Tuesday, February 21, 2006

for the curious

From, A Short History of Technology: From the Earliest Times to A.D. 1900, by T.K. Derry and Trevor I. Williams, Dover Publications Inc., New York, 1993.
Although batteries were [...] an extremely convenient source of electricity for a great many purposes, the wide-spread use of electricity for heat, light, and power depended upon the development of mechanical methods of generation. The first mechanical generator was shown in Paris within a year of Faraday reading his classic paper to the Royal Society in 1831, by an instrument-maker, Hippolyte Pixii, in whose hand-turned generator the coils were fixed and the horseshoe magnet rotated. But before another year had passed, a machine was demonstrated at a Cambridge meeting of the British Association for the Advancement of Science in which the opposite principle, namely rotation of the coils relative to a fixed magnet, was utilized; this is now general practice. From 1834, at latest, rotating-coil generators were being made commercially in London.

The earliest generators produced alternating current[...]with a frequency depending upon the speed at which the machine was turned. This was looked upon as a most serious disadvantage--partly, at least, because all workers were accustomed tow orking with the direct current provided by batteries--but towards the end of the century it was realized that for large-scale use alternating current had decisive advantages over direct. For the time being, however, the problem of the conversion of alternating into direct current was solved by the invention of the mechanical commutator: a commutator designed by Ampere was fitted to an early generator made by Pixii.

There's a good deal more, such as the heating problems those early generators had, and the realization of self-exitation--that electromagnets could retain enough magnetism to start output from an electric generator, thus ending the need for an external battery or permanent magnets--being generally accepted by 1866. But none of that is really needed to underscore the point.

It should suffice to state that the ring-armature Gramme dynamo (generator) was introduced in 1870; it mostly ran on steam power, which goes to show that truth is stranger than fiction.

And for those desiring a more comprehensive timeline, here is a more succinct account of early electrical devises, appropriately enough, describing the Preconditions for Edison's Lamp.

Miss Sabine Fairweather kindly requests that the oh-so-educated gentlemen will refrain from impugning her research in the future, without the benefit of persuasive evidence. She dislikes wasting time in explaining herself.

1 comment:

Anonymous said...

I had been googling about, picking up some of this information in bits and pieces, and here it is, handed to me with a big red ribbon tied about it. Many thanks!!! You've done well, Lady Holly(cribbed from Star Wars VI-the emperor congratulating Vader on the progress on the second Death Star).
I find it amusing to note that what Ben Franklin called a battery was a series of charged plates; that is, a set of capacitors. He called it that because of the beating he felt he had received when he was shocked by it. Another thing that tickled my funnybone is the fact that a Voltaic pile is exactly that, a pile. The components: silver, zinc, and electrolyte are stacked atop each other.