176 POPULAR SCIENCE MONTHLY. 



academy made for convenience and efficiency are all now embraced in 

 the two classes already named. The king died in 1840. At that time 

 the income of the academy from all sources was a little more than 

 $15,000. It had not increased materially since 1809, and yet out of 

 this small income some money had been saved and invested as capital. 

 The king had preserved the independence of its members save in regard 

 to the censorship exercised over their private writings, and had en- 

 trusted its care to wise advisers. During this reign, advance in knowl- 

 edge, especially in scientific directions, had been very great. The 

 academy had done some excellent work in all the departments of knowl- 

 edge which it represented. In mathematics, worthy of mention are 

 Dirrichlet, Steiner, Weierstrass, Jacobi and Kummer. When only 

 twelve years, Dirrichlet spent his money for books on mathematics. 

 From the Cologne gymnasium he went to Paris to hear La Place, 

 Legendre, Forier and Poisson. He not only could understand Gauss's 

 'arithmetical disquisitions,' but he could make their meaning clear to 

 others. He married Eebecca Mendelssohn Bartholdy in 1832, and 

 after that time till his death his house was an intellectual and social 

 center in Berlin. In the estimation of those who know it best his 

 work was as important as that of Descartes in the use of analysis in 

 geometry. Astronomy made good progress under Encke. His study 

 of the occultation of Venus in 1796 enabled him to determine more ac- 

 curately than had ever been done the parallax of the sun. In physics 

 many names have become famous. Paul Ermann and Seebeck were 

 in the academy before Frederick William III. occupied the throne; 

 Dove, who laid the foundation of the science of modern physics; Pog- 

 gendorf and Magnus came in prior to 1840. Ermann was in the acad- 

 emy from 1806 to 1851, was one of its secretaries from 1810 to 1841 

 and did as much as any one to help forward its development. DuBois 

 Eeymond was accustomed to speak of him as one of the best physicists 

 of his era and as preparing the way for physicists like Magnus, and 

 physiologists like Johannes Miiller. Magnus was trained in chemistry 

 by Berzelius and Gay Lussac, and in his turn trained many of the best 

 modern chemists of Germany. Seebeck, after laboring thirteen years 

 in the academy, withdrew to Jena, living upon his private means and 

 devoting himself wholly to scientific studies. Mitscherlich, the dis- 

 coverer of isomorphism, and Heinrich Eose, the discoverer of niobium, 

 were trained by Berzelius and as analytical chemists have been ranked 

 with their teacher. J. B. Karster, Weiss and G. Eose were eminent as 

 mineralogists, and Leopold von Buch is credited with having laid the 

 foundation for the study of geology and paleontology in Germany. 

 His geological map in twenty-five leaves, published in 1821, had in 

 1843 run through five ^editions. For many years Link was the keeper 

 of the botanic garden in Berlin, and with his own money founded its 

 present magnificent herbarium. Harkell and Kunth were associated 



