Page:Popular Science Monthly Volume 71.djvu/290

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284
POPULAR SCIENCE MONTHLY
Hermann Helmholtz at the Age of Twenty-seven. From a daguerreotype taken in 1848, a year after the publication of the paper on the conservation of energy.

consequently welcomed a call to the chair of physics in Berlin. Later he organized and became the first president of the "Reichsanstalt," a national laboratory of physics and technology. During these years, he made his great contributions to thermodynamics and electromagnetism, and with his pupils, Hertz, Lenard and others, gave to mathematical physics its dominant position among the sciences. All the while Helmholtz gave continually public addresses and popular lectures, and was engaged in commissions of all kinds. The range and quantity of his work are as remarkable as its epoch-making character.

LINNEAN CELEBRATIONS IN SWEDEN

At the beginning of the eighteenth century the military power of Sweden, so long a leading force in European politics, had been crushed, the people