" Skin "-effect in Electrical Oscillators. 13 



No. 3 and No. 4. Copper i-5 mm and 0*8 mm thick, respectively. 



The mantle was of copper tubing and the hemispherical 



ends were spun and then soldered on. 

 No. 5. Solid electric-light carbon. 

 No. 6. Sheet platinum, over a wooden form. The mantle was 



0-0013 cms thick ; the hemispherical ends, which were sol- 

 dered on, were 0'015 cms thick. 

 No. 7. Sheet silver. Mantle, 0*002 cms ;• ends, 0'014 cms . 

 No. 8. Tin foil, 0*0025 cms thick, on a wooden form. 

 No. 9. Gold leaf laid upon a wooden form. According to 



manufacturer, the leaf was about 1/220,000 inch, or 



0-00001 14 cms , thick. 

 No. 10. Silver leaf laid upon wood. Thickness about 0'00003 cms . 

 Upon cylinders covered with gold leaf copper was deposited 



electrolytically, the thickness of the copper being in No. 



11, No. 12, No. 13, No. 14, No. 15, respectively, 0-0001, 



0-00015, 0-0002, 0-0003, 0'0005 cms . 

 No. 16. Silver deposited chemically on glass blown to the 



proper shape. The thickness, obtained by weighing, was 



approximately 0'000013 cms . 



In order to have the ends between which the sparks were to 

 pass as nearly alike as possible these ends were faced with 

 sheet platinum of a thickness 0*003 cms . By means of a die 

 discs of l cm diameter were punched from the sheet. In the 

 case of cylinders No. 1 to No. 4 these discs, after being given 

 the proper spherical curvature, were soldered directly on the 

 cylinder, after which the surplus solder was removed and the 

 platinum polished by a buffing-wheel. 



In the case of No. 5, copper was first deposited on the end, 

 and a cap with curvature. rather greater than that of the end 

 face was cemented on with shellac. To do this a small piece 

 of shellac was placed on the end and the cap placed in position 

 over it. The shellac was melted by holding a hot wire on the 

 cap, which was then pressed by the finger firmly against the 

 end until the shellac hardened. In this way excellent contact 

 was made all about the circumference of the cap. 



No. 6 had excellent platinum faces already, and No. 7 was 

 left without them. On all the rest caps were fastened as on 

 No. 5, i. e., directly cemented with shellac. 



Later on, some of the caps were secured in place by holding 

 them firmly against the end of the cylinder and then deposit- 

 ing copper on the edge of the cap and on the cylinder where 

 it rested. This certainly insured perfect electrical connection, 

 and is superior to the cementing method, being more durable, 

 but the results obtained were not noticeably better. 



