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Isolated observations by Brugmanns, Becquerel, Le Baillif, Saigy, and Seebeck had indicated the existence of a repulsive force exercised by the magnet on two or three substances; but these observations, which were unknown to Faraday, had been permitted to remain without extension or examination. Having laid hold of the fact of repulsion, Faraday immediately expanded and multiplied it.
Thus about fifty years ago OErsted, of Copenhagen, discovered the deflection of a magnetic needle by an electric current; and about the same time Thomas Seebeck, of Berlin, discovered thermoelectricity. These great discoveries were soon afterwards turned to account, by Nobili and Melloni, in the construction of an instrument which has vastly augmented our knowledge of radiant heat.
The beautiful experiments of Seebeck and Peltier show the convertibility of heat and electricity; and others by Oersted and myself show the convertibility of electricity and magnetism. But in no case, not even in those of the Gymnotus and Torpedo, is there a pure creation or a production of power without a corresponding exhaustion of something to supply it.
Accumulators of this kind are highly useful as reservoirs of electricity for maintaining the electric light, or working electric motors in tramcars, boats, and other carriages. In the year 1821 Professor Seebeck, of Berlin, discovered a third source of electricity.
In Goethe's diary Schopenhauer's name frequently occurs, and on the 24th November 1813 he wrote to Knebel: "Young Schopenhauer is a remarkable and interesting man.... I find him intellectual, but I am undecided about him as far as other things go." A few days later Goethe wrote to the distinguished scientist, Dr. Seebeck, asking him to read the work.
The thermo-battery, the discovery of Seebeck in 1822, was alluded to as a means of converting heat into electric energy in the most direct manner; but this conversion could not be an entire one, because the second law of thermo-dynamics, which prevented the realization as mechanical force of more than one seventh part of the heat energy produced in combustion under the boiler, applied equally to the thermo-electric battery, in which the heat, conducted from the hot points of juncture to the cold, constituted a formidable loss.
In 1813 Seebeck discovered the polarization of light by tourmaline. That same year Brewster discovered those magnificent bands of colour that surround the axes of biaxal crystals. In 1814 Wollaston discovered the rings of Iceland spar.
Sir John Herschel and Seebeck have shown that there exists, beyond the violet, a faint violet light, or rather a lavender to b, to which gradually becomes colorless; similarly, red light exists beyond the assigned limits of the red ray to a.
Here he found the temperature actually higher than in any part of the visible spectrum. By this important observation, he proved that the sun emitted heat-rays which are entirely unfit for the purposes of vision. The subject was subsequently taken up by Seebeck, Melloni, Müller, and others, and within the last few years it has been found capable of unexpected expansions and applications.
Volta had found that two dissimilar metals in contact will produce a current by chemical action, and Seebeck showed that heat might take the place of chemical action. The direction of the current, indicated by the arrow, is from the bismuth to the antimony across the joint, and from the antimony to the bismuth through the external wire.
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