The Ultimate Book of Saturday Science

The Ultimate Book of Saturday Science: The Very Best Backyard Science Experiments You Can Do Yourself

NEIL A. DOWNIE
Copyright Date: 2012
Pages: 488
https://www.jstor.org/stable/j.ctt7s17m
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  • Book Info
    The Ultimate Book of Saturday Science
    Book Description:

    The Ultimate Book of Saturday Scienceis Neil Downie's biggest and most astounding compendium yet of science experiments you can do in your own kitchen or backyard using common household items. It may be the only book that encourages hands-on science learning through the use of high-velocity, air-driven carrots.

    Downie, the undisputed maestro of Saturday science, here reveals important principles in physics, engineering, and chemistry through such marvels as the Helevator--a contraption that's half helicopter, half elevator--and the Rocket Railroad, which pumps propellant up from its own track. The Riddle of the Sands demonstrates why some granular materials form steep cones when poured while others collapse in an avalanche. The Sunbeam Exploder creates a combustible delivery system out of sunlight, while the Red Hot Memory experiment shows you how to store data as heat. Want to learn to tell time using a knife and some butter? There's a whole section devoted to exotic clocks and oscillators that teaches you how.

    The Ultimate Book of Saturday Sciencefeatures more than seventy fun and astonishing experiments that range in difficulty from simple to more challenging. All of them are original, and all are guaranteed to work. Downie provides instructions for each one and explains the underlying science, and also presents experimental variations that readers will want to try.

    eISBN: 978-1-4008-4173-8
    Subjects: General Science, Chemistry, Technology, Physics

Table of Contents

  1. Front Matter
    (pp. i-iv)
  2. Table of Contents
    (pp. v-viii)
  3. PREFACE
    (pp. ix-xii)
    N.A.D.
  4. ACKNOWLEDGMENTS
    (pp. xiii-xiv)
  5. SIMPLE BUT SUBTLE … SIMPLE BUT NOT ALWAYS EASY TO EXPLAIN
    • 1. BLUNDERSPUDS AND CARROT CANNONS—ARTILLERY AND BOYLE’S LAW
      (pp. 3-8)

      The spud gun was a staple weapon of junior soldiers from at least the 1960s onwards. It comprised a tiny piston mounted on the handle of a toy handgun, the trigger of which pulled back a cylinder over the piston. The cylinder had a nozzle that could be jabbed into a potato, removing a pellet. When you squeezed the pistol hard, you compressed air in the cylinder and the pellet of spud was ejected like a small bullet. Later a three-in-one design came out that could do more. It could not only fire pieces of potato, but also squirt water...

    • 2. MR. BERNOULLI’S POP-UP PISTON—MORE BERNOULLI WEIRDNESS
      (pp. 9-14)

      Daniel Bernoulli is responsible for the theory behind what is sometimes known as the Venturi effect, so-called because it was much researched by the Italian physicist Giovanni Venturi. It is a strange and curiously counterintuitive phenomenon.

      A gas, such as air, rushing along a tube from a larger diameter to a smaller diameter has to increase in speed. Otherwise it would all pile up, which is impossible in a rigid tube. But this obvious increase in speed is accompanied by a much less obvious decrease in pressure, a decrease precisely predicted by Mr. Bernoulli’s math. When you push an oversize...

    • 3. THE RAPID-FIRE VACUUM BAZOOKA—FIRE PROJECTILES OR CLEAN THE FLOOR
      (pp. 15-21)

      The Vacuum Bazooka now seems to be in use around the globe. Lurking in the back rooms of physics and engineering departments in the farthest flung corners of our world, you can find assemblies of pipes, fittings, and assorted parts of vacuum cleaners pulled from their regular duties and redeployed to fire all manner of small projectiles, and aimed at targets of an even more diverse range. Bull’s eyes, bowling pins, metal foil sheets, light gates—just about any target will do. When it comes to rapid-fire capabilities, however, the Vacuum Bazooka could do with some improvement.

      Unlike more conventional...

    • 4. SINGLE-BLADE PROPELLERS—VENETIAN GONDOLAS
      (pp. 22-28)

      Venetian gondolas are propelled by the swirling action of a single oar at the back of the boat. Most boats, however, are pushed along by a propeller, and fitting this form of propulsion onto the vessels presents a problem: you have to have a hole below the water line for the driveshaft to go through. This breach in the hull tends to leak water back into the boat, which is bad per se, and to put icing on the cake, you get the motor full of water too, which isn’t too good for the high-voltage ignition circuit. You can drive...

    • 5. SODA MINT FOUNTAINS—THIRST FOR KNOWLEDGE AND WATER QUENCHED AT ONCE
      (pp. 29-33)

      In Africa, in the volcanic district of Cameroon, there is a crater lake, Lake Nyos, that is continuously saturated with carbon dioxide bubbling up from underwater fissures. Periodically, the lake boils, with a massive release of CO₂ gas suddenly seething at its surface. This is highly dangerous for the inhabitants along the lake’s shore because of the toxic nature of high levels of CO₂. Tragically, releases of gas have several times been large enough to kill hundreds of people.

      The way this seems to happen is as follows: something, perhaps changes in ambient temperature or wind, create a vertical current...

    • 6. THE ARMOR-PLATED SANDCASTLE—GAS AND SAND COMBINE
      (pp. 34-38)

      Sandcastles are famously ephemeral buildings. On the tidal beaches of the Atlantic and Pacific, a sandcastle has only a few hours—at most half a day—before the tide returns to claim it. Which doesn’t mean they aren’t a lot of fun. You can install hydraulic works like tiny rivers to feed the moat or castle duck-pond, or add decorative features made from molded sand or seashells—there are lots of options to explore.

      In addition to the tide problem, however, sandcastles suffer from a rather basic lack of strength in the material department. Adding the right amount of water...

