﻿1874.] L. Scliweiidler — 0)i the general T\eory of Duplex TeJerfrapln/. 5 



The ingenious methods were never tried with that zeal and perse- 

 verance which is necessary to carry a new invention successfully through. 

 They were indiscriminately rejected after a few trials made without method 

 or consideration, and the real conditions of success or failure were never 

 examined or pointed out. Thus naturally a prejudice was created against 

 Duplex Telegraphy, and it was fostered by a host of school literature up to 

 the latest time as pointed out before. Further, not a single physicist or 

 electrician investigated the question with a view to ascertaining what 

 quantitative eifect the variable condition of lines has on duplex working 

 as compared with single working. 



If such an investigation had been made, it would have been found tliat 

 -the technical obstructions in the way were by no means so formidable as 

 had been represented, and that the electrical condition of the lines, as well 

 as the perfection of the instruments, and the professional education of the 

 staff, would have fully admitted of the successful introduction of Duplex 

 Telegraphy at least 10, if not 20, years ago. 



It is true indeed that the suggestion of using condensers for balancing 

 the charge and discharge of a line has only been made very lately, being 

 one of Stearns' happy ideas ; but this should have been no reason against 

 introducing the system on short and overworked lines, where the charge and 

 discharge is imperceptible. If only one Telegraph administration had 

 shewn the perfect practicability of the system on a short line, the cloud of 

 prejudice would have been dissipated, and suggestions for overcoming the 

 charge and discharge on long overland lines and submarine cables would 

 have been readily enough given, and thereby large capitals saved. 



To sura up, therefore, we have the following causes which acted 

 persistently against the introduction of Duplex Telegraphy. 



Firstly, the invention was in advance of the age. 



Secondly, the Telegraph profession, young as it is, is far more conser- 

 vative than is good for the advance of Telegraphy, and on the whole 

 Telegraph administrations and staffs have by no means that professional 

 education which is required to conduct practical experiments with a clear 

 understanding, and thence deduce rational conclusions. Thus prejudice was 

 created, which was increased from year to year by authors of school litera- 

 ture writing most discouragingly of the subject. 



Thirdly, unfortunately, during all that time no physicist found it worth 

 his while to investigate the duplex methods with a view to ascertain quan- 

 titatively what can be expected of them, and how they actually compare, 

 with respect to safety, with single working. 



Fourthly, duplex working itself could not progress, because it was 

 neither tried nor investigated, and hence no suggestions for overcoming the 

 difticulty of charge and discharge were called for. 



