Fig. 284.—Miniature Flat-Base Porcelain Receptacle.

In order to form a good electrical connection between the lamp and the power wires some sort of a receptacle or socket is necessary. The most common arrangement for this purpose is the miniature flat-base porcelain receptacle shown in Figure 284. This type of receptacle is used in places where it can be permanently fastened in position with two small screws.

Fig. 285.—Weather-proof and Pin-Sockets.Fig. 285.—Weather-proof and Pin-Sockets.

Fig. 285.—Weather-proof and Pin-Sockets.

The devices shown in Figure 285 are known respectively as a porcelain weather-proof socket and a pin-socket. Sockets similar to the weather-proof socket are also made of wood. The weather-proof sockets are used in places where the light is to be exposed out-of-doors, as for instance on a porch. The small metal parts are sealed in the porcelain and entirely protected.

The pin-sockets and the wooden sockets are used principally on Christmas trees or in decorative outfits where lamps are hung in festoons. The flat-base receptacle, the pin-socket, and also the wooden socket will be found very useful in making the apparatus described farther on in this chapter.

The Wiresused to carry the current in a miniature lighting system may be of the sort known asannunciatororofficewire if the wires are to be run entirely indoors. The wire should not be smaller than No. 16 B. & S. gauge. When the wires are run outdoors, on a porch, or in some other place exposed to the weather, the wire used should be rubber-covered. Hanging lights or lights intended to be adjustable should be connected with "flexible conductor." This is made of a number of very fine wires braided together and insulated with silk. The wires used in a lighting system should not in any case be longer than it is necessary to have them. When a battery is connected to a system of wires it is found that the voltage at the end of the wires is much lower than at a point near the battery. This is called voltage "drop," and is much greater as the wires grow longer. A light placed at the end of two very long wires will not burn as brightly as it would if connected to the same battery by means of short wires.

Switchescan be made by following the suggestions given in Chapter VII. Suitable switches can be purchased for a few cents at a most any electrical house and will prove very much neater and efficient. They should preferably be of any of the types shown in Figure 286.

The Batteriesused for miniature lighting may be made up of storage cells, dry cells or carbon cylinder cells. Storage cells will prove the most satisfactory, provided that the experimenter has some convenient means of recharging them or of having them recharged. Storage cells will be found of especial value wherever it is desirable to operate several lights from one battery.

Carbon cylinder cells are only suitable where one cell is to be operated at a time. If more than one is used, the battery is liable to become polarized and the lamps will not burn brightly. Carbon cylinder batteries are very inexpensive to renew, and will be found the cheapest method of lighting a small tungsten lamp.

Fig. 286.—Types of Battery Switches suitable for Miniature Lighting.Fig. 286.—Types of Battery Switches suitable for Miniature Lighting.

Fig. 286.—Types of Battery Switches suitable for Miniature Lighting.

If lamps requiring more than two amperes are to be operated on dry cells, the latter should be connected in series-multiple, as shown in Figure 69. Two sets of dry cells connected in series-multiple will give more than twice the service of a single set.

Lamps may be connected either in multiple or in series, provided that the proper voltages of both battery and lamps are used.

When they are to be connected in multiple, the voltage of the lamps should be the same as that of the battery. When they are to be used in series, the voltage of the lamps multiplied by the number used should equal the voltage of the battery. For example, suppose that you wish to use a number of six-volt lamps on a six-volt storage battery. In that case they must be connected in multiple. But if it should be that the lamps are only two-volt lamps and you wish to operate three of them on a six-volt battery you will have to place them in series.

Fig. 287.—How Lamps are Connected in Multiple.Fig. 287.—How Lamps are Connected in Multiple.

Fig. 287.—How Lamps are Connected in Multiple.

Fig. 288.—How Lamps are Connected in Series.Fig. 288.—How Lamps are Connected in Series.

Fig. 288.—How Lamps are Connected in Series.

It is sometimes desirable to arrange a lamp and two switches so that it can be turned off or on from either switch independently of the other. This is called "three-way wiring," and is a very convenient method of arranging a light in a hallway. If one switch is placed at the top of a stairway and the other switch at the bottom, a person can pass upstairs or downstairs, light the lamp ahead, and turn it out as he passes the last switch, no matter in which direction the previous user of the light may have gone.

The switches are two-point switches, and the circuit should be arranged as in Figure 289.

The switch-levers should always rest on one of the contacts and never be left between, as shown in the drawing.

Fig. 289.—Three-way Wiring Diagram. The Light may be turned off or on from either Switch.Fig. 289.—Three-way Wiring Diagram. The Light may be turned off or on from either Switch.

Fig. 289.—Three-way Wiring Diagram. The Light may be turned off or on from either Switch.

They are represented that way in the illustration in order not to conceal the contacts.

Small brackets made of brass and similar to that shown in Figure 290 are for sale at many electrical supply houses, and will add a very realistic appearance to a miniature lighting plant.

Fig. 290.—A Lamp Bracket for Miniature Lighting.Fig. 290.—A Lamp Bracket for Miniature Lighting.

