Apple II Plus (1979) - Long before the iPhone, the iPod or even the Mac, there was the Apple. Designed by Stephen Wozniak and sold in 1976 with the help of Steve Jobs, the first Apple was a computer strictly for electronics engineers and hobbyists. Although it came fully assembled (unlike the computer kits that began circulating after the invention of the microprocessor), it had no keyboard or power supply and, without a case, all its components could be seen. Nevertheless, interest in the Apple was undeniable. Wozniak and Jobs built dozens of them in a garage in California, in the area well known today as Silicon Valley. To purchase parts, the young men had to sell off some of their most valuable belongings (Wozniak his calculator, Jobs his minibus).

Arc Lamp (circa 1876) - Fire lighted the night for many centuries before humans discovered new ways to illuminate their lives. Near the end of the eighteenth century, Scottish inventor William Murdoch invented gas lighting, which replaced candles, oil lamps and lanterns for certain purposes, such as street lighting. Shortly after Murdoch’s important advance, British chemist Sir Humphry Davy discovered something that would lead to yet another type of lighting — the arc lamp. While working with a large battery, Davy noticed that light leaped across a small gap in the circuit he had built, forming a bright arc. He and other scientists soon began demonstrating this phenomenon for audiences, but arc lighting remained chiefly a curiosity for several decades.

Audion (1906) - Two years after Englishman John Ambrose Fleming invented a two-electrode vacuum tube (commonly called the Fleming valve), American inventor Lee De Forest one-upped him by developing a tube with three electrodes. De Forest, who claimed to have been unfamiliar with Fleming’s work, dubbed his device the Audion, a term he formed by contracting the words “audio” and “ion”. The name De Forest chose for the invention hints at the fact that the Audion detected radio signals, served as a rectifier (a device that converts alternating current to direct current), and was the first solely electronic component to make amplification of electromagnetic signals possible. Its ability to amplify set the Audion apart from the Fleming valve. With his new device, De Forest became a radio pioneer, wirelessly broadcasting music from the Metropolitan Opera House in New York.

Bell Telephone (1876) - By the latter half of the nineteenth century, telegraph lines stretched from coast to coast in the United States and had begun popping up around the world. The revolutionary invention allowed individuals to send and receive coded messages electrically over great distances, but it could not transmit sound, let alone the complex pitches and patterns of human speech.

Coaxial Cable (1929) - In the early 20th century, the United States became increasingly “wired.” Telephone and electrical wires began to crisscross the landscape, connecting homes and businesses. As telephone traffic increased, better wires to carry the calls were needed. AT&T, an American Bell subsidiary formed to provide telephone and long-distance service, constructed its first long-distance network in the late 1800s from copper wiring mounted on telephone poles. Calls passed through the wiring in the form of analog signals. For a single call to be made, two wires were necessary, the first carried the signal one way, the second carried the signal in the opposite direction. Due to the electrical resistance that the signals encountered, early telephone wires, especially those connecting distant locations, were relatively thick.

Davenport Motor (1834) - Some inventions are so ahead of their time that no one appreciates them until long after their inventors’ lives have ended. Today, for example, electric motors, which convert electrical energy into mechanical energy, power our vehicles and appliances such as refrigerators, fans, washers and dryers. But there was a time when the motor was little more than a curiosity.

Davy Electrolysis (1806) - The invention of the voltaic pile – the first primitive battery – at the dawn of the 19th century enabled scientists to conduct experiments that were never possible before possible. Just six weeks after Alessandro Volta demonstrated the pile to the Royal Society of London, English scientists William Nicholson and Anthony Carlisle copied his design to make a voltaic pile of their own. By experimenting with the apparatus, they became the first men to separate water into its component elements —hydrogen and oxygen. Shortly thereafter, English chemist Humphry Davy used a similar process to separate a number of other compounds into their basic components. The process first invented by Nicholson and Carlisle and then perfected by Davy is known as electrolysis, and involves the use of an electric current to cause a chemical reaction.

Duchenne Machine (1850) - Want to know if a smile is sincere? The secret is in the eyes. As Guillaume Benjamin Amand Duchenne discovered through his pioneering studies in electrophysiology, smiles that are the result of true happiness occur spontaneously and involve the muscles around the eyes as well as those of the mouth. This type of smile is known today as a “Duchenne smile.” When someone puts on a perfunctory smile, like those found in class photos or on the faces of store greeters, the muscles surrounding the eyes play no part. Because the muscle movement in a Duchenne smile is involuntary, it is very difficult to fake.

