The rotary dial works on a pulse-based system. The frequency of pulses is determined by the number on the dial which the caller selects, with the user manually turning the dial to a fixed point with their finger before releasing it.

This causes the dial to return to its starting position due to an internal recoil spring, while simultaneously generating a series of electrical pulses that interrupt the flow of current on the telephone’s line.

These pulses correspond to the digit selected, so if the user rotates the dial from, say, ‘7’, then seven pulses will be sent down the line to the switching office.

Inside the body of the phone a centrifugal governor ensures that the dial’s rotation is moderated to a constant rate, with a shaft on the governor turning a cam that opens and closes a switch contact.

If the contact is open, the line’s current is stopped from flowing, thereby creating a dial pulse, while when closed, there is a constant flow of current.

At the electromechanical switching office, these pulses are received by a sender system, which records the pulses – ie the dialed number – before routing it to a selector system which makes the outgoing connection to the telephone of the appropriate property.

The rise of touch-tone

In 1950 US network operator AT&T ran a series of trials which proved that push-button dialing was roughly twice as efficient as rotary dialing.

This led to the company releasing an electronic pushbutton system known as ‘Touch-Tone’ to its customers in 1963, which quickly gained popularity thanks to its speed – both at the user end and at the network end.

The touch-tone system, which is still in use throughout the world today, works through dual-tone multi-frequency (DTMF) signaling where each of the dialing digit buttons is assigned a specific frequency; columns have higher-frequency tones while rows have lower ones. As such, when a button is pressed, a dual-tone signal is generated that corresponds directly to the frequency assigned to a specific telephone number.

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These vibrations were traced onto a sheet of paper coated in soot, which was wrapped around a rotating cylinder. This, however, could not play back the recording.

In 1877, Thomas Edison’s phonograph followed a similar principle to the phonautograph, but used tinfoil wrapped over a grooved cylinder. The vibrations of a needle attached to a diaphragm and horn made indentations in the foil, and to play it back the needle retraced the indentations in the foil. Wax cylinders enabled such recordings to be played back more than once.

Ten years later, Emil Berliner introduced the gramophone that used discs with a spiral groove, rather than a cylinder to record and play back the sound. It still used a horn and needle, but unlike cylinders, the master recording could be easily copied onto a mould and mass-produced. The gramophone came to dominate the market in the Twenties, superseded by the electronic record player.

Anatomy of a gramophone

Pickup head – The needle on the pickup head was commonly made of copper or steel. The needle is attached to a diaphragm that sends the sound vibrations to the horn.

Turntable – This is rotated at a constant speed by a wind-up clock-work mechanism. They usually operated at a speed of 78rpm.

Horn – Amplifies and projects the sound from the needle (stylus). A ball or material was put into the horn to reduce I the sound from the horn.

Spindle – The hole punched in the centre of the record disc is placed over the spindle. This keeps the record from spinning off the turntable as it rotates.

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The first mass-marketed electric washing machine was the Thor, a tumble washer produced by the Hurley Machine Company in 1908.

The machine worked by tumbling clothes with a wooden drum, in two directions, at eight revolutions per minute. The drum’s rotation mechanisms were powered by a single Westinghouse Electric Company electric motor and connected together via drive belts.

Most innovatively, however, the Thor featured an integrated clutch, which allowed the machine to switch revolution direction and also be held in a stationary position once power was supplied. For a closer look at the machine’s inner workings see the diagram to the left.

Inside the Thor electric clothes washer

Spin – The drum turned at eight revolutions per minute before reversing direction to spin again.

Wringer – The machine’s chain-driven wringing mechanism could be reversed through the operation of a top-right-mounted lever.

Drum – The Thor’s drum was made of wood, into which a galvanized tub was inserted to hold clothes.

Clutch – A control lever on the left side of the machine was operated to engage and disengage its clutch.

Read also: How much does it cost to run a washing machine?

Power – Unlike modern machines, the Thor did not have an on/off switch, instead requiring users to physically disconnect its power cord to turn it off.

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The first portable timepieces were pocket watches which were worn on a chain; however, they only had an hour hand and they were terribly inaccurate, often losing several hours a day. Nevertheless, these were very much the commercial Rolexes of their time, ornate items valued primarily as status symbols. They weren’t very popular either, and it took another century before watches became a common sight.

The invention of the balance spring in the mid-17th century, which gave the mainspring a beat that was much more resistant to disturbances, brought with it the minute hand.

Now watches were accurate to around a ten-minute margin for error a day and, with the realization that watches could be used as scientific instruments, throughout the 17th and 18th centuries improvements to the accuracy of the balance spring were facilitated by the scientific community. Jewel bearings were popularized in the early-20th century for accurate timepieces.

The jewels themselves improved the life of the bearings over their brass predecessors, had a low, predictable friction and didn’t need any lubrication. They were patented back in 1704, but the invention of synthetic jewels 200 years later, by Auguste Verneuil, made jewel-bearing watches much more affordable, and so available to the masses. The Fifties saw a steep rise in wristwatch popularity as the first electronic watches came to the fore, with a balance wheel controlled by an electromagnetic solenoid or a tiny tuning fork vibrating at a constant frequency. These particular models were the precursors to the modern quartz watch which is ubiquitous today.

