No. 63414. 



Selenium cells. Thermo-electricity. 



1061 



63 411. 1 : 4. 



63 412. 1 : 4. 



63408,63409. 1:5. 



63 410. 1 : 7. 



63 414. 1 : 4. 



63,407. Selenium Cell, cylindrical, in evacuated glass tube with ebonite mount and terminals, ' s. a. 

 Figure 3.15.0 



63,408. Flat Selenium Cell, maximum sensitivity, in metal casing with slide, Figure, without 

 stand; resistance, unilluminated, say, 100,000 ohms 



4. 0.0 



63.409. Stand for above, Figure 0. 5. 



63.410. Apparatus for Shewing the Sensitivity of Selenium to Light, Figure, consisting of: 



1 Selenium Cell, 1 polarised Eelay of variable sensitivity, 2 Dry Cells, 1 electric Bell, 



2 Switches: all mounted together on one polished mahogany stand 6. 0. 



In addition to the two dry cells supplied with the apparatus, which are used for working the 

 bell, a 15 20 volt battery is necessary for the Selenium Cell. When the box of the Selenium Cell is 

 opened in bright light, the bell rings, and ceases when the box is closed. 



Section 12: Thermo-electricity. Miscellanea. 



63.411. Thermo-electric Apparatus after Seebeck, Figure, consisting of a copper stirrup 

 soldered on a bismuth rod, on stand, with a magnetic needle (M. P., 9 th Edn., Ill, 

 Fig. 812; W. u. E. phys. Prakt., 4 th Edn., Fig. 326) 



63.412. Thermo-electric Rectangle, Figure, of antimony and bismuth, on stand, with one 

 magnetic needle 



63.413. Rod-shaped Thermocouple, of antimony and bismuth, with terminals soldered on 



63.414. Thermocouple after Pouillet, Figure, on adjustable stand (M. P., 9 th Edn., Ill, 

 Fig. 816) 



To the ends of a bismuth rod, provided with rectangular arms, copper wires are soldered, which 

 lead to two insulated terminals fastened on the apparatus. The form of the thermocouple permits 

 of the two junctions being immersed in liquids of different temperatures. 



s. d. 

 0.16.0 



0. 16. 



0. 8.0 



1. 0.0 





Cl. 3092, 3093, 



5106, 1955, 3094. 



