Wheatstone Bridge: A (Not So) Honorable History

Charles Wheatstone introduced "his" bridge in 1843 but it was first invented in 1833 by Samuel Christie. This is the story of *why* these men invented this device and the convoluted tale of how it got its name.

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Solving the Wheatstone Bridge with voltages and voltmeters:

Solving the Wheatstone Bridge for equivalent resistance:

References:
“great difficulty in adopting” Christie, S “The Bakerian Lecture” (Feb 28, 1833) Proceedings of the Royal Society of London Vol. 123 (1833) p. 95
“the intensity of the current” Christie, S “The Bakerian Lecture” (Feb 28, 1833) Proceedings of the Royal Society of London Vol. 123 (1833) p. 98
“nearly 288,000 miles” Wheatstone, C “An account of some experiments to measure the velocity of electricity” Proceedings of the Royal Society of London vol 3 (Dec 1837) p. 300
“elected as a member of the prestigious Royal Society of London” Proceedings of the Royal Society vol. 3 (Dec 1837) p. 366
“imagine my dismay..” Letter XIV: William Cooke to his mother (Feb 27, 1837) Extracts (1895) p. 19
“the velocity of lightning” ibid
“the glory of Wheatstone’s name…” Clark, L “Memoir of Sir William Fothergill Cooke” (1879) found in Extracts (1895) p. 72
“I found that Mr. Wheatstone…” Cooke quoted in Extracts (1895) p. 890
Jacobi, M “On the application of Electro-magnetism to the moving of Machines” (April 1835) The Annals of Electricity, Magnetism, and Chemistry (Oct 1837) p. 422
“founded on exactly the same principles…” Jacobi, M “On the Principles of Electro-Magnetical Machines” (1840) 10th Meeting of the British Association (1841) p. 21
“has shown me, in his unpublished papers…” Jacobi, M “On the Principles of Electro-Magnetical Machines” (1840) 10th Meeting of the British Association (1841) p. 21
“to determine the practicability…” Wheatstone, C “An Account of Several New Instruments…” Proceedings of the Royal Society vol. 133 p. 303
“differential resistance measurer” Wheatstone, C “An Account of Several New Instruments…” Proceedings of the Royal Society vol. 133 p. 323-4
“differs in mechanical construction…” ibid
“not yet generally understood and admitted” Wheatstone, C “An Account of Several New Instruments…” Proceedings of the Royal Society vol. 133 p. 303
“one of the first…to appreciate the importance of Ohm’s” “Obituary Notices: Charles Wheatstone” Proceedings of the Royal
“Mr. Christie… has described…” Wheatstone, C “An Account of Several New Instruments…” Proceedings of the Royal Society vol. 133 p. 325
“kwaker” according to Stubley, P Calendar of Crime (2014)
“Electric Telegraph Company… quit” Cooke, W The Electric Telegraph: Was it Invented by Professor Wheatstone? (1854) p. 44-8
“Wheatstone’s bridge” Siemens, W “Proposal for a new reproducible Standard Measure of Resistance” (1860) translated and found in The London, Edinburgh and Dublin Philosophical Magazine Forth Series (Jan, 1861) p. 31
“the beautiful arrangement first invented…” Thomson, W “On the Measurement of Electric Resistance” (June 6, 1861) Proceedings of the Royal Society vol. 11 (1862) p. 313

[kevinbyrne]

12:43 -- Jacobi did publish a picture of his rheostat in 1842:
Jacobi, M.H. (1842) "Beschreibung eines verbesserten Voltagometers" (Description of an improved voltagometer)
Bulletin Scientifique publié par l’Académie impériale des sciences de Saint-Pétersbourg, 10: columns 285-288. Three diagrams appear after column 288.

[johncurrie]

When I was a kid, remember my physics teacher muttering darkly that "It isn't Wheastone's bridge, it's a Christie's bridge"...the text-books said otherwise. Thanks for clearing that up!!