Fig. 290.—A Lamp Bracket for Miniature Lighting.

Brackets may be constructed after the plan shown in Figure 291. A wooden socket or a pin-socket is mounted on the end of a small piece of brass tubing which has been bent into the shape shown in the illustration. The other end of the tube is set into a wooden block so that the bracket may be mounted on the wall. The wires from the socket lead through the brass tube and through the back or top of the block.

Fig. 291.—A Home-made Bracket.Fig. 291.—A Home-made Bracket.

Fig. 291.—A Home-made Bracket.

Hanging lights may be arranged by fitting a wooden socket and a lamp with a reflector as shown in Figure 296. The reflector consists of a circular piece of tin or sheet-aluminum having a hole in the center large enough to pass the base of a miniature lamp. The circle is then cut along a straight line from the circumference to the center. If the edges are pulled together and lapped the circular sheet of metal will take on a concave shape and form a shade or reflector which will throw the light downwards. The overlapping edges of the reflector should be soldered or riveted together. The reflector is slipped over the base of the lamp, a small rubber or felt washer having been placed over the base next to the glass bulb so that the reflector will not break the lamp. The lamp is then screwed into a socket and allowed to hang downwards from a flexible conductor.

Fig. 292.—A Hanging Lamp.Fig. 292.—A Hanging Lamp.

Fig. 292.—A Hanging Lamp.

A very pretty effect can be secured by drilling the edges of a reflector full of small holes about three-sixteenths of an inch apart and then hanging short strings of beads from the holes. The beads should form a hanging fringe around the edge of the reflector, and if they are of glass, a pleasing brilliancy is produced. Figure 293 shows how to make the reflector.

Fig. 293.—How the Reflector is made.Fig. 293.—How the Reflector is made.

Fig. 293.—How the Reflector is made.

The batteries for a miniature lighting plant may be located in a closet, under a stairway, or in some other out-of-the-way place. Wires from there may be extended to various parts of the house, such as hallways, closets, the cellar stairs, over a shaving-mirror in the bath-room or in any dark corner where a light is often temporarily needed. The wires can be run behind picture-mouldings or along the surbase and be almost entirely concealed.

Fig. 294.—A Three-Cell Dry Battery for use in Hand-Lanterns, etc.Fig. 294.—A Three-Cell Dry Battery for use in Hand-Lanterns, etc.

Fig. 294.—A Three-Cell Dry Battery for use in Hand-Lanterns, etc.

Small Batteriesconsisting of three small dry cells enclosed in cardboard box, as shown in Figure 294, are on the market, and may be bought at prices ranging from thirty to forty cents, depending upon the size and the maker. One of the most convenient and practical sizes of this type of battery has the dimensions shown in the illustration, and with its aid it is possible to construct a number of very useful electrical novelties and household articles in the shape of portable electric lamps, etc. These batteries are quite small and are only intended to operate very small lamps. Only one lamp should be used on each battery at a time, and it should not be allowed to burn long. Some of these batteries will give ten to fourteen hours of intermittent service but if allowed to burn continuously would only light the lamp for about five hours at the most. It is much the better plan to use them only for a few minutes at a time, and then turn the light off and allow the battery to recuperate.

An Electric Hand-Lanternis a very convenient device which is quite simple to make. It consists of a wooden box large enough to receive a three-cell battery, such as that shown in Figure 295. The back of the box should open and close on hinges and be fastened with a hook so that the battery may be easily removed for renewal.

Fig. 295.—An Electric Hand-Lantern.Fig. 295.—An Electric Hand-Lantern.

Fig. 295.—An Electric Hand-Lantern.

A three-and-one-half-volt tungsten lamp is mounted on the front of the lantern and connected with the battery and a switch so that the light can be turned on and off at will. The switch may be placed at the top of the box so that the fingers of the same hand used to carry the lantern may be used to turn the light on and off. The lantern is fitted with a leather strap at the top, to be convenient for carrying.

The Ruby Lanternshown in Figure 296 is somewhat similar in arrangement to the lantern just described, which may be used both as a hand-lantern and a ruby light for developing photographs.

Fig. 296.—An Electric Ruby Lantern.Fig. 296.—An Electric Ruby Lantern.

Fig. 296.—An Electric Ruby Lantern.

It consists of a wooden box to hold a three-cell dry battery, and is provided with a handle so that it may be easily carried. A switch by which to turn the lamp on and off is mounted on the side of the box.

The light is furnished by a three-and-one-half-volt tungsten lamp mounted on the front of an inclined wooden board arranged as shown in the illustration so as to throw the light downward. The sides and bottom of the box are grooved near the front edges so that a piece of ruby glass may be inserted. Ruby glass for this purpose may be purchased at almost any store dealing in photographers’ supplies.

The top is provided with a shield which is fastened in position by means of four small hooks after the glass is in place. The shield is used in order to prevent any white light from escaping through the crack between the glass and the top of the box. A ruby lamp of this sort must be made absolutely "light-tight" so that the only light emitted is that which passes through the ruby glass. If any white light escapes it is liable to fog and spoil any pictures in process of development.

