Information | |
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Number built: | 1 |
Built: | 1842 |
Builder: | Robert Davidson |
Motor: | Battery electric |
After Faraday had shown how electricity could be made to generate mechanical movement, Davidson constructed his own batteries and began his own experiments. By 1837 he had built his own electric motors [2] and used them to power a model railway and a lathe, amongst with other equipment in an exhibition held in 1840 in his native Aberdeen. In 1842 Davidson built the full-size electric locomotive Galvani.
Galvani was powered by large lead zinc batteries with an acid electrolyte [3]. The motor consisted of electromagnets around a revolving log to which were attached iron bars, one log for each axle. A switch turned the electromagnets off when the iron bars were in opposition. Davidson experimented with the number of batteries needed, eventually fitted seventy six cells. Galvani wasn't a tiny machine, it was nearly five metres long and weighed nearly five and a half thousand kilograms. Galvani was powerful enough to haul itself and a coach.
However, Galvani was a technical dead-end. The batteries were single use, rechargable batteries had not yet been invented. Galvani burned through it's batteries like a steam locomotive burned coal, though many times more expensively.
After the unfortunate destruction of Galvani, Davidson was unable to find investors to continue his development. Happily however Davidson was long-lived and in the 1890s was able to see his vision vindicated with the arrival of electric railways like the City & South London Railway. He was "re-discovered" and feted by the press as the inventor of electric railways [5].
Galvani [4] |
Galvani [1] |
[1] "The Earliest Electric Railway", Electrical World Vol. 16 (1890) Jul-Dec p. 276
[2] "Mr Davidson's electro-magnetic experiments", The Mechanics' Magazine, Vol. 33 (1840) p. 92.
[3] R.L. Vickers, DC Electric Trains and Locomotives in the British Isles (David & Charles, 1986) p. 13
[4] T. du Moncel, Electricity as a Motive Power (London, 1883) Fig. 32
[5] John S. Reid, "Robert Davidson - pioneer electrician", The Scientific Tourist: Aberdeen