what lead to the invention of the gear based clock
CLOCKS: FROM GEARS . . .
Information technology is one of culture's most enduring technologies. The mechanical clock was invented in the 13th century, perfected in the 17th and has remained essentially unimproved upon well into the 20th. I have a clock on my mantel that was manufactured the year Abraham Lincoln died. It keeps time to within a infinitesimal a week. A clock is basically a machine that makes a manus movement around in a circle. To create one, you begin by finding some simple mechanical device that generates rotary power. I method is to wind a string around a horizontal cylinder and attach the end of the string to a heavy weight. As the weight drops, the cylinder spins. A less cumbersome method is to use a coiled metal spring, the kind that looks like a spiral. At its within end, y'all attach the spring to an beam. Fasten the other end of the spring to something immobile. At present twist the axle a few dozen times in a counterclockwise direction. The bound coils and tightens. Spike clock hands to the end of the axle. Let go. The hands move effectually in a clockwise circle. Voila, a clock! There is, of course, one small problem. The easily volition whiz around in a mistiness. If this clock represented the pace of history, the unabridged Civil War would have occurred on a Thursday. Therefore, a arrangement must be contrived to really, actually tiresome the speed with which the spring unwinds and, moreover, to slow information technology to the betoken that the hands are moving at precisely one revolution an hour. This is less complex than it seems. Visit a playground. Report a seesaw, a swing set and a bicycle. All of the principles are there. You already accept a mechanical engine spinning an axle. At present y'all have to regulate it with a device that operates at a constant speed. For iii centuries, clockmakers tried various contraptions, none of which was peculiarly reliable. And so Galileo, the Italian physicist and astronomer, discovered something amazing -- the principle of the backyard swing. He noticed that, if you took an object and dangled it at the finish of a cord, and so gave the object a push, it would move back and forth in a remarkably regular blueprint. A gentle push made the object swing slowly. A difficult push made it swing faster. Simply as long as you did not vary the length of the cord, an object of any mass would take precisely the aforementioned corporeality of time to swing from one terminate of its arc to the other. Only the size of the arc would vary. This is chosen pendular motility. {See analogy below.} For half a century, this information sort of just sabbatum around, an interesting but useless curiosity, like the lava lamp. And then in the 1600s, a Dutch astronomer named Christian Huygens, the man who discovered the rings of Saturn, realized that the pendulum was the perfect instrument to regulate a clock. Why astronomers? Astronomers were forever inventing timekeeping devices because celestial bodies were God's clocks. Huygens slowed the circular activity of the clock'southward leap by linking it to the dorsum-and-forth movement of the pendulum. Here's how: The spring-driven central axle is continued through a series of simple gears to a final gear, or "escape cycle," which is trying to spin as fast as it can. Information technology wants to party! But right next to it is a killjoy. It is a pocket-sized metal piece called the "anchor," and it is like your goody-two-shoes older sister. It slows the escape bicycle. The anchor looks similar a miniature seesaw with a prong sticking up at each finish. The prongs alternately rock toward and away from the escape bike. Each time ane of the prongs meets the cycle, it pushes up betwixt two teeth, halting the wheel's rotation. And so that prong rocks back away from the tooth, and the escape wheel turns a little, happily free, though just for an instant. And then the other prong rocks upwards into the escape bike and hits another tooth. So the escape wheel is permitted to rotate but only slowly, tooth by tooth. Each time prong and tooth collide, at that place is the audible tick of metal hitting metal. Or, sometimes, a tock. This is the heartbeat of the mechanical clock. But what makes the seesaw rock? A stiff metal wire called the "crutch" runs from the ballast to the pendulum, which is at the bottom of the clock and swings incessantly back and forth. The pendulum is ho-hum. It's similar a professional yodeler. Information technology knows how to practice simply one affair. But information technology does that one thing very well. You no doubt still accept questions: (i) If you created a pendulum past dangling, say, a Krispy Kreme donut at the end a cord, the donut would move back and forth in increasingly weak arcs until it stopped. Then the dog would eat information technology. Why doesn't the clock'south pendulum keep slowing and stopping, too? Because there is a symbiotic, give-and-have relationship between the pendulum and the clock'south gears. When the escape wheel strikes the anchor and creates the tick, this impulse travels down the