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A Dutch seventeenth-century etcher and draughtsman, Reiner Zeeman by name, attracted him. He copied, too, Ducereau and Nicolle. "An etching by the latter of a riverside view through the arch of a bridge is like a link between Meryon and Piranesi," says D.S. MacColl. Meryon also studied under the tuition of a painter named Phelippes.
It was the Dutchman, Zeeman, who first observed a change in the appearance of certain spectral lines as a result of light passing through a magnetic field. This discovery, however, is in two respects typical of modern science. The Zeeman effect consists in the splitting up of certain spectral lines into other lines hence, of a breaking up of a whole into parts.
A sodium flame was placed between the poles of a magnet, and the yellow lines were watched in a spectroscope when the magnet was excited. No change could be detected, and none was found by subsequent investigators until Zeeman, of Leiden, with more powerful instruments made his famous discovery, the twenty-fifth anniversary of which has recently been celebrated.
The great modification brought to a radiation by the Zeeman effect may, besides, combine itself with other phenomena, and alter the light in a still more complicated manner. A pencil of polarized light, as demonstrated by Signori Macaluzo and Corbino, undergoes, in a magnetic field, modifications with regard to absorption and speed of propagation.
This almost direct consequence was perceived by Lorentz, and it led him to the new idea that radiations emitted by a body ought to be modified by the action of a strong electromagnet. An experiment enabled this prevision to be verified. It was made, as is well known, as early as 1896 by Zeeman; and the discovery produced a legitimate sensation.
Apart from the fact that our own way of combining observation and thought guards us against drawing theoretical conclusions from Zeeman's discovery, Rudolf Steiner's indication opens up the prospect of achieving quite practical results, opposite in character to those of the Zeeman effect.
What he actually saw, however, as was proved at the Mount Wilson Observatory in 1908, was the effect of a powerful magnetic field on radiation, now known as the Zeeman effect. The 150-foot tower telescope of the Mount Wilson Observatory. An image of the sun about 16 inches in diameter is formed in the laboratory at the base of the tower.
Such whirling masses of hot vapors, inferred from Sir Joseph Thomson's results to contain electrically charged particles, should give rise to a magnetic field. This hypothesis at once suggested that the double lines observed by Young might really represent the Zeeman effect. The test was made, and all the characteristic phenomena of radiation in a magnetic field were found.
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