A WEE boy, scarcely old enough to have accurate control of his hands, dumped a heavy load of sand from his toy truck. I marveled at the mechanism that enabled him to lift the weight. And yet, the ratchet that tilted the load was but an application of one of the oldest principles of mechanics—that of the lever.
The SERVANT PROBLEM Solved and a Good Investment Made
A Service for Readers
MRS. TULLY seemed unusually well pleased with something as the family sat down to dinner one evening recently. “What’s up?" queried her husband, all filled with unmasculine-like curiosity. “I’ve solved the servant problem," announced Mrs. Tully.
ANYONE with money available for investments will find the booklets listed below of help in getting ahead financially. You may obtain any of these booklets by writing direct to the issuing house. It will be appreciated if you mention POPULAR SCIENCE MONTHLY when writing for booklets.
FEW owners of radio sets attach sufficient importance to the source of vacuum tube plate supply that they use and the rôle that this plays in the radio outfit. If they appreciated how much the proper operation of the receiver, its quality of reproduction and economy of operation depended on this very important radio accessory, they would take considerably more care in its selection.
Shoes from Cornstalks, Paint from Straw and Other By-Products May Save Us Millions
YOU who pay grocery bills and the farmer who grows the groceries may peer hopefully these days into scientific laboratories. There effective methods of accomplishing that seemingly impossible feat—cutting the costs of food while simultaneously increasing the prices of farm products— are being found.
A flaming story of the men who tame rivers of steel— How one of them seared the craven fear from his soul
EDMUND M. LITTELL
CHUCK SELLERS might look like a real steel man; the letter that introduced him might in so many words say that he could do a thing very few men had ever done, but—Pat Donnell, the black-eyed giant who ruled the open hearth furnaces of Argo Steel, looked from the man to the letter with an eye that saw behind the words.
How Automobile Racing Makes Cars Faster, Safer and More Comfortable—Episodes of Famous Races
THEIR engines roaring, their cars never more than a few feet apart, the two lurched around that treacherous dirt track—Barney Oldfield in his famous Blitzen Benz and his bitter rival, Ralph De Palma, in a monster Fiat— cars capable of bettering two miles a minute.
How Our Cities Are Seeking to Purify the Air Breathe by Washing Away Tons of Poisonous Soot
GEORGE LEE DOWD
MODERN cities have made enormous progress in cleaning out their dirty corners and purifying their food and drink; yet, until very recently, they have given hardly a thought to supplying their people with clean air to breathe. To emphasize this point, a noted scientist attending a luncheon in his honor in a great middle western city recently took samples of the air in the room.
The Airman Who Flew to the Pole Tells How He Plans to Hop from New York to Paris
COMMANDER RICHARD E. BYRD
THE minute the World War ended I began laying my plans to hop the Atlantic. In May, 1919, Commander Reed, U.S.N., did the trick via the Azores, covering 2,150 miles in 26 hours 45 minutes, not counting his stopover at Ponta Delgada.
OUT on the water at the Ports-mouth, N. H., Navy Yard, floated the submarine S-48—wrecked on the rocks of Jeffrey Point in January, 1925. On shore, some 500 yards away, stood three puffing bulldog locomotives, hitched in tandem. Between stretched a mile and a quarter of steel cable.
Experiments and Triumphs of One of America’s Pioneers of Speed—Third in a Remarkable Series of Articles
Frank Parker Stockbridge
GLENN CURTISS was the least excited of all those who watched him fly the White Wing, that day in May, 1908. Jubilant over their first real flight without a smash, the members of the Aerial Experiment Association gathered in the “think-orium” to consider “how come.
Petted rodents that live thirty times as fast as men give us new knowledge about our minds and bodies
H. C. DAVIS
THE rat, ancient enemy of mankind, now has been sent to college as the friend of mankind. While the vicious alley rat is hunted and destroyed as a carrier of disease, his favored cousin, the white rat, is being pampered and educated by science in remarkable experiments calculated to make the human race healthier, happier and wiser.