[GlennElert]

This is the first time I've heard a Wheatstone story that didn't include the fear of public speaking anecdote — which means I got to learn something. Well done.

[hansvetter]

Kathy! You are just a great story teller! For me that's by far the best way to teach science to the public by telling its history! Thank you!

[jimparrUtube]

The context you use to describe these basics of electricity and magnetism is most enlightening. As-in the true historical machinations and personalities behind these leap-frog discoveries.
Thank you Kathy.

[donberg]

Another home run! I would like to add as an aircraft technician, this concept is used to measure the density of the fuel by weight, using capacitors instead of resistors. The variable capacitance being the fuel compared to a known reference capacitance.

[insightfool]

Lots of theft like this happens from grad students to professors today. It's just really hard to track. This videos are great for being reminded of this re-writing of history by the victors.

[johngee]

As a child of the late 20th Century, I am often humbled by science history. I was taught about electrical voltage, current and the relationship between them (resistance, capacitance and inductance) almost as if Ohm's Law always been understood and accepted since the "beginning of time". It is fascinating to learn how this was not the case and that even among the best and brightest minds of their time, they was much uncertainty, disagreement and debate. It is remarkable that the "idle thoughts" of a handful of curious minds over 150 years ago led to the splitting of atoms, spacecraft that travel the Universe and supercomputers that we can carry around in our pockets.

[mewintle]

Wonderful! Thank you. Knowing the history of inventions is so helpful in really understanding the components!

[DK-hsoz]

As a former EE student, these names, these people are the Hallowed saints of electronics (Voltaire, Ohm, Wheatstone, etc). Thank you so much for bringing them to life, and for showing them to be human; warts, misrepresentations and all.

[theklaus]

This channel is so important. Oh Kathy has new- and I’m learning so much about these achievements! Great. I love this

[aclearlight]

I'm so happy to have discovered this YouTube channel! Wonderful content charmingly presented.

[williamdegnan]

According to my late father the variable resistor was invented by either Sam Rheostat or Sam Potentiometer. When I was very young I just discovered that my father knew everything about inventions. It did surprise me how many inventors were named Sam.

[itsevilbert]

Thanks, never heard of Moritz von Jacobi before, but I did hear of use his Maximum power theorem. Basically always match impedances for maximum power transfer, it is one of those things that is as fundamental as ohms law and taken for granted. In the RF world most circuits are designed to have 50 ohms on their inputs (e.g. reference clocks) and outputs (e.g antennas). In designing high speed address and data buses in computers the impedance of all the transmission lines on the PCB's (Printed Circuit Boards) would all be designed to match the input and output of everything on the buses (e.g. memory, I/O and CPU) which is typically 50 to 60 ohms.

I love your video as always! Thank you.

[banehawi]

Another interesting an energetic presenttion. I worked in the Telephone Company in Ireland many years ago, where we used the Wheatstone bridge to measure the distance to a short circuit in an underground cable.

[JJ]

very nice and helpful to bring their names back to life

[tomschmidt]

Great history lesson, another colorful character in the annals of science. So much for science being solely an intellectual discipline. I was unaware of the history behind the Wheatstone Bridge.

[magmasunburst]

Would be amazing to see film footage of these early "electronic" inventors at work in their laboratories, if only that was possible. Would be great to see close ups of them making all the inventions at the various stages.

[billkeithchannel]

The Wheatstone Bridge was one of the early circuit builds I did as a child using my Heath Kit set from the mid 1970's. The Heath Kit was plastic blocks with a component inside and placed on a LEGO looking base plate. The blocks were then tied together with pin clips and wires to make a circuit. One of the more complicated builds was a 3 transistor radio, multi-meter sound generator, and timing counters.

[airframedent]

New follower here... I've worked in electronics most of my life and understand it as well as the next guy... I guess, but I've only known little snatches here and there of the history behind it all. I love your videos. Gets me closer to something I've always taken for granted.