Following the trends

Wristwatches weren’t always a fashion statement like today.

Up until the early-19th century, wristwatches were considered ‘uncool’. In the Western world, pocket watches were a masculine status symbol and wristwatches – or ‘wristlets’ – were considered feminine and incapable of coping with day-to-day life.

That attitude began to change as soldiers discovered wristwatches were far more practical on the battlefield than a pocket watch, though this didn’t come to a head until WWI. Millions of soldiers were given a wristwatch, something more accessible than a pocket watch while they were laden with kit. The war hero, returning home with his standard-issue ‘trench watch’ did much to dispel the image of the girly wristlet. Among the forerunners of the modern wristwatch at this time was Hans Wilsdorf, who strived to improve the design and accuracy of the device and whose company-Rolex – continues to win awards for its precision instruments today.

Modern watches

How today’s watches are ever advancing?

While mechanical watches can still be bought today, they’ve largely been replaced by the quartz watch, which revolutionised the market in 1969.

The original design had a crystal that resonated at a regular 8,192 Hertz, a huge step up in accuracy from the analogue five Hertz that the mechanical balance wheel could achieve. It also removed all moving parts, putting an end to cleaning and improving shock resistance. The second generation of quartz watch technology seen in modern watches often uses low-power LCD displays and has an increased crystal frequency of 32,768 Hertz, with a discrepancy of five to ten seconds a month.

The only watches more accurate than this aren’t self-sufficient: radio-controlled watches use a receiver to pick up radio time signals that regulate the time on a daily basis using the output from an atomic clock, which is accurate to within one second every 30 million years!

First wristwatches

1511 – Taschenuhr

The origin of the mainspring is uncertain, but German clockmaker Peter Henlein began making them around this time and is credited with popularizing portable timepieces. His watch, the Taschenuhr, became a status symbol for the wealthy.

1657 – Balancing act

Again, the original inventor is in contention, but either Robert Hooke or Christiaan Huygens conceived the balance spring. This radically improved a watch’s accuracy by regulating the oscillation of the balance wheel.

1675 – Royal endorsement

The pocket watch was popularized by Charles II. The fashionable king also introduced waistcoats and, as a result, a gentleman’s watch evolved to the flat circular timepiece on a chain, to fit snugly inside the pocket.

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Today, our currency is pressed out of long sheets of metal and stamped under pressures of up to 360 tons per square inch in automated machines. But before Matthew Boulton’s steam-powered minting process and Peter Blondeau’s hand-cranked machinery, coins were struck individually by hand.

Carefully weighed circular blanks of metal from the forge were placed between two hardened metal blocks, one with the reverse design and the obverse design on the other. The top die was then struck hard with a hammer so that the softer metal of the coin blank took on the design on both sides.

The process – which was called milling-was comparatively time-consuming and was also fraught with errors: coins were frequently struck off-centre, double-struck or cracked.

Check also – Ancient coins  and Department of Coins and Medals

Worse still for the authorities, because gold and silver were used in the higher denominations and because no two coins were alike, the act of ‘clipping’ the edges of precious metal coins, or ‘sweating’ silver coins (shaking a bag of silver and collecting the dust), was common practice among the unscrupulous, who could then profit by spending the coin at its face value while pocketing the precious remains.

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Fountain pens work, in general, by transporting ink from a sealed container (usually a cartridge) through a hole, into a finned feed and down to the tip of the nib. As the nib comes into contact with a surface, such as a sheet of paper, the ink is drawn out of the nib through capillary action, causing more ink to be drawn through the feed from the sealed container.

Importantly, as the containers sealed, a vacuum is created within as the ink is removed and this – in partnership with the ink’s surface tension as well as its molecular attraction to the pen’s metal nib – causes it to flow in a controlled and consistent way. It also means the ink ceases to flow when the nib is lifted.

Fountain pen teardown

Nib – The point of contact for the pen, the nib narrowly distributes ink onto a writing medium like paper. Nibs are commonly made from gold plate to avoid corrosion.

Cap – A protective cover for the delicate pen nib, the cap is often installed with a clip for easier portability.

Feed – Arguably the most important part of the pen, the feed controls the flow of ink out of the reservoir and distribution to the nib. The feed on a modern pen is commonly made from hard rubber or vulcanite.

Barrel – The casing for the internal components, the barrel tends to be made from plastic or lightweight metals. It is often tapered for ergonomie purposes.

Reservoir – A sealed container, such as a cartridge, that holds the pen’s ink. Ink is drawn from the reservoir into the feed for controlled distribution.

Section – The lynchpin of the pen, the section holds together all of the various parts within the barrel and cap, including the feed, breather tube and nib.

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Designed by renowned agriculturalist Jethro Tull in 1701, the drill went on to spawn many other mechanized planters and ploughs, which many of today’s agricultural tools and vehicles are descendents of.

The drill – which was made from elm wood and consisted of a wheeled wooden frame -worked by carving three channels into the earth into which seeds were dropped from containers at regular intervals.

