A. Hasemann, Berlin C. W. A. Hirschmann, Berlin N. 19 



(fig. 2), in the case of a cylindrical surface = r (sin a sin- - j, (fig. 3). 



- The section at the point of contact between a cylinder and a plane, 

 the line A B, (fig. 4), is, on account of the compressibilit}" of the 



material, a curved line The existence of the components 



shows that the fulcrum cannot be in A B. Rotation of the cylinder 



Fig. 4. Fig. 5. 



is, therefore, necessarily accompanied by a sliding movement along 

 A B and produces therefore friction. The forces, acting in the line 

 of contact of two similar cylindrical surfaces have, on the contrary, 

 no horizontal components, because, as fig. 5 shows, that path is a 

 straight line. A B represents therefore the fulcrum and rotation 

 takes place without friction. 



No. 2765. 



W. A. Hirschmann, Berlin, N. 



1415 Johannisstrasse. 

 Manufacturer of Electro-Therapeutical Apparatus. 



Established 1862. 



1. Stationary Electro - Medical and Electrolytical Cabinet, 



^consisting of: 



Galvanometer for absolute measurements, resistance box, induction 

 coil, pole reverser, cell numberer, commutator, influence machine and 

 all accessories for Franklinization. 



2. Stationary Cabinet for electro-medical and electrolytical 

 purposes, illumination and galvanic cautery, arranged for connection 

 with an electric light installation of 110 volts. 



The apparatus may be used simultaneously for illumination and 

 galvanic cautery, or for illumination and electrolysis etc., and is fitted 

 with all necessary appliances for connection with electric light installations. 



3. Stationary Electro-Medical and Electrolytical Cabinet, 

 consisting of: 



Galvanometer for absolute current measurements, pole reverser, 

 commutator, induction coil and cell numberer. 



4. Stationary Cabinet for electro -medical and electrolytical 

 purposes, similar to No. 3, simple construction. 



