333 SEC. 10. ELECTRICITY. 



Made by the Geneva Association for the construction of Scientific 

 Instruments. 



De la Rive Collection. The property of Messrs. Soret, 

 Perrot, Sf Sarasin, Geneva. 



A large sphere, made of wood, represents the earth. Two iron cylinders 

 represent the two extremities of the terrestrial magnetic axis. They pene- 

 trate into two globes filled with rarefied air, which simulate the higher 

 regions of the polar atmosphere. The electric discharge, which takes place 

 in this rarefied air, following rays all around a point situated in the prolonga- 

 tion of the terrestrial axis, turns about this point, and so turns in a different 

 direction at either pole, when the two cylinders are charged by means of a 

 horse-shoe electro -magnet, in accordance with the observations upon the 

 rotation of the rays of the Aurora Borealis. See " Archives des Sciences 

 physiques et naturelles," 1862, vol. 14, p. 121. Philosophical Magazine, 4th 

 series, vol. 23, p. 346. 



1750. Metallic Plates, Watch Case, used byA.de la Rive 

 in his first experiments in galvanic gilding. 



Lucien de la Rive, Geneva. 



1750a. Telegraphic Instruments. 



Messrs. Siemens Brothers. 



1. A B C telegraph instrument with finger keys (under glass cover to 

 show working parts). 



A magneto-electric instrument not requiring battery ; used for house,, 

 private, and railway telegraphs. 



2. A similar instrument hi wooden case. 



3. A B C telegraph instrument with handle movement, in round case, not 

 requiring battery ; used for house, private, and railway telegraphs. 



4. A similar instrument in square case. 



5. Standard ink recording telegraph instrument with self-starting and self- 

 stopping arrangement ; for terminal stations. 



6. A similar instrument arranged for translation. 



7. Portable telegraph sounder for military purposes (Major Malcolme pat- 

 tern), non-polarized. 



8. Polarized circular relay with double contact. 



9. Bi-polarized circular relay with double contact. 



10. Portable condenser of ^ microfarad capacity, with 2 terminals and 

 short circuit peg. 



11. Sub-divided condenser of 1,2, 2,5,10, 10, microfarad capacity, with 

 4 spring pegs and one short circuit peg. 



12. Sub-divided condenser of 10, 10, microfarad capacity, with 3 terminals 

 and short circuit pegs. 



13. Sub-divided condenser of , ^, 1, 2, microfarad capacity, with spring 

 pegs and short circuit peg. 



14. Sliding rheostat of 10,000 units resistance. 



15. Sliding rheostat of 8,400 units resistance. 



16. Sliding rheostat of 1,300 units resistance. 



17. Resistance coil of 1,000 ohms. 



18. Portable resistance bridge for electrical testing, with 3 pairs of propor- 

 tional coils, viz., 10, 100, 1,000, 10, 100, 1,000, and a set of 16 coils of the 

 aggregate resistance of 10,000 units. All the coils are of platinum-silver 

 alloy. The apparatus also includes battery key, galvanometer key, and 

 reversing commutator. 



