Page 



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 