    • 7. THE RIDDLE OF THE SANDS—WEIRD BUT BEAUTIFUL PATTERNS APPEAR, ALL OF THEIR OWN ACCORD
      (pp. 39-46)

      The unruly behavior of granulated materials is familiar to those in industry who have to deal with them. Ask any chemical engineer what he would rather deal with, a liquid or a solid, and he will tell you that solids are tricky and troublesome in comparison to liquids. They don’t flow neatly like liquids, you can’t pump them (except with very special equipment), they can clump together, and on occasion they can block up the most carefully designed industrial plant. However, flowing granules, and especially mixtures of granules, tricky though they are, are also very interesting, as we will now...

    • 8. TRICKS OF SIDEWAYS LIGHT—MAGIC MONDRIANS AND INVISIBLE WATCHES
      (pp. 47-54)

      It is thought that long ago in the Dark Ages, Viking navigators used enigmatic crystals to help them guide their longboats across the northern oceans. The same polarizing calcite crystals, known as Iceland spar, allowed Christiaan Huygens, the Dutch astronomer, to make the first systematic investigation of polarization in the seventeenth century. Polarization derives from the fact that light can vibrate electromagnetically in the two directions at right angles to the axis along which it travels—just as a vertical string can vibrate in both north-south and east-west horizontal directions. The unaided human eye cannot see the polarization of light,...

    • 9. SUNBEAM EXPLODERS—RAY GUNS AREN’T SCI-FI ANY MORE
      (pp. 55-63)

      The first weapon of the invading Martians in the H. G. Wells story sounds like a modern-day infrared carbon-dioxide laser. Which is rather remarkable considering that Wells wrote sixty-two years before the first laser saw the light of day and added its own special form of light. But you don’t need a laser to explode things from a distance. Our method uses only a sunbeam—and it is surprisingly effective.

      The power of the sun always seems weak in England. This is hardly surprising when you look at the latitude of London and even the most southerly parts of England....

    • 10. THE DEAD-OR-ALIVE BALL—TO BOUNCE OR NOT TO BOUNCE, THAT IS THE QUESTION
      (pp. 64-67)

      The bouncing of balls has been studied in physics since Archimedes was a lad. But even comparatively recently there have been surprises. Who would have predicted that bouncing balls—albeit exploding ones—would work as a weapon of war in the hands of aeronautical genius Barnes Wallis? And the extraordinary bounciness of Super Balls made from superelastic polybutadiene still catches people unaware. Don a pair of safety glasses, then drop a large Super Ball on the ground with a small Super Ball on top of it and you might be surprised at just how high and far that little ball...

    • 11. COWBOY COFFEE—YEE HAW!
      (pp. 68-76)

      Coffee bushes grow on hillsides—too many hillsides, some would say. In various parts of the world, but especially in Africa and South America, there are vast tracts of land devoted to coffee cultivation. The small bushy trees—just six feet or so high—yield small unimpressive cherry-like fruits, in the middle of which there are a couple of equally unimpressive beans. In coffee towns like Jardin, high in the hills of the zona cafeterra of Colombia, you will trip over large tarpaulins covered with coffee beans drying in the sun. Once dried, the beans are a dull pastel grey-green....

    • 12. ELECTRIC GLUE—THE MODERN GLUE
      (pp. 77-83)

      Glues of some kind have been used since Stone Age people boiled up fish skins or heated resin from trees to bond sharp flint blades into the wooden shafts of arrows and spears. For millennia, glue continued to be made this way, and then in the nineteenth century the Victorian chemical industry turned its attention to glues derived from rubber. Over the next century, a full understanding of the chemistry of polymers and a deluge of petroleum-derived source chemicals allowed major developments in the field of adhesives. A cornucopia of glues from epoxy to cyanoacrylate came out in the 1950s,...

    • 13. ELECTRIC GUNPOWDER—EXPLOSIVE ELECTRICITY!
      (pp. 84-89)

      In times of peace, explosives are not consumed in any great quantity by the military. This was just as true centuries ago as it is today. Much larger quantities of explosive are actually used in mining and quarrying. In the good old days gunpowder would be charged into holes in the rockface and then ignited by hand, using a variety of ineffective methods to try to protect miners from the blast. At its most crude, a thin trail of powder would be poured along the ground from the shot hole, and the end of the trail ignited while the miners...

    • 14. AN EIFFEL BRICK TOWER—EAT YOUR HEART OUT, MONSIEUR EIFFEL!
      (pp. 90-96)

      Towers of bricks, you may be muttering. That’s not even kids’ stuff. That’slittlekids’ stuff! And it is true that the average two-year-old can construct a tower of three or four wooden blocks laid on top of each other. In fact this skill is actually used to evaluate the development of a young child’s brain and muscular coordination.

      But with some ingenuity, plus a stepladder and a few other odds and ends, you should be able to produce a tower of somewhat more serious dimensions. Up to around 4 m or so (13′4″) should be possible, I reckon. At...

    • 15. DOMINOIDS—FOUR-FOOT BROBDINGNAGIAN MONSTER DOMINOES WILL HIT THE FLOOR AT THE END OF A ROW OF STANDARD DOMINOES
      (pp. 97-103)

      There is something compulsive about setting up rows of dominoes and watching them fall down in a chain reaction when you knock over the one on the end. Grand competitions have been staged, involving stupendous numbers of dominoes, each contestant seeking to grab the world record for the number toppled in one sequence. The graph shows how over thirty years, the number of dominoes toppled has climbed steadily from a fairly silly 11,000 to a completely preposterous 4.5 million!

      In the more recent record-breaking attempts—those featuring 4 million or so dominoes—the pieces usually are not arranged in a...

    • 16. COLLOONS—CIVIL AND AERONAUTICAL ENGINEERING COMBINED: NEITHER COLUMN NOR BALLOON
      (pp. 104-111)

      Impossibly thin columns are capable of supporting improbable loads … if all you’re looking at is compressive strength. In reality, tall, thin columns of material are incapable of supporting even a small fraction of the compressive load that they could take in short lengths. Why? It is all thanks to that curious and often unpredictable behavior we call “buckling.” Buckling is due to the instability of a tall, thin column under a compressive load. A perfect—that is, perfectly straight tall, thin column—could in theory resist the full compressive load that a column of the same material and cross-section...