Early Chinese Compass (400 BC) - Knowing what direction you are facing is a very valuable piece of information. This is especially true if you are traveling: because you can use the information to help find your way or guide your safe return. There’s nothing much worse than getting hopelessly lost in the woods or successfully exploring a new frontier, only to find that you have no idea how to make it back home. Such problems were much more common before the invention of the compass, an instrument that indicates direction. Before the compass, people had to rely on landmarks, constellations, or other visual means to help steer them in the right direction. This, of course, caused difficulties under less than ideal circumstances, such as a cloudy night or a dense fog.

Edison Battery (1903) - Since fossil fuels are finite, many automotive experts predict that in a matter of years most cars will run on batteries. If that is the case, it won't be the first time electric cars have ruled the road. When the automobile was introduced late in the 19th century, the gasoline-powered version was the least popular due to its unreliability. Electric cars outsold their internal combustion counterparts as motorists thought these vehicles presented fewer problems.

Electric Range (1892) - To find the origin of the stove, one must go back to dynastic China. The first known cooking apparatus that completely enclosed a fire was built from clay during the Qin dynasty (221 - 207 B.C.). A few thousand miles to the west, the first record of a stove in Europe occurs in 1490 in the town of Alsace, France.

Electrocardiograph (1903) - If television medical dramas have taught us anything, it's how to recognize the heart's characteristic peaks and valleys (or, more often, ominously flat lines) crawling across monitors in emergency rooms or speeding ambulances. These images represent the electrical activity of the beating heart as recorded by an electrocardiograph, a machine that revolutionized diagnostic cardiology and even helped garner a Nobel Prize.

Electrophorus (1764) - A groundbreaking instrument, the electrophorus can be used to produce a considerable amount of electric charge over and over again. Swedish physicist Johannes Wilcke invented the device in the 1760s. Then in the following decade Alessandro Volta improved its design and coined the name by which it is now known. Because it provided a renewable source of charge, the electrophorus quickly became popular in scientific laboratories in the 18th century. Scientists who often referred to it as the “perpetual electrophorus” could use the charge to carry out experiments or to perform electrostatic demonstrations.

Electrostatic Generator (1706) - The earliest methods of producing static electricity involved little more than rubbing two objects, such as amber and a person’s hand, together. The ancients found the phenomenon mystifying and pondered its nature, but never studied it in what we would today consider a truly scientific manner. The development of more complex approaches of inquiry accompanied the rise of experimentalism; in order to adequately study static electricity, scientists first needed to produce sizable amounts of it. Experimentalists also benefited from the consistency new instruments often offered, since the ability to reproduce results is key to good science.

Fluorescent Lamps (1934) - Today fluorescent lamps light up our lives. They illuminate stores, streets and offices, and are even becoming common for certain uses in homes. Compared to incandescent lamps, fluorescent lamps last longer, require less energy and produce less heat, advantages resulting from the different way in which they generate light.

Geiger Counter (1908) - In the early 20th century, many scientists were looking for ways to measure radiation, which had been discovered near the end of the previous century. Radioactivity is the spontaneous emission of radiation (waves or subatomic particles) exhibited by certain elements due to either the unstable nuclei of its atoms or a nuclear reaction. To investigate radioactivity adequately, researchers needed to detect and quantify radiation. There was, however, one problem: Radiation cannot be detected by the unaided human senses.

Gold Leaf Electropscope (1787) - An electroscope is a device used to detect an electric charge. For centuries, it was one of the most popular instruments used by scientists to study electricity. William Gilbert, an English physician and renowned author of De Magnete (“On the Magnet”), built an early form of the electroscope in the early 17th century. His device, dubbed the versorium, consisted of a lightweight needle balanced on a pivot. The presence of electricity in a nearby object caused the needle to move. With the versorium, Gilbert carried out a number of experiments and proved that many materials besides amber acquire a charge when rubbed.

Hydroelectric Power Station (1882) - After Thomas Edison introduced the incandescent light bulb in the United States, he needed a way to provide power to a growing customer base. He built his first commercial power station in New York City in 1882. Steam provided power to the Pearl Street station, but soon other sources of power were explored. Water, used to produce mechanical power at least since the days of ancient Rome, was a logical next choice. After all, many factories in the late 1800s were already using large water wheels to mechanically power their machines.

Iconoscope (1923) - The iconoscope was an early electronic camera tube used to scan an image for the transmission of television. No other practical television scanning device prior to it was completely electronic, although some, such as the Nipkow disc, combined electronic elements with mechanical ones. Within glass housing, the iconoscope contained a photosensitive plate or “mosaic,” which divided the image to be televised into tiny sections called pixels. An electron gun, also placed in the housing, projected a scanning beam of electrons toward the plate. Deflecting coils directed the electron beam, which charged the plate’s pixels. The charge of individual pixels was proportional to the brightness of light initially focused on them, so that the electrical signal produced derived from the original image. From the output of the camera tube, the signal traveled to an amplifier before being transmitted to a receiver.

