372 SCIENTIFIC CONGRESS OF CARLSRUHE. 



ture in the German language, by the author of the present article, on 

 the electro-magnets invented by himself and on his researches on 

 magnetic adhesion.* Previous to his labors on this subject, there 

 were but three kinds of electro-magnets known: 



1. The rectilinear ; a straight bar of iron, placed in a coil in com- 

 munication with the pile. 



2. The horse-sJioe, or bifurcated electro-magnet; formed from the 

 above by bending it into the shape which the name indicates. 



3. The tubular electro-magnet of Romershausen. 

 M. Nickles has contrived — 



The trifurcated electromagnet, or that with three poles, having, 

 however, but a single coil, yet exerting considerable attractive force. 



The circular electro-magnet, capable of transmitting a movement of 

 great velocity, since the wheels of transmission which he proposes are 

 not toothed ; their periphery being perfectly polished, they derive their 

 adhesive power from the magnetism developed at their circumference. 



Finally, he has introduced the para-circular electro-magnet, applica- 

 ble in the same circumstances, but possessing properties which differ 

 from those of the preceding ones. 



The time which the order of the day left at the disposal of the author 

 was too limited to enable him to give many details respecting these 

 instruments, which were in operation, moreover, under the eyes of the 

 auditory. The professors of physics regarded them with some interest, 

 not only as furnishing a new chapter in the history of electro-magnets, 

 but as having a bearing, besides, on certain special applications, with 

 a view to which they were constructed, particularly the transmission 

 of movement : thus, in regard to railroads as a means of increasing the 

 adhesion of locomotives, the author had already made a first attempt 

 at their application to an entire train on the route of the city of Lyons, 

 and on a gradient of nearly one centimeter per meter. f The effect 

 realized was about nine per cent. 



His Majesty the Emperor, who, on this first trial, had caused a report 

 to be made to him by a commission of physicists and engineers, has 

 quite recently ordered a renewal of the experiment to be made by the 

 Director of the Bureau of Arts and Trades. 



Electricity constituted the occupation of a part of this session. To 

 the lecture just referred to succeeded another on electric chronoscopes, 

 by M. Hessler, professor of physics at Vienna. The speaker passed in 

 review different electro-magnetic chronoscopes, pointed out defects in 

 all of them, and proposed to remedy these by substituting electro-chem- 

 ical chronoscopes, by means of a current acting on paper impregnated 

 with a solution of ioduret of potassium. This apparatus possesses the 

 great advantage of being able to register the observations automatic- 

 ally. 



After M. Belli, professor in the University of Pavia, had explained 

 the properties of an apparatus capable, as he thinks, of indicating the 

 difference between the two electricities; and M. Helmholtz had given 



* Bulletin de la Societe d'encouragement. May and June, 1853. 

 t Monileur Universel, 9th May, 1858. 