    • 17. MOTOR BRUSHES—THE SCIENCE OF VIBRATION-DRIVEN VEHICLES IS APPLIED TO A HUMBLE HOUSEHOLD BRUSH
      (pp. 112-116)

      The Motor Brush is an animated brush. In my bookVacuum Bazookas, I named a simpler sort of animated brush a Dougal, after the character Dougal (spelled “Doogal” in the North American version) in theMagic Roundaboutanimation. Seems somebody has been animating brushes for a while now! But exactly how do you go about doing that without the magic of an animation studio? Well, it’s all about good vibrations….

      Two electric motors

      An eccentric wheel

      A propeller

      A battery box

      Batteries

      A switch

      A brush: scrubbing brushes, shoe brushes, and other types can all work well

      Balsa wood (all...

    • 18. A SMOOTH-WHEEL PADDLE STEAMER—INVISIBLE (WELL, ALMOST) MARINE PROPULSION
      (pp. 117-123)

      Paddle steamers had a long and distinguished history, but once the screw propeller had proved itself, they were quickly pushed off the high seas. As we mentioned in connection with Venetian gondolas, the British Navy organised a famous tug-of-war between a paddle steamer, the HMS Alecto, and a screw steamer, the HMS Rattler, boats of similar size. The paddler lost out, pulled backwards by the screw ship, which thus established its superiority for once and all. Ocean-going paddle steamships are long gone, and most steamships with propellers, too. But the Rattler’s propeller is preserved. My photo of it, taken where...

    • 19. A STRING AMPLIFIER—THE POWERFUL SCIENCE OF LOOPS OF STRING
      (pp. 124-129)

      Next time you travel by ship, take a look at the what the guys on the deck are doing as the ship docks. At some point, one of the sailors will throw out a line to the shore, and the line will be used to pull over a heavy mooring rope with a loop at its end. The loop is then slipped over a steel bollard. But then what? The ship is still standing ten feet or more off the quay, and it weighs 10,000 or 50,000 tons, and its propellers are designed to drive it forwards, not sideways. What...

    • 20. THE PUNKAH PENDULUM—AIR-CONDITIONING AND TIMEKEEPING COMBINED
      (pp. 130-135)

      The punkah that we often seen in museums and on film sets is little more than an oversized version of a hand fan, complete with ostrich plumes. In the great country houses in the hotter parts of India, however, a rather more effective device, also called a punkah, was used in by-gone days to furnish a rather effective form of air-conditioning. It consisted of a large and relatively heavy carpet, suspended from the ceiling by ropes along one edge. Pulling on another rope on the bottom edge allowed it to be moved to and fro like a pendulum. The person...

    • 21. THE MAHARAJA’S SUNSHADE—AIR IN MOTION PROVIDES TENT AND AIR-CONDITIONING ROLLED INTO ONE
      (pp. 136-142)

      Here and there in the world there are buildings held up by nothing more substantial than the air inside them. It’s not a bad idea. Forget about solid walls and a roof, all you need to provide shelter from the wind and rain is a thin skin made out of some kind of rubberized canvas and, inside of it, air at a higher pressure than the air outside. A little air pressure will do, just a millibar—a thousandth of an atmosphere—will give you a force of 10 kg on every square meter, plenty to hold up your pneumatic...

  6. SURPRISINGLY SUBTLE … SURPRISES GALORE IN THIS MAVERICK COLLECTION
    • 1. AN ELECTRIC SUNDIAL—TIRED OF RUNNING TO YOUR CAVE ENTRANCE TO GET THE TIME?
      (pp. 145-152)

      If the sun is shining, a stick and a circle of stones is all you need to determine the hour of the day. A sundial of this kind, simple and ancient though it is, contains a number of subtleties, which is why sundials are still designed and built today. Look around, and in most cities and towns you will find a few on prominent buildings and in gardens.

      Some of these sundials are enormous. In several Indian cities—Jaipur in northern India, for example—there are ancient sundials of gigantic proportions. These instruments, often dubbed a “Jantar Mantar,” were used...

    • 2. THE KLEENEX CLOCK—TIME FROM TISSUE PAPER
      (pp. 153-159)

      Hold up a piece of tissue paper and look at it. It seems simple enough. It is not. Put that same piece under a microscope and a complicated jungle assaults the eye: fibers of assorted sizes, some clearly tubular, some solid, all at different angles, twisted and bent around each other. Out of this tangled skein of complexity, however, we can, by applying a surprisingly simple but subtle piece of math, discover quite an effective way of measuring time.

      The Kleenex Clock element is a piece of tissue, four-ply or so, encapsulated by two strips of tape. To form the...

    • 3. THE TORSION TIME PENCIL—PEELING OFF ATOMIC LAYERS AS TIME GOES BY
      (pp. 160-164)

      In this next experiment we are going to demonstrate a timer device based on chemical etching. An early form of miniature delay-action detonator relied on the etching of a thin wire by acid. When the acid finally ate through the wire, this released a spring-loaded detonator plunger, that set off an explosive charge. A number of metals will dissolve readily in an acid solution: zinc in hydrochloric acid, for example. Other metals dissolve readily in alkali solution; e.g., aluminium in sodium hydroxide. However, not all of these combinations work well. Some metals passivate, for example, which means that the etch...

    • 4. THE SWELL-GEL FLOWSTOPPER—STOP WATER GOING UP YOUR GAS LINES
      (pp. 165-169)

      Look into the little packets of material that you purchase to save you the trouble of watering your flowerpots and indoor plants, and you will find small crystal-like pieces of clear plastic a few millimeters across. Tear open an unused disposable diaper, and you will most likely find a similar material. The sole purpose of this material—itsraison d’etre—is to absorb water. These granules swell like crazy when they become wet.

      What other possible uses could we find for this magical gel?

      The Swell-Gel Flowstopper is one possibility. This device was born out of the need to protect...

