Journal 



OF THE 



NEW-YORK MICROSCOPICAL SOCIETY. 



VoL.1. JANUARY, 1885. No. 1. 



ELECTRICAL ILLUMINATION IN MICROSCOPY: 



EXPERIMENTS AND VIEWS OF DRS. HENRI 



VAN HEURCK AND THEODOR STEIN. 



BY E. A. SCHULTZE. 

 {Read November ']th, 1884.) 



This subject has for some time had the attention of scientific 

 men both in this country and in Europe. Among the first to 

 note the advantages of the electric light in microscopical research, 

 figures Dr. Henri Van Heurck, of Antwerp, a student who ranks 

 as high in Belgium as does Mr. Edison in the United States. 

 His investigation began, about ten years ago, with a trial of the 

 effects of a Galvanic battery on platinum, but the trial yielded 

 no satisfactory results. He was the first to employ the Swan 

 lamp for microscopical illumination, the experiment being made 

 at the Paris Exposition. Shortly afterward, in November, 1881, 

 with a view to greater progress in this work, Mr. Swan endeav- 

 ored to manufacture the smallest possible lamps ; and in the 

 following January he constructed one which required only seven 

 volts, or the power of four Bunsen elements, and sent it to Dr. 

 Van Heurck. The latter carefully tested its usefulness, and he 

 published the results in the Proceedings of the Belgian Society 

 of Microscopists. In March, 1882, a committee of that Society 

 visited him for the purpose of witnessing his methods and 

 measuring their success. Before the end of that year he pub- 

 lished in the Bulletin of the Society an extended article on the 

 adaptability of electrical illumination to the microscope, in 

 which he gives a theoretical explanation of the superiority of 

 the electric light over all others, and much useful information, 

 besides, regarding its practical working. He found that for the 

 resolution of diatoms, as wlU as for all other work requiring ob- 

 jectives of high power, the light furnished by his electric lamp, 



