282 SEC. 10. ELECTRICITY. 



The current passes from the movable conductor into an annular cup, con- 

 centric with the axis of the motion and filled with a conducting liquid. 



All the conductors are made of aluminium so as to lessen their weight as 

 much as possible. 



The apparatus may be used for a great number of experiments ; it is spe- 

 cially adapted for the following demonstrations: 



1. Parallel currents in the same direction attract one another, and those in 



contrary directions repel one another. 



2. Angular currents in the same direction attract one another, and those in 



contrary directions repel one another. 



3. The attraction and repulsion of the same current are equal. 



4. A sinuous current acts like a rectilinear current of the same general 



direction and having the same extremities. 



5. A closed current takes a direction perpendicular to the magnetic meridian. 



6. A solenoid has the essential properties of a magnet. 



7. The elements of the same current repel one another. 



The mutual action of magnets and currents is demonstrated by means 

 of the same apparatus, by replacing one of the currents by one or more 

 magnets. 



1398a. General Table, by Ampere, with apparatus used by 

 him in the discovery of the action of currents. 



College of France, Paris. 



1399. Apparatus for demonstrating the action of Me- 

 tallic Discs in movement upon a metallic wire used as a voltaic 

 conductor. Professor Daniel Colladon, Geneva. 



Experiment performed on 4th September 1826, in presence of the Paris 

 Academy of Sciences, by Messrs. Ampere and Colladon. 



Bulletin de Sciences Mathematiques, by De Ferussac, vol. 6, p. 212. 



1400. Model of a Circular Railway, for showing the 

 rotation of a metal ball upon it by the passage of an electric 

 current. George Gore, F.R.S. 



(See Philosophical Magazine, Feb. 1859.) 



1401. Electro-Spherical Motive Power, with double 



motion. G. Trouve, Paris. 



VII. APPARATUS FOR REGULATING THE 

 STRENGTH OF ELECTRIC CURRENTS. 



1402. Wheatstone's Rheostat, or changeable resistance, for 

 quickly adding or subtracting a low resistance. 



Elliott Brothers. 



1403. Voltastat and Voltameter combined. 



Frederick Guthrie, F.E.S. 



Air-tight through the stopper of a cylindrical vessel containing dilute sul- 

 phuric acid pap. (1.) Two platinum wires coated -with glass. (2.) A long 

 and wide tube open at both ends, the lower end reaching to the bottom of the 

 cylinder. (3.) A tube opening freely beneath the stopper and above by a 

 very fine capillary opening. The platinum wires are enlarged into platinum 

 plates, which are triangles with their apices downwards, and further apart 