How strange African breed transmits lust for human blood from generation to generation, and causes terror in native villages
CAPT. C. R. S. PITMAN
THE man-killers! A cry of warning spreads terror through the African village. Women and children scurry to safety. Black-skinned warriors hurriedly gather, armed with nets and spears. Quick death, in the form of a band of fierce man-eating lions, has stalked once more upon the community, slaying and devouring two of the inhabitants.
Josef Hofmann, World-Famous Pianist, Has Given Us Auto Springs and Other Inventions
IT WAS a cold, clear day. Every boy in Berlin whose blood was thicker than water tingled with the call of the ice ponds. Skates dangled and glittered in the sunlight as girls and boys, chatting gayly, hurried toward the Spree river or the other ponds and waterways of the German capital.
THE new tests remarkable on this page afford an entertaining and reliable way of measuring your general mechanical ability without the use of workshop equipment. The only tool required is a sharp-pointed pencil. They are so simple that anyone can enjoy them; yet actual practice has proved them to be accurate yardsticks in determining your skill and speed in working with your hands.
Questions about Cellars, Floors, Roofs, Masonry, Lumber, Heating, Construction, and Here Are Some of My Answers
JOHN R. McMAHON
FASCINATING letters from all parts of the United States and Canada, not to mention Japan and points yet more remote, flock into the home building department of this magazine. They commend, criticize, debate, and mostly ask for specific information in regard to the writer's particular problem.
How the “Zero Mark" at Washington Fixes Property Boundaries and Aids Surveyors
CAPT. EDWIN T. POLLOCK,
THERE are many “zero marks.” A scientist working with temperatures bases his calculations on what he calls “absolute zero,” —273.1° centigrade (—459.6° Fahrenheit), a point no one wishes to see or feel; an almost imaginary point where there is an entire absence of heat.
A fascinating novel of science, adventure and ingenuity—From the Stone Age to Civilization
ON A pleasure cruise among the Aleutian Islands, Parker and Thornton, partners in a Seattle engineering firm; Williams, a young naval architect, and Kelly, a deck hand, fell into the clutches of Kiska Joe, murderous half-breed seal poacher.
I Did—Once—and Found That, Though They Made a Fine Test in the Store, in the End They Were an Expensive Luxury
THE check that I made out to pay for our new radio outfit put quite a dent in my bankroll, but the wife and I both agreed it was worth it. The set worked fine, and in fact we found that, while it had cost us a lot of money, it promoted economy in other ways.
How to Check Up on Possible Weak Points in Your Antenna, Tubes, Wiring and Loudspeaker
Five Rules for Good Reception
ALFRED P. LANE
YOUR radio receiving equipment is like a chain. It is no stronger than its weakest link. And there are possible chances for defective links in the path of incoming signals all the way from the end of the antenna to the loudspeaker. At every step the radio signal follows the proper path only when it is forced into it.
WHEN you decide to bring your old set up to date by installing modern audio transformers and a power tube in the last stage of audio amplification, remember that, for best results, you must use either an output transformer or a choke and condenser to keep the heavy plate current from the power tube out of the windings of the loudspeaker.
Invention Prints Sounds and Pictures on Same Film, Uses Standard Movie Projector
ALDEN P. ARMAGNAC
CALLED the “photophone” by its inventor, C. A. Hoxie, a new device to merge motion pictures and sound, developed after several years of experiment at the Schenectady, N. Y., laboratories of the General Electric Company, amazed spectators recently at its first demonstration.
How Lightning and Earthquakes Travel—New Paper Textile Developed—The Perfect Mutton Sheep—Other Advances
Animal Breeding Cuts Living Costs
Amateurs Discover Comets
Fireflies’ Secret Sought
Animal Life Chemically Started
Rich Children Steal, Poor Honest?
Trailing Ancient Man
He Makes Earthquakes to Order
Woman Invents Paper Textile
Mind Reading Tested by Radio
Minnesota Makes Radio Record
THE world’s supplies of vital necessities from the farm, such as meat, milk, wool and grain, depend more and more on remarkable experiments breeding better animals and better crops. Recently, for example, experts of the animal breeding research department Edinburgh University completed experiments which promise farmers the ideal mutton sheep—one which will produce an abundance of finest wool, and also will bear twins with surprising regularity.
