84 Scientific Intelligence, 



brother possessed his full share of the family genius, in which 

 ingenuity and persistency were equal factors, and he spent many 

 years abroad in special study of Optics from its mechanical side 

 as well as general astronomy. He was the discoverer of fourteen 

 double stars and was a member of the eclipse expedition to Spain 

 in 1870 and to Wyoming in 1878. He is best known as the dis- 

 coverer of the Companion to Sirius, which he found Jan. 31, 1862, 

 while testing the 18-inch glass just then finished by the firm for 

 the Dearborn Observatory. For this he received the Lalande 

 prize from the Academy of Sciences of France. A medal of 

 honor was given the firm by the Russian Government for the 30- 

 inch refractive of the Royal Observatory at Pulkova. 



The untimely death some years since of his son Alvan, the only 

 male descendant of the family, destroyed the hope which the 

 scientific world shared with the father that the work of the firm 

 might be carried on by the strain which originated it, and Mr. 

 Clark proceeded systematically to preserve the results of his 

 experience, by means of instruction to skilled workmen, especially 

 to Mr. Carl Lundin, his associate for twenty-five years and his 

 natural successor. 



It is impossible to separate the work of the three members of the 

 firm. It is best characterized by the remark that almost without 

 exception the construction of lenses of the first class has been for 

 over thirty years wholly in their hands. Their work came to a fit- 

 ting and not improbably an inevitable conclusion when Mr. Clark 

 delivered to the Yerkes Observatory a few weeks since its 40-inch 

 objective. Mechanical difficulties which good judges thought in- 

 superable beyond 30 inches have been overcome up to 40 inches, 

 and Mr. Clark was already contemplating a still larger lens, but it 

 may well be that the rigidity of glass will fail under the strain of 

 greater weight. The last test of the Yerkes lens before it was 

 shipped from Cambridge indicated a change of definition in dif- 

 ferent positions in its cell. If this be true, a limit, this time un- 

 surmountable, has been well nigh reached ; in view of this it 

 will be eminently proper to say that the firm of Alvan Clark and 

 Sons has written a chapter in Astronomy to which it will be as 

 impossible to add a line as to subtract one. w. b. 



Carl Remigius Fresenius, Professor of Chemistry in the 

 Agricultural Institute at Wiesbaden, died in that city on the 11th 

 of June. He was born in Frankfort a. M. on the 28th of Decem- 

 ber, 1818. In his early life he studied pharmacy and it was while 

 a pharmacist's assistant in Frankfort that his first chemical work 

 was done. In 1845 he removed to Wiesbaden, became the 

 director of the renowned chemical laboratory there, and developed 

 that remarkable ability which finally made him the leading 

 authority in Europe on analytical chemistry. His handbooks of 

 chemical analysis, now known and used all over the world, were 

 published, the qualitative part in 1841 and the quantitative part 

 in 1846. The " Zeitschrift iiir analytische Chemie " was founded 

 by him in 1862 and at once became the center of analytical inves- 

 tigations. For some years he had relinquished his share in the 

 more active management of the laboratory to his son, who will 

 doubtless succeed him. 



