u Skin '''-effect in Electrical Oscillators. 



19 



before one of them failed. Veins appeared in the gold-leaf 

 encircling one platinum cap. On replacing this sphere by a 

 new one only three or four readings were secured before the 

 other sphere of the first pair failed in the same way. This 

 was removed and a new one put in its place, and with the pair 

 thus formed the readings in Table VII were obtained. 



Table VII. 

 Spheres ] cm8 in Diameter. 



Distance of 





Detector position ; and scale reading 



in mm. 





















from 

 Detector. 



I 



11 



III 



IV 



Mean. 



cms. 



I 2 



1 2 



1 



2 



1 



2 











1. i Solid. 













50 



97 



117 



120 



80 



133 



78 



98 



95 



102-3 



100 



81 



90 



88 



104 



78 



100 



66 



72 



84-9 



200 



55 



57 



52 



43 



47 



40 



39 



45 



473 



300 



34 



34 



37 



35 



38 



35 



29 



27 



33-6 



500 



13 



14 



10 



10 



12 



10 



10 



9 



11-0 



600 



9 



11 



8 



7 



6 



8 



6 



7 



7'8 



700 



7 



4 



6 



5 



5 



3 



5 



8 



5-4 









2. Shell. 













50 



110 



92 



113 107 



136 



115 



120 



85 



109-5 



100 



10] 



85 



73 89 



76 



80 



93 



89 



85'8 



200 



45 



45 



49 44 



._ 





.. 



... 



45-8 



300 



30 



34 



32 



34 



.. 



31 









32*2 



500 



15 



12 















13-5 



600 



7 



10 















8-5 



700 



5 



6 















5'5 



If curves be drawn with the mean readings of Tables V, VI 

 and VII as ordinates and the distances from the oscillator as 

 abscissae, the curve for a shell will be found to practically coin- 

 cide with that for the solid sphere of the same diameter. The 

 experiments, therefore, indicate that, both in the case of the 

 cylindrical and of the spherical doublets, the excessively thin 

 gold-leaf shells were quite as efficient as the solid metal bodies. 



This investigation was made in the Jefferson Physical Labo- 

 ratory, Harvard University ; and while under especial obligation 

 to Professor Trowbridge for bis never-failing consideration and 

 encouragement, I would express my gratitude to every mem- 

 ber of his staff for innumerable kindnesses. 



Jefferson Physical Laboratory, Harvard University. 