IN OUR February issue we offered $100 in cash prizes to readers submitting the best original designs of human figures made from the fourteen pieces of the Stomachion puzzle game of Archimedes. A number of the prize winning entries are reproduced here.
TWO men who dared torture at the hands of savage Mongolians to obtain scientific trophies in strange forbidden lands—William J. Morden, leader of the expedition and James L. Clark, assistant director of the American Museum of Natural History —returned the other day from their perilous search.
Tiny Life Cell, 4/1000th Inch Long, Electrified Amazing Experiment, Becomes More Active Than Ever
WITH a glass tube whose point is smaller than a singlelife cell, a microscope and a supply of electricity, a scientist in the zoÖlogy department of the University of California has just demonstrated that protoplasm, the substance of which all living organisms are made, is an excellent conductor of electricity.
HASTILY organized squads of men in Kern County, Calif., are resorting to warlike methods to check an unprecedented migration of house mice. Ousted by torrential rains from a dry lake basin, millions of the rodents have overwhelmed neighboring towns.
Frenchman Plans Strange Floating Islands to Harness Ocean's Heat
THAT floating factories drawing their power from the ocean depths may some day dot the tropical seas is the amazing prediction of Prof. Georges Claude, French inventor, in suggesting a method of harnessing the vast stores of “thermal energy” of warm seas.
New Picture-Telegram Service between Berlin and Vienna
Builds Rotor Windmill
WHEN a forest log is sawed into planks, there is bound to be some waste; the circular, bark-covered outside will not make trim boards. Instead of throwing it away, however, Swedish mill owners have found a new use for it in the country’s blast furnaces.
California “Picks and Carries” Its Desert Roads after Sandstorms
Your Footprints Betray You
Who Works for a Living?
A Home Gym
This Tire Patch Sticks!
Tests Office Clatter
ORDINARY road building methods would be of little avail in the desert region of California’s Imperial Valley, where paths are obliterated overnight by avalanches of wind-blown sand. The California Highway Commission solves the problem by building portable roads, which may be taken up bodily and removed to new locations alter wind-storms.
Will Mystery Car Break World’s Speed Record on Florida Sands?
The Biggest Hands in Baseball
Temperature Runs Clock
Motor Ship Has “Electric Cow”
Toy Race Track Offers Thrills
WITH this strange dachshund of a car, Major H. O. D. Seagrave, British automobile racer, will soon try to break the world's speed record on the beach at Daytona, Florida. His mystery “eight" is said to develop a thousand horsepower with its two engines.
SO THAT Londoners may practice skiing right at home and be experts by the time their annual holiday in the Britisher’s winter paradise—Switzerland —comes around, a leading London department store has installed a real practice slide in its own building.
MORE grotesque than the bat that inspired its design, this amazing airplane, representing man’s latest attempt to learn new secrets of speed from the flight of birds, recently made its first trial flight in Paris. Even the propellers are of fantastic construction, though the machine is powered by the newest Blériot motors, of the type designed for commercial airplanes.
SO LIGHT that you could put it on your shoulder and go for a hike, the latest racing shell is made of duralumin, the same light metal alloy that goes into the framework of modern aircraft. Built for the Naval Academy at Annapolis, the new one-man boat weighs only twenty-six pounds, or half as much as the cedar shells in which Navy oarsmen have in the past developed their skill for rowing regattas; and the designer, Walter Hoover, expects it to slip through the water with scarcely an effort.
TRAFFIC law offenders in Chicago, after being duly sentenced and fined, are now given the further benefit of class instruction to teach them better observance of the city’s traffic regulations. The class above is learning what the traffic lights mean.
NOW they’re running cars on acetylene in thrifty France. M. Jaquelin, a French engineer, has discovered that this familiar gas; once widely used for auto headlamps, works admirably as a substitute for gasoline—and cuts his gas bill in two, he says.
WITH the new automatic device illustrated, your garage door will swing open as if pushed by unseen hands when the auto wheel runs over a ground plate in the driveway. Two arms on the doors are operated when the plate throws an electric switch controlling the motor of the door mechanism.
WHEN you make a fresh entry in your check book, the old stubs can't spring back and blur the ink if you have one of these handy holders to keep the pages in place. A curved sheet of metal holds back the leaves, while three prongs keep the device from slipping.