    • 5. THE VORTEX PUMP—WHIRLING WATER MAGIC
      (pp. 170-174)

      You don’t have to travel far to observe a vortex. If you are drinking a cup of tea or coffee while you are reading this, for example, just take the spoon from the saucer and stir the cup vigorously. You will see the middle of the coffee surface begin to dip downwards further and further as the liquid swirls around faster and faster. Overdo it, of course, and your coffee will end up in the saucer, an effect to which we will later return. And when you stop stirring and take the spoon out, you will notice that the coffee...

    • 6. WAXAULICS—HYDRAULICS FOR CANDLES
      (pp. 175-181)

      Wax is in many ways typical of organic solids, and it is mostly these typical properties that we will put to use in this experiment. The fairly low latent heat of melting of wax will be important here, and also its low heat capacity.

      The purest form of wax, paraffin wax, is comprised of alkane hydrocarbons—molecules consisting of nothing but hydrogen and carbon, with only single-chemical bonds—containing between 20 and 40 carbon atoms. Being a mixture of different molecules, it does not have a precisely defined melting point, but typically it melts between 45° and 70°C (113° to...

    • 7. TELESTRINGS—REMOTE-CONTROLLED ART
      (pp. 182-188)

      With just a single string you can write Morse Code at a remote location. But with two strings, you can do a lot more. With two strings capable of fairly delicate movement, you can actually write letters and words, at least over a modest distance. The two strings provide, in effect, more-or-less Cartesian (x and y) coordinates. As you trace a sketch at the input, you pull the input ends of the two strings to and fro, and the output ends of the strings copy these movements, directing a pen over the output paper.

      A similar system of measuring cord...

    • 8. SQUIRTING STRING—GETTING STRING TO FLOW THROUGH PIPES
      (pp. 189-193)

      We have all sucked liquids through a straw. Curiously, the technique is one that has to be learned—it is not at all like drinking breast-milk. But by age five or so, pretty much all of us will have mastered the art of drinking a milkshake or a soda through a straw. Most of us also will have tried, at some point, eating spaghetti by sucking a strand through pursed lips. The result can be surprisingly effective, although a bit messy if small blobs of tomato sauce are flung off in the process. (Those last few inches tend to whip...

    • 9. SPIDER TECHNOLOGY—THE SILKEN SECRETS OF SPIDERMAN
      (pp. 194-202)

      Spiders don’t always get a good press, but they deserve our admiration for some remarkable technology that is built into their minute, eight-legged bodies. They can make a variety of different kinds of silken thread—strong stuff, thin stuff, sticky stuff, and non-sticky—and they can make it quickly. The orb-web spider takes just an hour or two to weave a spiral-and-spokes web that is more artfully constructed than any fishing net. And that isn’t all. Many species of spiders can fly into the air on a fine thread, at least when they are young and small, while others can...

  7. SIMPLE SECRETS OF THE UNIVERSE … FUNDAMENTALS OF THE PHYSICAL WORLD UNCOVERED IN ELEGANTLY SIMPLE DEMONSTRATIONS
    • 1. THE MOLECULE METER—I SPEAK YOUR MOLECULAR WEIGHT!
      (pp. 205-210)

      In this experiment we will measure molecular weight with the aid of a counting circuit and an item that you may well be wearing on your wrist at this very moment; namely, a quartz crystal. The crystal that is inside almost every wristwatch or clock manufactured today is a piece of pure quartz, a form of silicon dioxide, typically cut into the shape of a tiny tuning fork, just 4 or 5 mm long, with tiny electrodes plated onto it. The crystal is normally enclosed in a small case of copper alloy, often plated with tin or some other bright,...

    • 2. TALKING SPARKS—SEND MESSAGES AT 186 MILLION MILES PER HOUR: SEE HOW RADIO PIONEER MARCONI FIRST SENT RADIO A THOUSAND MILES
      (pp. 211-220)

      With these words Guglielmo Marconi ushered in the age of global communication. From their base in the New World, Marconi and his assistant George Kemp had heard radio signals from the Old World, and they announced their epoch-making achievement with this telegram. Note that they didn’t announce the discovery by radio. Radio was still far too primitive for that. They could only receive radio signals by raising a wire to an immense height with the aid of a balloon, or, if the wind was high, as it often was on the storm-tossed coast of Newfoundland, by kite. They had, at...

    • 3. LIGHT AND LENS PIPES—THE STRONG FOCUSING PRINCIPLE USED IN THE MICROSCOPES OF FUNDAMENTAL PARTICLE PHYSICS
      (pp. 221-229)

      When something is perfectly transparent, you sometimes hear it described as water clear. But it is a curious fact that clear water is not in fact very clear. Anyone who has done any diving in the sea will tell you that the farthest you can expect to see is a distance of a few tens of meters, even in good conditions. Maybe as clear as glass, would be a more accurate expression? But go to a glassworks or window distributor and try looking through a stack of ordinary window glass a meter or two thick. It usually looks green, not...

    • 4. FIRE FROM WATER—THE POWER OF CONCENTRATION
      (pp. 230-238)

      Burning glasses—lens specifically designed to concentrate the sun—have a long history. In “Sunbeam Exploders” (“Simple but Subtle”), we saw that they played an important role of early chemistry, giving access to clean, pure heat power. Burning glasses have been made using a liquid filling: the 10 foot lens developed in prerevolutionary France was glass, but it was hollow and filled with alcohol. Lenses with a liquid surface have not yet been used for any practical purpose, as far as I know, but liquid-surface mirrors have. Large turntables with a shallow trough of mercury have been rotated to form...

    • 5. THE HELIRACKET—WAVES, MOLECULES, AND MUSIC
      (pp. 239-247)

      The Heliracket* is a combination of bagpipes and a bathtap that employs a mixture of helium and air to play a tune. Before we set about constructing ours, we need to outline a few of the basic principles behind the music of wind instruments.

      The cornucopia of musical instruments that have been invented over the years can be categorized in many ways, but one basic grouping is that of wind instruments. These all rely on the production of a musical tone by means of air oscillating to and fro inside a closed vessel of some kind. This can vary from...

