No. 63 156. 



Wehnelt Valve Tubes. Vacuum Tube Illumination. Theory oJ Electrons. 



1025 



63 141. 1 : 4. 



63 148. 1 : 5. 



Vacuum Tube Illumination after Mac Farlane Moore. 



63.146. Vacuum Vibrator, Figure, with holder, magnet coil, and connecting terminals 

 (Elektrotechn. Ztschr. 1896, p. 637) 2. 14. 



A Wagner hammer interrupter vibrating in an evacuated glass tube produces such clear inter- 

 ruptions that the self-induction currents induced in the magnet coil are sufficient to excite vacuum 

 tubes. 



63.147. Vacuum Vibrator alone 1.2.0 



63.148. Electrodeless Tube, Figure, 0.5 m long 0. 6. 



Section 9: Electron Theory and Radioactivity. 



Apparatusfor School Experiments on theTheory of Electrons, 



after Prof. G. Mahler. 



(cf. Ztschr. f. d. phys. u. chem. U., 22, 1909, p. 98.) 

 63,149. Elder Pith Ball on 3 m long silk fibre 





63.150. Hollow Polished Metal Sphere, 100 mm diameter, on insulating stand 



60,176. 2 Leaf Electroscopes Each 0. 10. 



63.151. Small Wood Board with 2 terminals for stretching glow wires 



Glass Rods, Ebonite Rods, see p. 797; Influence Machines, p. 819; Electric Needles, p. 798 

 of this price list. 



63.152. Leyden Jar, 16 cm high, with hollow ball 100 mm diameter 



63.153. Ebonite Disc 200 mm diameter, coated one side with tinfoil 



63.154. Cardboard Disc with hole 6 mm diameter 



63.155. - - idem, with a number of concentric holes 



63.156. Electroscopic Powder with pulverising apparatus 



62,731. Apparatus for showing that the Air is Ionised by Rontgen Rays, cf. p. 986 . . . 



63,046. Vacuum Tube with stratified light 



60,012. 2 Bar Magnets for above Each 0. 2. 6 



Tubes for Deflecting Cathode Rays: see p. 1019. 



s. d. 



Cl. 3570, 2958, 

 3571,2959. 



0. 0.6 



0.18.0 



1. 0.0 

 0. 4.0 



0.14.0 

 0. 3.0 

 0. 0.3 

 0. 0.4 

 0.10.0 

 2. 0.0 

 0.10.0 

 0. 5.0 



65 