DRIVE up to this novel portable garage, raise a handle, and the entire front half will slide up so you can run the car inside! A pull on the chain hanging from the handle closes it again. Made of two steel sections that telescope into each other, as shown in the two pictures, the garage reduces building construction to its simplest terms.
TEA kettles, pails, milk cans and automobile bodies are today “sewn together” at the seams with liquid metal by new welding machinery that remarkably resembles the sewing machine in operation. As in a sewing machine, the metal sheet, with edges overlapped, is fed between two rolls, and an electric current interrupted a thousand times a minute deposits spots of metal that serve as stitches to bind together the lapped metal.
WHILE wreckers recently tore down the apartment building that had housed it, and literally left it without a roof over its head, a New A ork City bank continued to do business as usual. Even after the structure had been completely razed, depositors found the bank still standing in a corner of the excavation, its walls and plate glass front gone but protected from the elements by a light wooden framework and a covering of tar paper.
A RECENTLY constructed masterpiece of model making, made in California, depicts in miniature every phase of the entire oil industry. It covers an area twenty feet long and is divided into four sections—the wells, the refinery, transportation, and uses in daily life.
CARTONS to hold your groceries, cigarettes or electric light bulbs are whisked out of the remarkable machine below at the amazing rate of 1200 a minute, stamped complete with their colored designs. Using a roll of paper instead of flat sheets, according to its Minnesota inventors, eliminates waste at the irregular ends of the carton.
NOW you can burn smaller coal in your furnace, at a tremendous saving, according to Dr. W. A. Noel of the U. S. Department of Agriculture. Government scientists have perfected a device that, placed in the fire box, creates the strong draft needed to burn “buckwheat” coal.
Talking Movie Camera “Photographs” Sound with Pictures
Wants Bright-Colored Buildings
Outdoor Map Covers Garden
“Canned Heat” for Italy’s Railway Trains
IN THE latest talking movie process, known as “movietone,” Fox-Case of New York believe they have achieved the utmost in simplification. Both pictures and sound are photographed by a single camera. Within the camera, a glowing violet lamp of new chemical composition prints on the film margin voices picked up by a microphone.
THOUGH masks are as old as civilization itself, it remained for W. T. Benda, famous illustrator and artist, of New York City, to create an entirely new and distinctly modern type. Many a star of the stage is willing enough to hide her own face behind such a creation as that in the picture, to which the artist is applying a few finishing touches.
CAN motors be designed to drive racing cars faster and faster? Or is there a mechanical speed limit beyond which no motor can go? With twelve cylinders said to be no larger than demi-tasse cups, a strange new motor being tested secretly by a French automobile company in Paris is expected to drive a car at 250 miles an hour.
Try Th ese Fascinating Tests to Measure Your Abilities
The Nine-Celled Square
The Circulating Coin
Mental Scissors Cutting
A Joker in the Scales
I NSPECTION of the design above, a square containing nine cells, reveals that at eight points of intersection the number of branches is odd. The rule for unicursal analysis is to (Ii vide the total number of odd nodes (points of intersection) by two, to de termine the number of continuous lines necessary to construct the figure.
Needless “Stepping on It" Strains Every Working Part of 1 our , Says Gus
What Was Wrong with Captain Horne’s Car?
PERCIVAL STEBBINS jammed' the throttle down to the floor boards and vigorously thumbed the horn button preparatory to making his usual wild dash up Marley Hill. He waved his hand disdainfully to the driver of a spindly little coupe as he flashed by.
How to Solder Tank Floats, Build Clothes Compartment, Plug Leaks
Ten Dollars for an Idea!
Protects Garage Padlock
These Jacks Will Save Tires
Removes Spindle Bushings
Save the Running Board
Cork Will Plug Water Leaks
WHEN you attempt to solder up a leak in a carburetor or vacuum tank float, the heat of the iron causes the air inside the float to expand. The air pressure produced then forces bubbles of air through the hole you are trying to solder, making it very difficult to seal the hole.
How You Can Make a Removable Woodworking Top for Use on Any Kitchen Table
E. E. ERICSON
IVCJv of space for a workshop or even for a workbench is j proving more and more to be a serious difficulty in the average small home. The modern fiat or apartment is planned without any thought of giving the handy man a chance to express himself in mechanical work.