crutch and gives the pendulum the slightest push, just plenty to keep information technology going. It is like pushing a child on a swing. To go on information technology going, you just need to administer the tiniest shove at the apex of its arc. (2) Only as the spring unwinds and no longer is really tight, it becomes a trivial weaker. Why doesn't the clock gradually slow downward? The pendulum might go slower, but its swing will get correspondingly smaller, besides. The fourth dimension required for it to movement dorsum and forth volition not vary. That'south all that matters to the clockmaker. A pendulum makes up for lots of errors, including imprecise clock repairing. Clockmakers honey pendulums. "They are very forgiving," says horologist Edward Compton of Ecker's Clock and Watch Shop in Bethesda. (iii) The escape cycle may be moving slowly, but if it moves a little with every tick of the clock, it nevertheless is moving faster than clock hands. How does the clockmaker set up information technology so the easily are moving at exactly the speed of time? This works on the principle of the bicycle. If the wheels of the bike spun at the same speed as the pedals you are pushing, every cycle would exist, in result, a tricycle and you lot might as well utilize a pogo stick or crab-walk on your knees and elbows. The trip would accept forever. The thing that distinguishes a bicycle from a trike is that a bicycle uses higher gears to speed the cycle'southward round move relative to the pedals. A clock uses that principle, besides, just in reverse, to slow things. To slow rotary motility, yous brand the drive gear mesh with a another gear that has more teeth. Considering this new gear will accept longer to consummate one revolution, it volition exist moving more slowly. In a clock, as long as the original gear is moving at a constant speed (nosotros have taken care of that already), by varying the relative numbers of teeth in the next gear, yous tin make that new gear move at any speed you want, including 1 revolution an hour. This is the gear to which the minute hand is fastened. The 60 minutes paw is attached to a gear that rotates at 1-twelfth the speed of the minute hand. (five) Okay, but how can you adjust this clock precisely? What if it needs to run a piddling faster, or slower? Clocks do showroom small variations in their timekeeping, caused by thickening of lubricant, diff wearable of the gears, etc. But it is non a problem. You lot compensate past harnessing the concluding great property of the pendulum. The just way to make the pendulum vary the time of its swing is to increase or decrease the length of the string. Adjust the pendulum down a millimeter or and then, and the clock will run slightly slower. Button the pendulum up, and it speeds up. (six) My non-electronic wristwatch does not announced to have a pendulum. Yet I hear it tick and tock. What'south happening? You lot tin can't strap a pendulum-driven clock to your wrist unless you're prepared to stand up extremely however in the same position forever. So in a watch, the pendulum-and-escapement is replaced past something that looks like a toy gyroscope attached to a thin, coiled hairspring. This device is called a residue ring or wheel. It slows the rotary motion of the escape wheel past oscillating dorsum and along, clockwise then counterclockwise, many times a 2d. At the apex of each rotation, a pin relases the escape wheel, one tooth at a time. Same collision. Aforementioned tick and tock. The design is aboriginal, but hardly primitive. You lot can rely on it. It'southward as regular equally . . . clockwork. Mechanical Timekeeping In a recoil escapement, the teeth "escape" the clutches of the anchor mechanism, one past one, on each swing of the pendulum. Because of the shapes of the teeth and ballast, the bicycle recoils slightly with whatsoever continued move of the pendulum after the ballast and teeth are engaged. The escapement mechanism gives the pendulum a tiny boosting push each time it moves. The deadbeat escapement is designed to eliminate this recoil. Force from the mechanism is conveyed to the pendulum near the center of its swing rather than at either side, increasing accurateness. A pendulum clock is driven by the force of a weight suspended from a pulsate, and the speed of gear rotation is controlled past the escapement. The escapement, in turn, is controlled by the pendulum, whose period -- the swing time for ane complete cycle -- is adamant by its length. A pendulum of .248 meters (9.76 inches) has a period of 1 second. Period increases as the square root of the length, so a pendulum iv times every bit long would have a catamenia of 2 seconds. SOURCES: Encyclopedia Americana (1995), How Things Piece of work Caption: Internal workings of a Swiss spotter. Ruddy spots are rubies, used equally bearings, because their smoothen surfaces offer petty friction and are difficult-wearing.
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Source: https://www.washingtonpost.com/archive/1998/12/09/clocks-from-gears/4652347e-0714-45b7-aea5-5c49fda66d33/
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