    • 6. THE HELITOWER—THE MOMENTUM PRINCIPLE OF ROCKETS AND HELICOPTERS
      (pp. 248-256)

      The need for a lookout has been with us from time immemorial, come peace or war. The ruins of ancient towers on hills and the crow’s nests perched high on the masts of vintage sailing ships are reminders of this basic human need.

      These days wartime requirements for high-level lookout capacity are often supplied by aircraft. Starting with the scout planes of the First World War, successive developments have culminated in today’s drones, bristling with cameras and sensors. Ground-based devices have been evolved as well. The army has, for example, been using mirror- or prism-based periscopes for many years, simple...

  8. CLOXOTICA—EXOTIC CLOCKS AND OSCILLATORS:: A CORNUCOPIA OF UNUSUAL CLOCKS
    • 1. THE PAPERCLIP CLOCK—A MAJOR LEAP FORWARD IN HOROLOGICAL SCIENCE, THE ACME OF SIMPLICITY
      (pp. 259-265)

      There must be at least a thousand more complicated ways to make a clock out of a pendulum, and many of them no doubt provide better technical performance than the the Paperclip Clock we are about to construct. Dava Sobel’s excellent bookLongitudedescribes master clockmaker John Harrison’s heroic creation of the longitude clock, the first timepiece accurate enough to give the longitude position of a ship at sea. Harrison’s 1761 design was the most intricate labyrinth of clockwork ever made, but even ordinary clocks in his day had anchor and lever escapements, barrel and fusee power springs, temperature compensated...

    • 2. THE MICROPENDULUM—THE PRESTIPENDULOUS TICK-TOCK CLOCK
      (pp. 266-273)

      You might wonder why the portable clocks and watches of the past used balance wheel oscillators. What is wrong, you might ask, with simply making a smaller version of the pendulum oscillator used in a grandfather clock? Well, there is nothing basically wrong with making a pendulum smaller, as this project will demonstrate. The balance wheel has, however, an orientation advantage. Most mechanical pendulum clocks—grandfather clocks and even cuckoo clocks—will not operate unless they are within 10 degrees or so of vertical, and they will be inaccurate unless they are rather better levelled than that. But it would...

    • 3. THE STRING THING—BALLET DANCING FOR PENDULUMS
      (pp. 274-279)

      The spiral unfashionable? You could make a case that it is. Outside of its occurrence in shellfish, the spiral is, as a rule, a rare form for an object to take. There are a few engineering devices, to be sure. A type of spiral waterwheel called a “noria” still pumps water to fields in the Middle East. And there are spiral (or scroll) high pressure pumps as well. But these are engineering oddities. The glaring exception to the rule was, until recently, the use of spiral springs on the balance wheel and in the going train of most clocks and...

    • 4. EDDY THE CONICLOCK—A SPINNING DISK POWERS A CONICAL PENDULUM
      (pp. 280-284)

      An eddy current is a current in a plate of metal induced by the motion of a magnetic field across it. Once you have induced such a current, the current produces yet another magnetic field, just like a current flowing around a regular wire circuit in a solenoid electromagnet, for example. Then, what you have, in effect, is two magnetic fields—two magnets—acting on each other and producing a force. This force behaves like a drag force, a force that increases with speed and slows down the movement. Here we use the drag force generated by eddy currents to...

    • 5. THE HUMMING CLOCK—RECYCLE UNWANTED MAINS HUM TO RUN YOUR CLOCK
      (pp. 285-291)

      A while back I had the idea of picking up whistlers—extra/very low frequency (ELF or VLF) waves. Caused by pulsed electrical effects like lightning, these natural VLF radio signals are due to the propagation of waves between the ionosphere and the earth. The ionosphere is the charged, conductive layer above the stratosphere. Pulses of energy propagate at different speeds depending upon their frequency, giving rise to the typical shifting frequency of the whistle sounds. Using earphones on a simple audio amplifier connected to a long wire, you can hear these frequency whistles taking a second or two to rise...

    • 6. AN HOURGLASS WALLAH—THE SANDS OF TIME UPDATED
      (pp. 292-299)

      The hourglass principle is now relegated to history, to providing souvenir makers with employment, and to timing boiled eggs. In the past, however, this simple, inexpensive, and relatively accurate device was widely used. The hourglass is a sealed unit, unaffected by rain or sun. It is also more-or-less insensitive to heat, unlike a water clock in which the viscosity and density of the operating medium varies with temperature. The glass walls of hourglasses, by contrast, have only tiny coefficient of expansion, as have the marble and quartzite sand particles inside them. With such a good basic timekeeper, it seems a...

    • 7. THE KNIFE-THROUGH-BUTTER CLOCK—MELTING TIME
      (pp. 300-306)

      “Like a hot knife through butter,” someone once casually remarked to me, describing the efficiency of a new diamond-sawing machine. “Ahotknife through butter?” I thought. “That isn’t quite right. Surely just ‘a knife through butter’ is the ordinary expression and does the job.” But a thought had been planted, and slowly it began to germinate.

      A few days later, a book landed on my desk all about laser cutting, a process that uses a multi-kilowatt infrared laser (a laser that is roughly a million times more powerful than a laser pointer), along with a blast of high-pressure pure...

    • 8. CREEPY CLOCKS AND TIME PENCILS—THE SLOW FLOW OF SOLIDS
      (pp. 307-315)

      In World War II France, many French people joined Resistance groups, pledged to oppose by all means the Nazi occupation of their native land. The Resistance was often armed by secret air-drop deliveries of special weapons and munitions provided by the British Secret Service or the Special Operations Executive in London.* Among the lightweight guns and packages of explosive were delayed-action detonators for use in sabotage. Ordinary safety fuses (a burning cord) or electric detonator wires were out of the question, since they would be recognized by vigilant enemy patrols at checkpoints. An alarm clock with electric contacts, perhaps the...