The seeds, once dropped by the horse-drawn drill, were then covered by the harrow (a trailing bar), which gathered soil and evenly deposited it over the channels.

Facts about Seed Drill

Seed boxes – Sitting at the bottom of the hoppers, these boxes distributed the seeds at set intervals.

Hoppers – The drill’s hoppers were chute-like containers that held the seeds en masse. They dropped from here into the seed boxes for scattering.

Tines – The tines helped split up earthen clods gathered during operation, ensuring fluidity of movement.

Sheats – Three wooden, angled funnels, which carved the planting channels as well as guided seeds into them from the seed box.

Spindles – The spindles held the drills wheels and hoppers in the correct positions for even distribution.

Harrow – The harrow covered the seeds with soil once deposited in the cut channels.

Standards – The standards held the spindles – and therefore the drill’s wheels – perpendicular to the sheats and level.

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The figures represent the soldiers of Qin Shi Huang, the first emperor of China. They had been placed in his tomb, an earthen pyramid mound, which was excavated beneath Mount Li.

Construction had begun when the emperor was a child – it took many years to build. The tomb represents the royal palace, and the figures Inside, court residents.

Beside the warriors, archaeologists found models of officials and entertainers. There are 8,000 soldiers, each depicted with weapons such as spears, bows and arrows.

There are also models of horses and chariots. Made out of yellow clay, the Terracotta Warriors were meant to protect the emperor In the afterlife.

Artisans first made the limbs and heads which were then fired in a kiln. Once assembled, the models were painted and coated with a preservative, but only some colours are still visible.

Each figure was given individual features, with details added to the hair and clothes; artists even added muscle tone to the arms and legs.

The height of the soldier depended on his rank – ie the military generals are the tallest figures in the group.

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Pianos work by transmitting the vibrational energy of taught wire strings into a soundboard, which in turn converts the vibrational energy into sound.

The piano achieves this through both its construction materials and action mechanisms. Pianos consist of five main parts: the frame, soundboard, strings, hammers and keys. The frame is constructed from metal and serves as a stable, immobile platform from which its strings (metal wires) and soundboard (vibration to sound conversion mechanism) can vibrate efficiently. Steel is used as it helps mitigate unwanted vibrational energy being transmitted to the rest of the piano and surrounding area, a problem that leads to distortion of produced sounds.

The hammers act as a striking mechanism, and when the piano’s keys are pressed by the player, they rise to strike their corresponding strings in order to produce vibrational energy.

The physics of the piano work in a chain-reaction. When a key on the keyboard is pressed, a complex system of Jacks, pivots and levers raise a suspended hammer upwards to strike an overhung string, as well as a string damper (a felt block) that, once the string is stuck, comes into contact with the string and ceases its vibration.

In the short time between the hammer striking the wire and damper ceasing its motion, the vibrational energy is carried down the string and over a ‘bridge’, a raised bridge-shaped structure over which the string is tightly stretched.

The bridge receives this vibrational energy and transfers it into the piano’s soundboard, a wooden board chosen for its resonant properties that through the principle of forced vibration vibrate at exactly the same frequency of the struck string. Consequently, due to the large, expansive size of the board, the quiet tone created by the string is increased, and produces a loud note.

How pianos are made?

Soundboard – The soundboard converts the vibrational energy of struck strings and amplifies their sound.

Hammers – Fixed to the end of the keys through the piano’s mechanism, hammers strike its strings to vibrate them and create sound.

Mechanism – A complex arrangement of wooden and metal pieces that transfer the key pressing action of the player into the striking movement of the hammer.

Pedals – The sustain pedal sustains all notes, the sostenuto sustains certain notes while the una corda shifts the action assembly to the right so multiple strings are stuck by one hammer.

Bridge – Helps transmit the vibrational energy of the strings into the soundboard as efficiently as possible.

Dampers – Felt pads, raised onto strings to stop them vibrating totally, dropped to elongate vibration or positioned for a softening effect.

Strings – High carbon steel strings vibrate when struck. They vary in construction, with bass strings made of steel and wrapped in wire, but vary little in diameter.

Here you can see on other site HOW A PIANO WORKS

Frame – Made from the finest hardwoods and metals, the frame serves as an immobile – but often highly ornate – platform for the soundboard to vibrate within.

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Looms, while appearing rather complex, are actually fundamentally simple machines that work by holding two sets of parallel threads within a frame that alternate with each other as a cross thread is filtered through them carried by a shuttle (a wooden block in which thread can be stored pre-weave).

By doing this cloths and fabrics can be weaved on a large scale quickly and in far greater numbers than if undertaken free form by hand.

Since their initial construction in the 5th Century BC, the basic mechanics of looms have remained unchanged, with only a long succession of improvements introduced to the system.

The most notable addition was the introduction of a drive-shaft power source, allowing for mechanized looms to be mass-produced and slowly evolved to the point of complete automation.

Indeed, today it is argued by historians that the power loom was central to the development of the Industrial Revolution and has contributed greatly to the proliferation of large and high-quality fabrics worldwide.

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