Speedy Toy Motor Cruiser Run by Radio C-Battery—Costs Little
How to Mix Plastic Finishes with Flat Wall Paints
FREDERICK P. BERRIAN
JJST mention motor boats to a boy and see the broad smile that lights his face. That’s true, too, of many men, for there is something exceedingly fascinating about a toy motor boat that will run speedily under its own power. Of all the shop problems I have tried with boys in my manual training classes, nothing has been as popular as the making of motor boats.
Three Ways to Remove Old Varnish—Bleaching Stains with Oxalic Acid—Sandpapering—Applying Wood Filler
RALPH G. WARING
FLOORS are one of the greatest sources of household care. They are scuffed and scraped like no other woodwork and the moment they are neglected, their scratched and dingy appearance becomes an eyesore. To keep them in condition is not particularly difficult, but you must know just what to do and how to apply and preserve the various floor finishes.
THE gate-leg table Is peculiarly well fitted to the modern home. It can be folded so as to take up a minimum of space, and extended cpiickly and with scarcely no effort when a larger table is needed. As the principles involved in its construction are simple and do not call for great manual skill, the making of gate-leg tables should prove of interest to the home cabinetmaker.
He Has Few Tools and No Experience, but Turns Out a Neat and ATellow-Toned Instrument
WHEN i )>raised Bob s new five-tube radio receiver, he was pleased, but lie frowned as he looked at the loudspeaker. It was of the horn type and, judging from the style, must have been on the radio dealer's shelf for two years or more. “ What do you think of that stovepipe?”
After the gunwales have been glued and clamped to the hull, the joint is made doubly secure with J4 in. long bank pins
Fitting the ribs in place
Easily Made Trellises
CAPTAIN E. ARMITAGE MCCANN
READERS who have followed the instructions given last month for making the hull of a Viking ■ship model will have already realized that it is indeed a swift craft we are building. This will be even more evident when we get the gunwales on, which we shall now proceed to do.
A CORNER cabinet to display one's favorite set of dishes is a very useful addition for that ever-popular nook, the breakfast room. The cabinet illustrated is attractive, takes up little room, and also has a convenient drawer for silver. The material is kiln-dried whitewood.
S AY, Bill Harvey,” Simpkins remarked confidentially to Smith, the young machinist, “I hear Tom is going to cjuit the foreman’s job after awhile and go to raising fruit and chickens out on his farm. Did you hear anything about it?” “No. I didn’t,” Harvey replied in surprise.
PLACED conveniently near the flower garden or in a shady spot on the lawn, a garden bench looks decorative and is especially inviting and restful after a tilt with weeds or lawn mower. The writer recently built one that he thinks will be deemed attractive, and submits it herewith to his fellow workshop enthusiasts.
BOXES filled with growing plants and vines are picturesque additions to the home grounds. Many types of stands may be made for this purpose and three especially simple ones are illustrated. Cypress is one of the best woods for plant stand boxes because it is so little subject to decay.
IN OUR December issue there appeared an article showing how to make an automatic block signal system for model railways. The diagram and instructions gave constructional details and wiring directions for a system that would work with the trains running in one way only.
THIS fly is made from a clothespin, two maple seeds and six lengths of electric bell wire. The legs are placed in holes in the body and, like the wings, are fastened with glue or sealing wax. A coat of clear varnish or shellac is applied to stiffen the wings.
Sharpening y Cleaning and Oiling Lawn Mowers— Repairing a Hose—Rakes, Hoes and Spades
ROBERT S. LEWIS
NOW is the time to fix the lawn mower, hose and gardening tools and forestall those sudden breaks which always come at “just the wrong time.” First, the lawn mower. It is sure to need a good oiling. Use a heavy cylinder oil, such as for motors; light oil doesn't stay “put.”
READERS of the preceding articles on the block puzzle, otherwise known as the “Chinese cross,” may be interested to learn that it is possible to tell by simple inspection of six blocks or their drawings whether they will fit perfectly or have an internal cavity.