    • 9. A POLYMERIZING CLOCK—TELLING TIME WITH GLUE AND CHEMISTRY
      (pp. 316-321)

      Many chemical reactions take place in times just a little longer than the molecules take to collide. Since the ordinary motion of molecules in liquids and gases is hundreds of meters per second—something like the speed of sound—and intermolecular spacing is nanometers or micrometers, reaction times are typically measured in the nanoseconds or microseconds. If two molecules are truly reactive towards each other, then they will react very fast indeed. Fluorine and hydrogen, for example, react spontaneously and explosively in microseconds.

      But there are exceptions. One of the slowest reactions you are likely ever to observes is the...

    • 10. DELAY-LINE OSCILLATORS—PASS-THE-PARCEL OSCILLATORS
      (pp. 322-327)

      What we have here is an early example of a feedback oscillator—one drawn from ancient philosophy rather than modern electronics. Its modern equivalent would be something like the “Song that Never Ends.” Epimenides appears to be about 50 percent liar and 50 percent Cretan. Maybe his mother was from Crete and his father from some place like Athens. And maybe the ancient Greeks would have claimed that in Athens everyone always tells the truth! We’ll probably never know the full story, alas. But we can still have some fun with the concept.

      In fact, in the early days of...

    • 11. THE FAN FLAP FLIP-FLOP CLOCK—A HUFFING AND PUFFING CLOCK
      (pp. 328-332)

      In this section we venture once again into the on and off and on and off again world of oscillators. We will set up a rather unusual oscillator that relies on the air current from afanblowing aflap(or anemometer sensor), which in turnflipsthe oscillator into its off state, until the air stream stops and allows the oscillator toflopback into life again. The fan and flap form a kind of weird delay line—in which the element of delay is the propagation of a puff of air. There is negative feedback: after the motor...

    • 12. THE FAUCET OSCILLATOR—MEASURING TIME WITH SPURTS OF WATER
      (pp. 333-337)

      Pulsating jets of water are at the heart of a number of simple and useful devices in which there is a single moving part—perhaps a simple check-valve—or even no moving parts at all. The hydraulic rams used for supplying water to houses are an example. They work by pulsing a fast-flowing stream of water into a pneumatic bell, which results in relatively high-pressure pulsations that can pump a small amount of water up a high hill. The energy of the large low-pressure flow of the input stream is in effect concentrated into a small high-pressure output flow. Pulsed...

    • 13. THE SLUGULATOR—NOT AN OSCILLATOR FOR THE IMPATIENT!
      (pp. 338-343)

      There is a something undeniably fascinating about a slow clock. Perhaps it gives our short-lived human minds a glimpse into the aeons of existence of the universe. Or is it, as Michael Frayn suggests, that we think a slow clock will allow us to see that fleeting instant that lies betwixt past and future. Or perhaps it has to do with the age-old human obsession with perpetual motion. Even when not pursued in the interests of financial gain, perpetual motion has fascinated inventors since at least medieval times (see box).

      The Slugulator is an RC electronic oscillator based on electrolytic...

    • 14. THE SLOSHULATOR—TIME FROM WAVES
      (pp. 344-350)

      Ever since Archimedes’ day, time spent in bathtubs has been valuable to physics researchers. The (apocryphal) story goes that Archimedes finally solved a knotty problem that the king had posed to him while relaxing in the tub in ancient Syracuse.** When the answer dawned on him, he yelled “Eureka!,” leapt out of the tub, and ran naked through the streets. Go to modern Syracuse and you will find a stone bathtub celebrating that pivotal moment in history

      Those of you who are reading this book in the bathtub are perfectly placed to carry out sloshing as an experiment. No further...

  9. GEEKONICS—SIMPLER THAN YOU MIGHT EXPECT, AND NOT JUST FOR GEEKS
    • 1. THE TELEBUBBLEGRAPH—SENDING BUBBLY MESSAGES THE ELECTROLYTIC WAY
      (pp. 353-360)

      If you leave out the odd letter from a sentence, it rarely stops the listener from understanding what you are saying, although the Reverend Spooner did cause plenty of comic confusion with his famous slips of the tongue. In this project, letters form in an almost magical way in murky water. In this experiment, aided by the valuable human ability to see through a certain amount of error, you should be able to demonstrate a peculiar kind of telegraphy (long-distance communication). Curiously this system of telegraphy, or something very like it, could well have become the world’s first means of...

    • 2. THE TOUCHY-FEELY SENSOR—PUTTING A NUMBER TO HOTFEELINGNESS AND COLDFEELINGNESS
      (pp. 361-367)

      Go to a hot dry place like Phoenix, Arizona, and it generally feels a little cooler than New Orleans, even though the thermometer will tell you that Phoenix is hotter. It comes down to humidity. In a Finnish sauna room, it only takes a moment to try this out. Warm the sauna up to a comfortably hot temperature, then splash a little water onto the hot stones—and it will feel a whole lot hotter almost instantly, even though the thermometer says it is cooler. This is because the human body relies on the evaporation of sweat from the skin....

    • 3. FIRE WIRE—FINDING FIRE ALONG A WIRE
      (pp. 368-374)

      Fire has been vital to civilization ever since the Stone Age. It is with fire that we keep ourselves warm in winter, it is with fire that we create iron and steel, chemicals, and many of the materials of everyday civilization. But mankind has an ambivalent relationship with fire. It is also the destroyer of lives, of houses, of works of art, and also, occasionally, of knowledge. In Bradbury’s dystopia, books are targeted for burning and firefighters set fires rather than putting them out.

      All this history means that the detection and location of fires has been studied for a...

    • 4. ELECTRIC BUBBLE MEMORY—MINUTE ELECTRIC CELLS KEEP YOUR 1s AND 0s SAFE
      (pp. 375-380)

      The central processor unit is usually thought of as the real brains of a computer: the place where instructions are processed, where data is added, multiplied, or otherwise manipulated. However, it is to a less glamorous part of the computer, the memory, that much of the ingenuity of the global computer industry has been devoted over the years.

      Early computer designers, for example, swiftly adopted the spinning magnetic disk as the main memory system. Although it has been through many generations of development, we still use this basic system today. It is capable of storing almost unimaginable amounts of data....

