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repeats this also in his "Manuel du Gralvanisme," which book was one of those that, by order, were to be placed in the library of every Lycée in France.
Ampère, who, as is well known, bestowed most particular attention on the subject, brought, in 1820, before the scientific world through Oersted, mentioned that it might perhaps be possible to make use of the deviation of the needle for telegraphic purposes, but neither he nor any one else then constructed such an instrument.
It was reserved for Baron Schilling, at St. Petersburg, to make the first electro-magnetic telegraph. Having become, as we know, through Soemmerring, at Munich, passionately fond of the art of telegraphing by means of galvanism, he now used for it the deflection of the needle, which he placed within the multiplier of Schweigger horizontally on a light vertical axle hanging on a silken thread, and bearing a circular disc of paper, coloured differently on each side. To make the needle move steadily and prevent oscillations, Schilling had fixed to the lower extremity of its axle a strip of thin platina plate and immersed it in a cup of mercury. By degrees he simplified the apparatus. For a time he used five needles, and, at last, he was able to signalise even with one single needle and multiplier,