Kettle (1891) - Up to the 1920s, if you wanted to boil water, you needed an open fire and a kettle. Vessels almost identical to modern kettles, from the shape of the body to the spout, were used in Mesopotamia as far back as 3500 B.C. Time-consuming and inefficient, it was nonetheless the only way to heat water for several millennia.

Leclanché Cell (1866) - Everybody knows that in 1492 Columbus sailed the ocean blue. But did you know that in 1866 Georges Leclanché invented the battery for your favorite gadgets? While that rhyme probably won't make its way into history books, the invention of the Leclanché cell by the French engineer of the same name certainly did. This device, with only minor changes to its original design, evolved into modern alkaline batteries and the most popular household battery to date.

Leyden Jars (1745) - Catching and storing electricity is harder than catching fireflies, but both often involve jars! The first device invented that could acquire electric charge and store it until a scientist wanted to use it for an experiment or demonstration was a Leyden jar. Named for one of the universities (University of Leiden) at which it was first used for research, the Leyden jar was developed independently in the middle of the 18th century by E. Georg von Kleist in Germany and by Pieter van Musschenbroek in the Netherlands.

Lodestone (600 BC) - Lodestone (also spelled loadstone) is a special type of the mineral magnetite. All varieties of magnetite display signs of magnetism, but of them, only lodestone possesses distinctly north-south polarity. Lodestone and other magnetic iron ores often occur in igneous and metamorphic rocks found around the world.

Maglev Trains (1984) - Following its humble beginnings in the early 19th century, the train has evolved into a high-tech marvel capable of speeds in excess of 360 mph. Such unheard-of velocity is made possible through magnetic levitation, or maglev, and trains are the first practical use of the technology in transportation. Anyone who has ever handled magnets knows that opposite poles attract and similar poles repel, which happens to be the fundamental basis of electromagnetic propulsion.

Magnetic Core Memory (1949) - In the rapidly evolving world of computers, critical components often follow a path from cutting-edge to obsolete in short order. There are occasions, however, when a key mechanism displays prolonged staying power. One such example is magnetic core memory. As one of the first stages of random access computer memory, it features tiny, circular ceramic structures (known as cores), all of which contain data and are linked by a network of wires. This storage system is commonly referred to as "core."

Magneto (1832) - The first magneto was built by French instrument-maker Hippolyte Pixii in 1832 – just one year after Michael Faraday's discovery of the principles of electromagnetic induction. Pixii's hand-crank operated magneto was the first practical generator of electrical current.

Magnetometer (1832) - When scientists need to determine the power or the direction of a magnetic field, whether on Earth or in space, they use a magnetometer. These scientific instruments also are used to calibrate both electromagnets and permanent magnets, as well as to indicate whether a material is magnetized.

Marconi Radio (1897) - Numerous researchers and scientists played key roles in the development and advancement of wireless telegraphy (as radio was known in its infancy), including such celebrated names as Nikola Tesla and Thomas Edison. But the system put forth by Guglielmo Marconi was the first to be widely used.

Morse Telegraph (1844) - The early 1800s marked a time of rapid discovery in the fields of electricity and magnetism. Before long, inventors were actively seeking ways to harness the new knowledge for practical purposes. In 1831, American Joseph Henry demonstrated to his classes at the Albany Academy in New York an electromagnetic means of communication. Known for developing incredibly strong electromagnets, Henry used a battery linked to an electromagnet by a mile of copper wire to ring a bell. In 1832, after accepting a professorship at the College of New Jersey (later Princeton University), he relayed messages from his laboratory to his home via this early form of the telegraph.

Ørsted's Compass (1820) - Compasses had been steering people in the right direction for many centuries when, in the year 1820, one particular compass made a very different sort of revelation to an unsuspecting Danish science professor. The surprising event went down in history as one of the greatest milestones in electricity and magnetism.

Ørsted Satellite (1999) - It's a bird! It's a plane! No, wait … it's the Ørsted satellite! Since February 23, 1999, when it was launched from California, a Danish satellite has been circling the Earth in a low orbit nearly in sync with the sun. Named in honor of Danish physicist Hans Christian Ørsted, who discovered electromagnetism in 1820, Denmark's first satellite is considered a microsatellite (weighing in at just 62 kg), built jointly by several Danish space companies. Once it became operational, the daily oversight and maintenance of the satellite became the responsibility of the company Terma A/S and the Danish Meteorological Institute.

Oscilloscope (1897) - Indispensable in workplaces from medical offices to electronics repair shops to physics labs, the oscilloscope is a versatile and widely used diagnostic instrument. A mechanic may use an oscilloscope to measure engine function, while a medical researcher uses it to monitor heart activity.