    • 5. RED-HOT MEMORY—BINARY MEMORY: 0s ARE COLD AND 1s ARE (OUCH!) HOT
      (pp. 381-389)

      From everyday experience with electric circuits, you may be used the idea that the resistance of a piece of wire, a motor, a heater or a resistor does not change with temperature. For many purposes, resistance does not change much with temperature, which is one of the reasons why measuring resistance is a useful thing to do. However, for a special class of resistor called a “thermistor,” resistance is not even remotely constant as temperature changes. A positive temperature coefficient (PTC) thermistor is one in which the resistance increases with temperature, while a negative temperature coefficient (NTC) thermistor behaves in...

    • 6. DEFLATION DETECTION—ULTRASONIC TIRE MONITORING
      (pp. 390-396)

      Ever since Mr. Dunlop devised his pneumatic rubber tire, people have had trouble with punctures. You might wonder why we bother to have to inflatable tires. Why not just use solid tires? Well, there is a problem with solid tires. As a wheel rotates, a piece of a solid tire would be compressed briefly, and it would absorb energy while compressed. If it gave back all the energy it absorbed, there would be no problem. However, most soft and resilient solid substances, including rubber, don’t return all the energy of compression. If you could make tires out of steel or...

  10. MAD, BAD, AND DANGEROUS—PROJECTS THAT HAVE HAZARDS, ALTHOUGH THEY CAN BE MINIMIZED
    • 1. DEEP IMPACT—ARMOR-PIERCING CARROTS: HIGH-SPEED VEGETABLES
      (pp. 399-408)

      Agamemnon and the other heroes of ancient Greece described by Homer may have worn bronze armor in the siege of Troy. Armor was invented in ancient times to protect its owner from weapons. But the art and science of war does not stand still. Weapons were then further developed in an effort to pierce armor. And then armor needed to be improved to resist the improved weapons. Bronze was replaced by iron, iron by steel, in both weapons and armor. So it went throughout history, as countermeasure succeeded measure in a slow but inevitable escalation. Even today, when there are...

    • 2. THE FLYING SODA BOTTLE—A SPECTACULAR PIECE OF PRACTICAL SCIENCE USING THE RAPID RELEASE OF ENERGY FROM COMPRESSED GAS
      (pp. 409-418)

      The classic way to launch a projectile has always been to put a cannonball or a bullet down a long cylinder, the blind end of which is packed with an explosive like black powder. First used by the Chinese, cannons made their appearance in Europe as early as the Battle of Crecy in 1346. (Archeologists have unearthed 1½-lb cannonballs on the battlefield). Cannons were slowly improved and standardized over the course of the Middle Ages, a process seems to have been painfully slow in comparison to the pace of modern development. The powder cartridge had evolved by the Victorian era,...

    • 3. OXYGEN FIREWORKS—THE GREENER, SAFER GROUND FIREWORKS SYSTEM
      (pp. 419-430)

      Fireworks are typically made using a gunpowder-like mixture, a fuel such as carbon and/or sulfur with a solid oxidant such as potassium nitrate. They have probably been entertaining humans and frightening horses since the late first millenium, quite possibly originating in China or India in the 800s. Judging from contemporary descriptions, it would seem that for many years they were prized mainly for the explosive bang, rather than for any other effects. Perhaps this is not too surprising, bearing in mind that fireworks were expensive and exotic in their first centuries. And after all, colored flame and smoke were not...

  11. GREAT STUFF—BIGGER PROJECTS THAT NEED SPACE AND LARGER PARTS
    • 1. THE HELEVATOR—THE ELEVATOR OF OZ: IS IT A HELICOPTER OR AN ELEVATOR?
      (pp. 433-440)

      Elevators (aka “lifts”) are an example of technology that only became accepted and widely used after a considerable amount of engineering had gone into ensuring that it was safe. The standard history of a really new technology, leastways of one that arose in the Victorian era, seems to involve a whole bunch of accidents and problems. Accidents and problems and the grumbling they caused continued for years and years, and the bugs didn’t really get worked out until the new system was already widespread. Elevators have been used since the days of ancient Rome, if not before. The arena in...

    • 2. AN AIRBAG OSCILLATOR—YOUR BODY FORMS PART OF THIS RIDE-ON BROBDINGNAGIAN OSCILLATOR
      (pp. 441-448)

      Electronic oscillators are very important to us today. All radio or wireless devices—both the transmitters and the receivers—use an oscillator. Oscillators lie at the heart of ultrasonic technology in medicine and echo-sounding. The heartbeat of a computer is provided by an oscillator. But all of these oscillators are tucked away inside small enigmatic boxes of small enigmatic components that just seem to sit there doing nothing that anyone can discern. They are in fact so small that we speak of them as microelectronics—electronics so small that their component parts are only visible under a powerful microscope. And...

    • 3. A BUBBLE-TUBE OSCILLATOR—TRAINS OF BUBBLES CHASE EACH OTHER UPWARD
      (pp. 449-456)

      William Congreve is best known for his work in rocketry. He was responsible for the setting up of the Rocket Brigade of the nineteenth-century British Army, and so, indirectly, for the “rocket’s red glare” that features in “The Star-Spangled Banner.” He was also known for his curious rolling-ball clocks. Popular with amateur metal workers, Congreve clocks use one or more polished steel balls that roll down multiple inclined planes or tracks as their time-keeping element. At the end of each plane, the ball slows almost to a stop momentarily because of a sharp turn in the track. In this way...

    • 4. THE PREPOSTEROUSLY BIG PARTY BLOWOUT—THE HOLIDAY PARTY FAVORITE SCALED UP TO SPAN FOOTBALL FIELDS
      (pp. 457-462)

      The history of party blowouts is probably tied up with the history of other party novelties, such as the traditional British Christmas cracker (a small firework that lets off a bang and shoots out a small gift when it explodes). The Tom Smith company in London invented the Christmas cracker in 1847 to supplement their sales of other Christmas specials like wrapped sugar almonds, and it seems likely that the party blowout was also a Victorian-period invention.

