Background
Willem Henri Julius was born on August 4, 1860, in Zutphen, Netherlands. He was the son of Willem Julius and Maria Margareta Dumont.
University of Utrecht, Utrecht, Netherlands
Julius attended school in Gouda, and entered the University of Utrecht in 1879.
1908
In 1908 Julius was named the Knight of the Order of the Dutch Lion.
1908
In 1908 Julius was named the Knight of the Order of the Dutch Lion.
University of Utrecht, Utrecht, Netherlands
Julius attended school in Gouda, and entered the University of Utrecht in 1879.
Albert Einstein
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1888
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1908
Willem Henri Julius was born on August 4, 1860, in Zutphen, Netherlands. He was the son of Willem Julius and Maria Margareta Dumont.
Julius attended school in Gouda, and entered the University of Utrecht in 1879. He received his Doctor of Science degree under Buys Ballot on February 10, 1908.
Julius became professor of physics at the University of Amsterdam in 1890 and at the University of Utrecht in 1896. Among his friends were Einstein, Ehrenfest, Zeeman, Eykman, and Einthoven.
Julius studied the infrared radiation of flames with a radiometer he had constructed. In order to avoid tremors he mounted this instrument in such a way that its center of gravity was supported, a technique known as the Julius suspension. His observation of the solar eclipse of 1901 was the turning point in Julius’ activity; from then on he devoted all of his work to solar physics. August Schmidt had stressed the effects of refraction in the solar gaseous sphere; Julius modified this conception and gave more consideration to the refraction in irregular inhomogeneities and the anomalous refraction of rays having wavelengths quite near to the wavelength of an absorption line.
He explained solar prominences as regions with strong inhomogeneities, where the light of the sun is refracted toward us. The darkness of sunspots was explained by regular refraction. In these conceptions the importance of refraction was vastly exaggerated. Later, however, Julius extended his argument, stating that the rays of a Fraunhofer line would also show anomalous scattering, which would explain the darkness inside the line. This view was later developed independently by Unsold, and even today anomalous scattering is assumed to be the mechanism by which strong solar resonance lines are formed.
During the eclipses of 1905 and 1912 Julius applied a new method for determining the distribution of brightness over the sun’s disk by recording the variation of the total intensity during the partial phases.
Willem Henri Julius wend down in history as a noted physicist. He is best remembered for his work on solar physics, where he modified the conception of August Schmidt and also explained solar prominences and darkness of sunspots. He was also able to determine the distribution of brightness over the sun’s disk.
In 1908 he was named the Knight of the Order of the Dutch Lion.
Julius became a member of the Royal Dutch Academy of Sciences in 1897, and a member of the Hollandsche Maatschappij der Wetenschappen in 1899.
A modest man, Julius lived well and in the traditional manner, showing full devotion to both science and the arts.
On December 23, 1890, Julius married Betsij Mathilde Frederique Einthoven, the daughter of Jacob Einthoven. The couple had a son and two daughters.
