JOURNAL 



OP THE 



ASIATIC SOCIETY 



Part II.— PHYSICAL SCIENCE. 

 No. II.— 1875, 



IX. — On the General Theory of Duplex Telegraphy. 

 By Louis Schwendler. 



(Continued from Vol. XLIII, Part II, 1874.) 



In the two preceding investigations* I have given the solution of the 

 first problem for the hriclge method. This solution established the general 

 result of the double balance being the best possible arrangement for the 

 bridge method. In the present paper I shall endeavour to find the solution 

 of t\ie, first problem for the differential method, which in practical impor- 

 tance ranges second to the bridge-method. 



II. Differential method.f 



This arrangement for duplex working is based on the well-known me- 

 thod, of comparing electrical resistances " differential method," and Fig. 2 

 gives the general diagram when this method is applied for duplex working. 



* J. A. S. B., Vol. XLIII, Part II, 1874, pp. 1 and 218 ; Phil. Mag., Vol. 48, 

 1874, p. 117 and Vol. 49, 1875, p. 108 ; Journal Telegraphique, Vol. II, p. 580. 



f The differential method was originally invented, as stated before, by Mr. Frisehen, 

 and Messrs. Siemens and Halske. A particular case of this method was patented by 

 them in England in 1854. 



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