Introduction
In the early days of electrical engineering, electricians had to work with crude and simple materials to generate, store, and transmit electricity. Electricity was a novel field of scientific inquiry, and most electrical devices we take for granted today had yet to be invented. The pioneers of electrical engineering displayed remarkable ingenuity as they coaxed electric currents to flow using the limited tools available in the 19th century. Their crude batteries, wires, and switches paved the way for the widespread adoption of electricity.
Batteries
Thebattery is the cornerstone of any electrical device, ancient or modern. Early electricians used different methods to build crude batteries that could produce electricity:
The Voltaic Pile
In 1800, Alessandro Volta invented the Voltaic pile, one of the first batteries that produced a steady electric current. Volta stacked discs of copper and zinc separated by cardboard soaked in brine to build up power. Although fragile and prone to drying out, the Voltaic pile allowed sustained low voltage electricity generation for the first time.
The Daniell Cell
In 1836, John Frederic Daniell, improved on the Voltaic pile by using two electrolytes - copper sulfate and zinc sulfate. The Daniell cell was more stable and less susceptible to drying out. Daniell cells were adopted commercially to power early telegraphs and similar devices.
The Leclanche Cell
The Leclanche cell was invented in 1866 by Georges Leclanche, who used a combination of carbon and manganese dioxide electrodes in ammonium chloride electrolyte. Leclanche cells were widely adopted as they did not require refilling and could provide 1.5V continuously. The precursor to modern dry cells, Leclanche cells powered early battery-powered devices like flashlights.
Wires
For electricity to be useful, early electricians needed to transmit it efficiently. This required the development of wires that could carry current over long distances:
Iron Wires
Early telegraph systems in the 1830s experimented with using iron wires to carry electric signals, but found they quickly corroded. Miles of unreliable iron telegraph wires had to be constantly replaced at great expense.
Copper Wires
Elisha Gray discovered that copper was a much better conductor than iron and did not corrode as easily. From the 1850s onwards, copper wires became the standard way to transmit electricity in telegraph and later telephone networks. Drawing copper wires was labor intensive, limiting their length.
Aluminum Wires
The availability of cheap aluminum from the late 1880s allowed making wires that were lighter than copper for the same conductivity. Aluminum wires could be produced in much longer continuous lengths, revolutionizing electrical transmission. The first long distance overhead power lines used aluminum wires.
Insulation
For safety as well as minimizing power losses, wires carrying electricity needed proper insulation:
Rubber
Natural rubber was used to insulate early telegraph systems, but had issues with cracking over time. Vulcanization processes invented in the 1840s helped improve the lifespan of rubber insulation.
Waxed Paper
Waxed paper tape wrapped around copper wires formed a cheap readily available insulation material for early electrical systems. As generating voltages increased, waxed paper was not sufficient to prevent shorts and shocks.
Rubber Coated Wires
A combination of technologies allowed creating rubber coated wires - rubber extrusion processes allowed coating wire evenly, while vulcanization cured the rubber into a durable moisture resistant sheath. Thomas Edison's electrical company was the first to supply factory made rubber insulated wires.
Switches
As electrical devices proliferated, controlling and routing electricity flows required the development of switches:
Knife Switches
Early knife switches used metal blades physically inserted between contacts to complete or break a circuit. They had to be manually operated. While crude, knife switches could handle high voltages and were used in early electrical switchboards.
Mercury Switches
Mercury switches used a pool of liquid mercury metal to conduct current between contacts. Tilting the switch changed mercury's position, acting as an on/off control. Mercury switches were common in early appliances, though the toxicity of mercury drove them out of use.
Solenoid Switches
An early electromagnetic relay used a solenoid coil to move a switch mechanically. Energizing the solenoid closed the switch contacts. Solenoid switches allowed remote electrical control of circuits for the first time. Telegraphs used them to route signals.
Conclusion
We owe a debt to the electrical pioneers who managed to wring practical applications out of the most basic of materials. Their innovative and groundbreaking work electrified the world and paved the way for the convenience and abundance electricity provides us today. The principles behind their crude batteries, wires, insulation, and switches underpin our most advanced modern technology and will likely continue to do so for a long time to come.