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THE SCIENTIFIC PAPERS OF 



only a remote chance of arriving at satisfactory results in this 

 respect. 



The author considers it important to notice some other experi- 

 ments, at different temperatures, on the insulation and inductive 

 capacities of wires coated with india rubber, and with gutta percha 

 combined, as compared with those coated with gutta percha, or with 

 pure india rubber alone. The lengths experimented upon varied 

 from 600 yards to 2,500 yards, and consisted of 



1st. Wire covered by common gutta percha. 



2nd. Ditto by two layers of special gntta percha alone. 



3rd. Ditto by one coat of india rubber and two of gutta percha. 



4th. Ditto by one coat of india rubber and one of gutta percha. 



ftth. Ditto by two coats of india rubber and one of gutta percha. 



6th. Ditto by pure india rubber. 



India rubber, both as the better insulator and the more absorb- 

 ing material, should be applied nearest to the core. 



The observations, ranging over temperatures between 50 Fahr. 

 and 85 Fahr., are recorded in the columns of the following 

 Table : 



TABLE I. 



SPECIFIC RESISTANCE OP GUTTA PEKCHA AND INDIA RUBBER, ALONK 

 AND COMBINED, AT DIFFERENT TEMPERATURES. 



