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Page:Popular Science Monthly Volume 90.djvu/13

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Lawn Sprinkler'Made of a Length of Pipe 923

Dropper Bottle for Bromides 926

A Coating Which Gives the Appearance of Stone to

Wood 927

Detecting Leaks in Inner Tubes with Smoke 927

A Small Refrigerator Suitable for the Milk Bottle 927 Combining Different Woods to Make Fancy Indian

Clubs 928

Fine Aluminum Filings a Violent Elzploaive 929

A Screen Door with an Elxit for Flies 929

Uncleanliness the Trouble-Maker for the Vulcanizer 929

How to Patch an Aluminum Crank-Case 930

An Old Bank Barn Converted into a Tractor Shed 930 The Right Knot for Making Slip Noose About a

Bundle 930

A Chicken Brooder That Does Not Require Heat . 932 Distributirig Cards in a Pack and Disclosing Them 933

Making a Bit Point Take Hold in a Knot 933

A Drill of Self-Hardening Steel for Working Marble 934

Finding Leaks Quickly in Air Tanks 934

Making a Bulb Planter from a Foot Pump 934

Sheet Metal Working Simply Elxplained 935

Large Paper Clip Used in Place of a Key Ring. . . . 936 Dividing Line into Odd Spaces with Ordinary Rule 937

Making a VaJve-Grinuer of an Old File 937

Preventing a Tire from Sticking to the Vulcanizer

Mold 937

Rigid Joints for Making Models in Thin Sheet

Metal 937

A Belt Joint for Use in a Damp Place 938

Collecting Gas from Mud in a Stream of Water . . . 938 A Dust Mulch Cultivator to Keep Moisture in Soil 938 A Coin Used to Close Hole of Broken Oil Window 939 Finding the Speed of a Worm-Gear with a Bit .... 939 Making a Small Syringe to Clean Lubricator

Glasses 939

Measuring Through Obstacles by the Triangula-

tion Method 939

Making a Plumb-Bob Level of a Wood Angle 940

Measuring Circumference with Typewriter Spacing 940 Saving Scrao-Gum When Making Tire Repairs . . 940 Twisting a Wire When Pliers Are Not Available. . 940 Covering an Automobile with Torque-Rod Supi>ort

with Leather Boot 946

RADIO COMMUNICATION

Fastening Binding-Posts on the Ends of Heavy

Wire 147

How to Make a Ten-Ampere Key for Wireless ... 147 A Perfected Slider for Tuning Coils in Aerial

Apparatus 147

Making Photo-Electric Cells to Work from a Light 148 Inexpensive Stranded Aerial Wire Made of Small

Copper Wires 1 49

An Easily Made Switch for Grounding Aerial Wires 152

The Efficiency of a Wireless Receiving Station ... 152

A Floor-Push for Operating the Test Buzzer 152

How to Become a Wireless Operator 153

Valdemar Poulsen's Mercury Drop Impulse- Amplifier 1 56

Constructing a Simple Variable Condenser Switch . I 57

An Elasily Learned Emergency Telegraph Code. . . 158 A Quick Method of Removing Enamel from

