British engineer James Wimshurst did not invent the machine that bears his name. But thanks to his many improvements to a particular type of electrostatic generator, we now have a Wimshurst influence machine.

What does a Wimshurst machine do?

Influence machines date back to the 18th century. They are a class of generators that convert mechanical work into electrostatic energy through induction. By the middle of the 19th century, German physicists Wilhelm Holtz and August Toepler had developed models with rotating vertical glass disks. It was this type of generator that Wimshurst began fiddling with in his home workshop in the early 1880s. By 1883, he approved his project.

The Wimshurst machine as it exists today has two insulated discs, often made of plastic but sometimes glass, with conductive metal plates at the edges. The discs are mounted on the same axis and rotate in opposite directions under the action of the handle.

As the discs rotate, a small initial charge, positive or negative, on one metal plate will move towards the double-sided brush on the second disc. When the plate aligns with the brush, it will induce an equal and opposite charge on the plate that is directly opposite it on the other disc. The resulting charge, in turn, causes an opposite charge on the plate of the first disk. Meanwhile, the plates on the second disk induce charges on the first disk. Metal collector combs separate the charges into positive and negative and conduct them to two capacitors from a Leyden jar. The build-up eventually discharges with a spark that crosses the gap between the two terminals and the process begins again. The Wimshurst desktop machine can produce up to 50,000 or 60,000 volts, as shown in this video:

Animate It – Wimshurst Machinewww.youtube.com

The simple design was easy to reproduce and use, so Wimshurst machines found their way into laboratories, schools, and even the homes of wealthy Victorians. Because of the high voltage they could produce, machines were used to excite Crookes tubes and generate X-rays for medical imaging in the early 20th century.

When Wimshurst died suddenly at his home on January 3, 1903, at the age of 71, the editors Nature found it worthy of an obituary. Twenty-nine years later, on the centenary of his birth, Nature again published a note, calling him “among the most famous inventors of electrical machines of the last half of the nineteenth century.” And yet, as far as I know, there is no separate complete biography of this person. In fact, most Internet searches return the same set of details as Nature initial reports: He was the son of shipbuilder Henry Wimshurst (a pioneer in the construction of propeller-driven ships). Archimedes); an apprentice at the Thames Iron Works; ship surveyor Lloyd’s Register; from 1865 to 1874 – head of the register of insurers of Liverpool; and finally, for the last 25 years of his working life, until reaching the mandatory retirement age of 67, he was Chief Shipbuilder of the Chamber of Commerce.

James Wimshurst developed the machines of the same name in his spare time. By day he was a ship’s inspector for the British Chamber of Commerce.Antonio Carlos M. de Queiroz/Wikipedia

Wimshurst’s electrical pursuits were entirely a hobby he pursued in his spare time at his home in Clapham, southwest London. With the help of his two sons, he set up a laboratory and workshop where he tinkered with influence machines until he perfected his designs. Wimshurst made over 90 of his eponymous machines. Most of them fit easily on a countertop, for example, this one, kept in the Science Museum in London, measures 56 by 67 by 30.5 centimeters. But he also created one exceptionally large machine, 2.1 meters high, which is on display at the Museum of Science and Industry in Chicago. (The machine pictured above is in the Yale Peabody Museum of Natural History in New Haven, Connecticut. It was made in Germany and sold in the US by James W. Queen & Co.)

Wimshurst never patented any of his machine improvements, but he was eager to talk about his inventions. In 1886 he published a book, Static electricity. “Influence Machine”: how to make it and how to use it. And on April 27, 1888, he gave a lecture on machines at the Royal Institution. Recognized for his scientific achievements, he was elected a Fellow of the Royal Society in 1898. He was also a member of the Institute of Electrical Engineers and the Roentgen Society, and a member of the Board of Governors of the Royal Institution.

But the part of the Wimshurst story that I find most interesting is contained in the last paragraph of the book. Nature obituary: “All of Mr. Wimshurst’s scientific research was carried out out of sheer love for the work, and he steadfastly refused to accept any material benefit from it.” Perhaps that is why historians have not yet written his biography: they do not know how to relate to a truly altruistic inventor.

Try It At Home: Electric Kiss

Wimshurst machines are readily available for purchase today. They are still used today in schools and science museums to demonstrate the basics of electricity. You can also build your own device using items from the hardware store.

In volume 17 of Do magazine (2009), a steampunk enthusiast known as Jake von Slatt described how to build a Wimshurst machine. (Von Slatt also appeared in IEEE SpectrumOctober 2008 article “The Steampunk Contraptors”). His updated instructions are available online as a five-part series.

If you decide to go all out to make your own Wimshurst machine, I suggest the next logical step is to plan a stunt dinner party in a Victorian salon. Instead of playing Monopoly, Trivial Pursuit, or Parchisi again, why not have some fun like the Victorians, who were obviously crazy about electricity.

To be clear, the Victorians were simply continuing a trend that spanned over a century; Ben Franklin also enjoyed entertaining his guests with electric games. Thanks to the simplicity of the Wimshurst machine, partygoers in the 1890s had a reliable source of easily generated electricity.

One popular game was called “electric kissing”: start the Wimshurst machine, ask the courting couple to take hold of one of the capacitors, and have them lean in for a surprise. It’s a little more shocking than spinning a bottle. Although none of the literature I reviewed contained concerns about a kissing couple accidentally electrocuting themselves, Indiana University’s Physics Department website has a warning about a demonstration of a Wimshurst machine: “May cause fatal electric shock when connected to too much a large number of Leyden jars.”

Part continuation of the serieslooking at historical artifacts that reveal the limitless potential of technology.

An abridged version of this article appears in the June 2023 print issue titled Wimshurst’s Electrostatic Immortality.