Fig. 297.—The Electric Ruby Lamp with Glass and Shield Removed.Fig. 297.—The Electric Ruby Lamp with Glass and Shield Removed.

Fig. 297.—The Electric Ruby Lamp with Glass and Shield Removed.

By removing the ruby glass and the shield, as shown in Figure 297, the light is changed into a hand-lantern. The back of the box should be made removable so that the battery can be replaced when worn out.

A Night-Lightarranged to shine on the face of the clock so that the time may be easily told during the night without inconvenience is shown in Figure 298.

Fig. 298.—An Electric Night-Light for telling the Time during the Night.Fig. 298.—An Electric Night-Light for telling the Time during the Night.

Fig. 298.—An Electric Night-Light for telling the Time during the Night.

It consists of a flat wooden box containing a three-cell dry battery and having a small three-and-one-half-volt tungsten lamp mounted on the top in the front with room for a clock to stand behind. The battery and the lamp are connected to a switch so that the light may be turned on and off. By attaching a long flexible wire and a push-button of the "pear-push" type it is possible to place the light on a table and run the wire with the push-button attached over to the bed so that one may see the time during the night without getting up. The bottom of the box should be made removable so that a new battery may be inserted when the old one is worn out.

The Watch-Lightis in many ways similar to the clock light just described—but is smaller. It consists of a box just large enough to receive a three-cell flashlight battery. A piece of brass rod is bent into the form of a hook or crane from which to suspend the watch.

Fig. 299.—A Watch-Light.Fig. 299.—A Watch-Light.

Fig. 299.—A Watch-Light.

The light is supplied by a three-and-one-half-volt tungsten flashlight bulb mounted on the top of the box in front of the watch. If desirable, the light may be fitted with a small shade or reflector so that it shines only on the dial and not in the eyes. The figures on the face of the timepiece can then be seen much more plainly.

The lamp is mounted in a small wooden socket or a pin-socket passing through a hole in the top of the box, so that the wires are concealed. A small push-button is located in one of the forward corners of the box, so that when it is pressed the lamp will light. Two small binding-posts mounted at the lower right-hand corner of the box are connected directly across the terminals of the switch, so that a flexible wire and a push-button can be connected, and the light operated from a distance.

An Electric Scarf-Pincan be made by almost any boy who is skillful with a pocket-knife. The material from which the pin is made may be a piece of bone, ivory, or meerschaum. It is carved into shape with the sharp point of a penknife and may be made to represent a skull, dog’s head, an owl, or some other simple figure. The inside is hollowed out to receive a "pea" lamp. Pea lamps with a cord and a plug attached as shown in Figure 300 may be purchased from almost any electrical supply house. The lamp is a miniature carbon bulb about one-eighth of an inch in diameter. The eyes, nose, and mouth of the figure are pierced with small holes, so that when the lamp is lighted the light will show through the holes. The figure should be carved down thin enough to be translucent and light up nicely.

Fig. 300.—A "Pea" Lamp attached to a Flexible Wire and a Plug.Fig. 300.—A "Pea" Lamp attached to a Flexible Wire and a Plug.

Fig. 300.—A "Pea" Lamp attached to a Flexible Wire and a Plug.

A large pin is cemented or otherwise fastened to the back of the figure so that it can be placed on the necktie or the lapel of the coat. The lamp is removed from the socket of an electric flashlight and the plug attached to the pea lamp screwed into its place. The pea lamp is inserted inside the figure and bound in place with some silk thread. Then when the button is pressed on the flashlight case, the pin will light up and tiny beams of light will shoot out from the eyes, nose, and mouth of the figure.

Fig. 301.—Four Steps in Carving a Skull Scarf-Pin. 1. The Bone. 2. Hole drilled in Base. 3. Roughed out. 4. Finished.Fig. 301.—Four Steps in Carving a Skull Scarf-Pin. 1. The Bone. 2. Hole drilled in Base. 3. Roughed out. 4. Finished.

Fig. 301.—Four Steps in Carving a Skull Scarf-Pin. 1. The Bone. 2. Hole drilled in Base. 3. Roughed out. 4. Finished.

The drawings in Figure 301 show how to carve a skull scarf-pin. It is made from a cylindrical piece of bone about five-eighths of an inch long and three-eighths of an inch in diameter. The first operation is to drill a hole three-eighths of an inch deep into the bottom. The hole should be large enough in diameter to pass the pea lamp.

Fig. 302.—The Completed Pin ready to be connected to a Battery by removing the Lamp from a Flashlight and screwing the Plug into its Place.Fig. 302.—The Completed Pin ready to be connected to a Battery by removing the Lamp from a Flashlight and screwing the Plug into its Place.

Fig. 302.—The Completed Pin ready to be connected to a Battery by removing the Lamp from a Flashlight and screwing the Plug into its Place.

Then carve the eyes and nose and teeth. The drawings will give a good idea of the steps in this part of the work. Next round off the top of the skull. Bore a small hole in the back to receive the pin. Put the light inside of the skull, and after it is bound in position the scarf-pin is finished.

MISCELLANEOUS ELECTRICAL APPARATUS

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