Magnet- Wire 1 58

What Radio Readers Want to Know 1 59

The Wireless Detective 232

Conveying Music by Wireless — A Modern Miracle 247

A Knob-Control for an Inductively Coupled Tuner 308

How to Make a Portable Aerial for Wireless 308

How to Become a Wireless Operator 309

A Reliable Radiation and Tuning Indicator 314

Measurement Units of Wireless Inductance 315

Hairspring of a Watch as a Detector-Point Support 316

An Airtight Quenched Spark-Gap 316

Spark Sender for Sustained Wireless Waves 317

Strain Insulator Construction for Aerial Lines. . . . 318

Malunga Coil Slider from a Fountain Pen Clip. . . 318

What Radio Readers Want to Know 319

A Concealed Rheostat for Audion CabineU 467

Increasing the Spring Tension on Vibrator Adjust- ments 467

Device for Testing Spark-Plugs Without Removing

Them 468

Heated Wire Is Telephone Transmitter 468

Scale for Inductive Coupler for Making Log-Book 468

New Patent on Interrupter Spark-Gap 471

An Emergency Aerial Using Door-Bell Wires 474

��Page Increasing the Frequency in Radio-Telegraphy. . . 474

How to Become a Wireless Operator 475

An Easily Erected Antenna for Wireless Operators 478

A New Mercury Interrupter for Spark Coila 479

High Frequency Tesla Coil for Ellectrical Experi- menters 480

Testing Wires and Battery Terminal* for Polarity

with Litmus Paper 480

New York Police Use Wireless 531

Succeeding in Radio Work 626

Delicate Recorder for Wireless Telegraph Signals. . 627

A Handy Method for Voltage Testing ; . 628

How to Become a Wireless Operator 629

An Easily Constructed Detector-Stand for Wireless 633 A Mechanical Rectifier as a Wireless Receiver. . . . 634

Making an Enclosed Rotary Spark Gap 635

A Method of Measuring Antenna Capacity .... 638

Making Money by Wireless 710

Signzdiing "by Wireless" Without Instruments. . . 787 Holding the Telephones Tightly Against the Ears 790 A Homemade Floor Push Button for Annunciators 790 Imitating Hard Rubber with Fiber as a Base. . . . 790

Using a Well for Ground Connection 790

Armature Winding for Small Series Motor 791

Calibrating the Receiver for a Wireless Set 792

Making Small Slots in the Frame of Pancake Helices 793 Making a Simple Relay Key for Wireless Operators 794

A Multiple Key for Wireless Messages 794

A Multiple Electrode Rotary Spark-Gap 794

A Novel Crystal Support Made of Flashlight Globe 794

Wireless in the Trenches 795

Improving the Wireless Aeroplane Set 799

Switch Points for Radio Instruments 799

How to Make a Sending Oscillation Transformer. . 800

The Sensitivity of the Telephone Receiver 800

New Wireless Station on African Coast 950

Precise Resistance Measurement by the Volto-

meter- Ammeter Method 951

Increasing the Efficiency of the Poulsen Arc 952

An Elxperimental Wireless Aerial Made of Zither

Strings 953

Making a Tuning Coil Slider writh a Good Contact 953

A Simple Elx{>erimental Spark-Gap in a Case 953

Connections for Vacuum Tubes in Use with Wire- less Telephony 954

Increasing the EAciency of a Receiving Outfit. . . 954

A New Rotary Variable Condenser 955

An Improved Method of Aerial Construction. . . . 960 Some Useful Hints for the Radio Operator 960

RAILWAYS

Going to School in a Freight Car 22

A Fireless Locomotive 45

Putting Railroad Wheels on Automobiles 82

A New Railway Handcar Mowing-Machine 83

Scrubbing Brushes by the Mile for Cleaning Loco- motives 117

Car-Pullers Take the Place of Switch Elngines 195

The Old Soda Fountain on Wheels 263

Delivering Treun Orders to Conductor and Engineer

on Sp>eeding Trains 324

Rescuing a Drowned Locomotive 354

Light Railroading Accomplished by Automobile. . 362

A Land Ride for Whales 384

Meat Packing with the Aid of an EJectric Railway 414 Building a Street Car Line Without.Stopping Work

or Cars 435

Moving a Railway Car by Hand 538

Alaska's "Pupmobile" Railroad 584

Safeguarding Open Drawbridges 599

Railroading in Alaska Is Still Far from Rapid. . . . 664

Clearing the Tracks of a Crippled Car 678

A Portable Electric Welding Apparatus 734

Locomotive Coal Machinery 910

Dispatching Cars on One-Track Linea 918

Shower Baths for Hogs 919

SHIPS AND SHIP BUILDING

The Elnd of One of Farragut's Old Flagahipa 13

The Superdreadnought Pennsylvania 17

Building a Ship Like Caesar's 74

Rich Vagabonds of Florida Rivers 219

The Biggest Battle Cruiser 268

Floating Safes for Ocean Liners 323

A Cargo of Dried Codfish Sunk a Schooner 349

A Round Trip to the North Pole in Ten Day*. . . 434

The Life-Preserver Chair Cushion 486

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