Pacemaker (1960) - Scientists, poets, mystics and lay-people alike have long been fascinated by the human heart and, as Van Morrison put it, its “inarticulate speech.” The organ has a rich history as home to the soul, moral compass, seat of emotions and essence of life. Only more recently have we come to understand the heart's electrical pathways, knowledge culminating in the development of an artificial heart regulator called the pacemaker. Shaped by many different hands (and hearts), this life-saving electrical device has steadily improved since the primitive models of the early 1950s, shrinking in size as it grew in reliability, complexity and popularity.

Planté Battery (1859) - In 1800, Alessandro Volta invented the world’s first battery. The following year, after observing his voltaic pile, Napoleon made Volta a count. Six decades later, French physicist Gaston Planté invented the first rechargeable battery. He wasn’t named a count for the feat, but he did leave an enduring legacy in battery history: Just pop the hood of your car.

Schweigger Multiplier (1820) - In 1820, the news that the current traveling through an electrical wire could deflect the magnetic needle of a compass astounded the scientific community. Before Hans Christian Ørsted’s announcement of this discovery, scientists considered electricity and magnetism two distinct phenomena. His findings, however, offered hard evidence that they were somehow related. Trying to figure out the specifics of the relationship between electricity and magnetism suddenly became the focus of many nineteenth century laboratories. To help them accomplish their goal, scientists needed better instruments.

Smoothing Iron (1882) - The electric iron has been around since the 1880s, but as is the case with many modern inventions, it has its roots in ancient history. Circa 400 B.C., Greeks would heat a round bar – known as a goffering iron – and use it to produce pleats on robes. The ancient Romans used devices more similar to the irons of today. One was a level metal paddle in which the user would beat the clothes in the hope the pounding would remove the wrinkles. The ancient Chinese used a scoop that was heated with hot coal or sand and would rub it over clothing to smooth wrinkles.

Sulfur Globe (1660) - In the 17th century, German scientist Otto von Guericke built and carried out experiments with a sulfur globe. He described the globe and its use in Experimenta Nova Magdeburgica de Vacuo Spatio (the same work in which von Guericke discusses his more famous device, the vacuum pump), published in 1672. Several of von Guericke’s experiments with the sulfur globe involved electricity, although he did not discuss them in electrical terms.

Stanley Transformer (1886) - William Stanley designed the first commercial transformer for Westinghouse in 1886. Very high voltages are required to transmit electricity across long distances, but are quite dangerous and not suitable in homes. A transformer makes it possible to step up (increase) the voltage of a current in order to transmit it, then to step it down (decrease) to power lights, appliances, etc. Transformers only work with alternating current and are typically formed from coupled coils of wire wound around a metallic core. Stanley built the core of his transformer from a series of E-shaped plates of iron linked together.

Steam Condensing Engine (1769) - Few inventions have affected human history as much as the steam engine. Without it, there would have been no locomotives, no steamers and no Industrial Revolution. The power the steam engine supplied was closely tied to the changes in technology, culture and economy that took place in much of the Western world during the late 18th and early 19th centuries.

Torsion Balance (1785) - In early investigations of electricity, scientists had few tools to aid them. By the 1780s, devices to generate, store and detect static electricity had been built, but there was no easy way to gauge amounts of static electrical charges. A French engineer with an interest in electricity and magnetism, Charles-Augustin de Coulomb, developed one of the earliest instruments capable of this feat: the torsion balance.

Transatlantic Telegraph Cable (1858) - In the mid 1850s, telegraph cables stretched across much of the United States and England, allowing people within those countries to quickly communicate with one another. If someone wanted to send a message from one of these countries to the other, however, they had to do so the old-fashioned way -- by boat, a process that usually took about two weeks. Clearly a telegraph line connecting the US and England would benefit both nations, but the ocean dividing them seemed too difficult to overcome. That is, to everyone but a young, enthusiastic New Yorker named Cyrus Field, who had made his fortune in paper manufacturing.

Voltaic Pile (1800) - For thousands of years, electricity was an ephemeral phenomenon – there one second and gone the next. Flashes of lightning and static electricity produced naturally or by special electrostatic generators did not last long. In order for scientists to carry out detailed studies of electricity, they needed a reliable and long-lasting source. The invention of the Leyden jar in the mid 1700s was an important step toward this goal. With it, scientists could save electricity until they wanted to use it for an experiment or demonstration. But once they did, the jar needed to be recharged before it could be used again. The voltaic pile, invented by Alessandro Volta in 1800, was the first device to provide a steady supply of electricity.

Wheatstone Bridge (1843) - Ever heard of the Christie bridge? We didn’t think so. Yet that’s what a famous electrical circuit, first devised in the 19th century, would have been called had it been named after its inventor. Instead the apparatus, composed of four resistors, a battery and a galvanometer, was named for the man who popularized it — Sir Charles Wheatstone.