MANY a fish is lost because the line gets entangled around an oar dragging in the water. Likewise, oars are in the way if they are lifted into the boat. A simple method of overcoming this fault is shown ABOVE.
PAPER can be used for many things besides writing, wrapping and printing. It can be made to act as a preservative and as a means for preventing the tarnishing of silverware. It may be made waterproof, fireproof and fat proof. These are only a few of the many and varied uses of specially treated paper.
Replacing a Common Snap Switch with a Flush Switch
How to Varnish Wall Paper
TO REPLACE a common snap switch with a flush switch is a relatively simple undertaking for the amateur electrician. First open the main house switch. Take off the knob and cover of the snap switch (Fig. 1), disconnect the wires and remove the switch entirely.
DISCARDED pieces of linoleum can he put to many uses in keeping a home shipshape. Kitchen and other tables with worn and cracked tops may he reconditioned by covering them with linoleum. If painted, varnished or shellacked, the linoleum makes a smooth, durable top.
HOLES of varying size can be drilled through iron up to ¼in. in thickness with the inexpensive drilling device illustrated. The machine is an inexpensive polishing head driven by an old vacuum cleaner motor, the many uses of which have been described previously in POPULAR SCIENCE MONTHLY.
Has Convenient Foot Rest and Compartment for Cleaning Materials, Brushes and Cloths
WILLIAM W. KLENKE
"WHAT is the trouble, Frank?" I asked, as lie strolled into the school shop with a downcast face. “I was called down at. drill inspection in the gym for not having my shoes polished," he replied. “Well, that suggests a good idea for your next model—a shoe polishing stand.”
For Use on Emergency JUrecking Car of Small Garage
Gripping Small Polished Rods
GEORGE H. CAPPEL
SOME kind of a wrecking crane is almost a necessity in every commercial garage, large or small. Many establishments are able to purchase one of the rather elaborate cranes on the market, which, when mounted on a wellpainted truck, makes a good moving advertisement of the garage.
IN THE illustration below is shown a two-in-one tool—a set of toolmaker’s buttons that serves also as a set of “mike” checks. The diameter of the buttons is .500 in. and lengths are .750, .625, .500, and .375 in. respectively. They are hardened, ground and lapped all over.
IN THE illustration below is shown a simple yet accurate way of drilling a central hole transversely through round stock. It is equally applicable to plain and threaded work and can be used in any shop. So little time is required for the necessary preparations that it will often pay to use the method even for drilling a single piece.
ELECTRICAL shops or machine shops assembling relatively small parts in quantities, will find the tool illustrated convenient for driving screws. It can be used either in a speed lathe or on a drill press. There is a holder of machine steel with a taper shank to fit the machine upon which the tool is to be used.
IN A Denver steel shop, standard 8 in. channels, which are to be punched for rivets, are balanced in a sling made as shown. Two hooks 10 in. long are used and over these a short section of 2 by ½in. bar, with a hole near each end, is slipped. With a man at one end to steady them, the beams are carried easily by the overhead crane to the motor-driven punch, and held up while the holes are being made.
IN ORDER that long holes might be measured with more certainty, the writer made a handle for his inside caliper as shown in the accompanying illustration. It is of sheet iron and may be readily detached from the caliper. A strip of sheet metal is bent back on itself and offset to go over the joint of the caliper.
ACENTROLINEAD is desirable in drafting rooms where numerous perspective drawings have to be prepared, but it is a rather expensive instrument. To make one, however, is a relatively simple undertaking. The instrument illustrated was made of celluloid such as is used for triangles.
ELECTRIC hand drills, especially when used on heavy work and in difficult positions, have a tendency to jump out of a lone operator's hands if the drill happens to bind in the hole. In one shop a great aid in helping the workman to retain his grip was found in the form of two short sections of old hose slipped over the handles of the motor.
1. Until recent years this curious vegetable was a rarity in America. The fact that it is now so much commoner is due to the development of a great artichoke industry near Half Moon Bay, California. This hay is very foggy, and fog is good for artichokes.
The method of ascertaining the true weight of an article weighed on an off-center scale is to take the square root of the product of the amounts registered on the two sides. In the sketch, these amounts were 8 and 6⅛. The square root of their product, 7, is the true weight of the bottle.