      To anyone unfamiliar with the party blowout, it is a flattened tube that stays wound up in a spiral, held by an internal...

    • 5. PINK-NOISE PIPES—MAKE MUSIC FROM NOISE!
      (pp. 463-468)

      White noise is a completely random jumbled set of sound waves that normally make a kind of slush of noise, like you get from a TV without an antenna. It contains no particular favored frequency or rhythm; in fact, it contains little snatches of all frequencies and rhythms. Along the same lines as the infinite monkey theory is the proposition that the white noise from a thousand TVs may just once in a thousand years—by blind chance—include a minute or two of a Beethoven symphony or a Verdi aria. In this experiment, we’ll lend a helping hand to...

    • 6. TURBO PANJANDRUMS—THE AUTO-UNICYCLE
      (pp. 469-476)

      The original Panjandrum was devised as a simple, low-cost device in which guncotton rockets would drive the perimeter of two huge, roughly-made wheels, carrying a large bomb on their connecting axle. It was, in a sense, a terrestrial equivalent of the famous bouncing bomb invented by Barnes Wallis and used to attack battleships and dams in Nazi Germany.

      The Panjandrum was designed to breach the Atlantic Wall defenses erected during the Nazi occupation of France in 1940–1944. The idea was that the whole contrivance would drive out of a landing craft and up the fairly gentle slope of the...

    • 7. THE IMPOSSIBLE TURBINE—THE BACKWARD-FORWARD-ALWAYS-CLOCKWISE TURBINE
      (pp. 477-482)

      The energy industry of Planet Earth has a huge problem just around the corner. As the wealth of people in developing countries increases, those people will need more energy. Hitherto, most of the world’s energy has come from so-called fossil fuels, the coal, oil, and gas reserves built up in the Earth’s crust by aeons of decaying vegetation. These reserves will become depleted eventually, which will be a problem for our grandchildren. But, even worse, burning these fuels seems to be adding carbon dioxide to the atmosphere in such large quantities that global warming is taking place. This will lead...

    • 8. A ROCKET RAILROAD—THIS ROCKET PUMPS PROPELLANT FROM THE TRACK AS IT GOES ALONG
      (pp. 483-488)

      The railroad principle has a long history. The very first railroads were those propelled by human-power to get ores out of mines—particularly from horizontal mineshafts, or adits. Horse-drawn lines were developed for large adits and were useful, but limited in capacity. A typical train moved less than ten or twenty tons at only four miles per hour. There was soon interest in other ways of powering trains: first stationary steam engines pulling cars by ropes were tried, and then, later, locomotive steam engines came along and the railroad system something like that we recognize today came into being.

      The...

    • 9. THE HOVERTRAIN—A RAILROAD WITHOUT RAILS
      (pp. 489-495)

      Hovercraft have unique amphibious abilities. They can race across the sea and then, uncannily, go straight up a beach. This sounds awfully useful, so why don’t we see more of them? Why don’t we find them nipping down the road, skipping across a lake or two, then parking at the shopping mall? Well, the main problem is that hovercraft are difficult beasts to tame, in at least two ways: they don’t like going up hills, and they don’t like going around corners. The hill problem is mostly one of power, admittedly: with a powerful enough fan, you could manage ordinary...

    • 10. A JET-WASH ROCKET—THE SUPERCLEAN ROCKET
      (pp. 496-502)

      In the future, space travel may not be 100 percent dependant, as it is today, on the chemical propulsion that enjoyed its finest hour during the Apollo program. A few recent spacecraft have demonstrated one possible alternative: ion thrusters that use accelerated krypton and xenon ions can be deployed to move a satellite slowly from orbit to orbit, or to maintain it precisely in position over a period of months or years.

      Launching from the Moon or from Mars may be possible, for example, using magnetic catapults, while slowish journeys in the nearer parts of our solar system may one...

    • 11. THE SINGLE-HELIX PUMP—YOU DON’T NEED A DOUBLE HELIX TO SQUIRT WATER AT SURPRISING PRESSURE
      (pp. 503-508)

      A U-tube manometer is probably one of the simplest instruments in science: a vertical U-shape of clear tubing, half filled with a liquid, often water, with a ruler running up behind it. If you apply an air-pressure difference between the two tubing ends, then the liquid moves and you can read off the pressure as a change in the level of one or another of the liquid surfaces.

      But what happens if you connect one manometer to another manometer, and then put pressure on the pair? Does one go up and the other stay where it is? Do both go...

    • 12. LEONARDO’S BRIDGE—NO NAILS OR SCREWS OR STRING: IT’S JUST A SUBTLE STACK OF STICKS
      (pp. 509-516)

      You don’t have to read far into the history of science and technology before the name Leonardo da Vinci turns up. Vinci is a small village in northern Italy, and Leonardo was the son of a notary and a peasant there. He was apprenticed early to one of the high technologies of his day—painting. In the late 1400s the art of painting had just had a huge injection of mathematics and chemistry: the math was three-dimensional projective geometry, which gave perspective and depth to pictures, and the chemical development came in the form of new pigments and drying oils,...

    • 13. YOUR PERSONAL HOVERCRAFT—YOU HAVE A PERSONAL COMPUTER, WHY NOT RIDE AROUND ON YOUR PERSONAL HOVERCRAFT?
      (pp. 517-526)

      The hovercraft is arguably the most recent great invention of the transport industry on Planet Earth. The Segway or something like it may yet break through to the mainstream and take its place, but for the moment, I think the hovercraft still has the laurels.

      Although everyone knows about hovercraft, many have yet to ride on one. There are thousands of hovercraft in civilian passenger service, providing transport across mud flats and for short sea crossings around the world. However, they are still relatively rare beasts. Which makes a project to produce a simple working Personal Hovercraft that you can...

  12. TIPS AND TRICKS
    (pp. 527-530)
  13. OLD-FASHIONED UNITS
    (pp. 531-532)
  14. BIBLIOGRAPHY
    (pp. 533-538)
  15. INDEX
    (pp. 539-546)