retroelectro
"The science of electricity, and the art of telegraphy, have both now arrived at a stage of progress at which it is necessary that universally received standards of electrical quantities and resistance should be adopted, in order that precise language and measurement may take the place of the empirical rules and ideas now generally prevalent” – Latimer Clark, 1861
Wheatstone used a copper wire of ‘one foot in length and weighing one hundred grains’ as an electrical resistance standard. In the same building, an engineer designing telegraph cables used a standard of ‘a mile of copper wire with a diameter of one-sixteenth inch’ . Early telegrapher manuals may list the length and weight of the copper used as the only useful measurements. The cable manufacturing industry experienced a surge during this period. With numerous players joining the market, there was a buzz of innovation and competition, driving the new electrical industry forward. You could go to any cable manufacturer, and they all sold ‘the best and purist of copper cable’, but there was no established standard to measure this claim against. At the time, this wasn't a big issue because telegraph messages could be sent through almost any length of overhead lines without difficulty.
(charge). Domestically, each country had its own ‘standard.’ Some countries used iron wire in their standard, some used copper wire, and others used gold- alloy wire. It became clear that standardizing the measurement of electrical resistance would be necessary to figure out how to solve the trans-Atlantic cable problem.
1850s - The trans-Atlantic cable By the mid-1850s, man’s telegraphy hubris became an insurmountable obstacle. Between 1850 and 1853, submarine cables were laid from France to Britain and then from Britain to Ireland. In 1854, the concept of a trans-Atlantic cable was becoming trivial in the minds of some. Several attempts were made to connect the New World to the Old World, but their limited understanding of electrical theory and measurements caused one issue after another. Running two thousand miles of heavy conductors through three- mile-deep ocean water at very low temperatures and shoveling two thousand volts of electricity through them may cause problems. Ohm’s Law had been recognized as accurate and practical, so they knew that if they could reckon an absolute measure of resistance, they could model voltaic currents (amperes), electromotive force (voltage), and electrical quantity
by Sir Charles Bright, he starts down the path that will lead to the immortalization of Georg Ohm in the minds of designers, on the tongues of electricians, and within the hearts of every high school physics teacher in the time since by proposing a new committee to study and standardize the measurement of electrical resistance. The following year, the British Association for the Advancement of Science (BAAS) appointed ‘The Committee on Standards of Electrical Resistance’. Members of this committee included Sir
William Thomson (Lord Kelvin), James Clerk Maxwell, Carl Siemens, Sir Charles Wheatstone, and Sir Charles Bright, along with people instrumental in metallurgy, mineralogy, and the design of cable-laying ships. After three years of extensive experimentation, the 1865 Report of the Committee on Standards of Electrical Resistance starts with ‘The Committee has the pleasure of reporting that the object for which they were first appointed has now been accomplished.’ By 1867, the committee had completed the bulk of their work,
and these new standards for resistance revolutionized the entire supply chain, top to bottom. They could now determine the purity of copper based on the length, weight, temperature, and resistance, thus could better model and predict how wire will act in different environments. In 1873, after twelve years of working on this problem, a committee of the British Association for the Advancement of Science formally proposed the ‘ohm’ as the standard unit of measure for electrical resistance.
1860s - The British Association for the Advancement of Science
The year was 1861.
After years of work as a cable engineer, including efforts that lead to improvements on the trans-Atlantic cable, Latimer Clark found himself in front of the British Association for the Advancement of Science in Manchester. Being accompanied
Fun Fact: The first transatlantic cable weighed 1,600 tons, used over 26,000 nautical miles of wire, and took 250 workers a year to make.
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