BERLIN-FRANKFORT TELEGRAPH LINE. 89 



of my acceptance my command from the war-office 

 would be transferred to the Ministry of Commerce. 

 Although a position under assessor Nottebohm was not 

 particularly agreeable to me. I nevertheless accepted the 

 call, since it set me free from the present monotonous 

 military life in the little fort, and gave me an oppor- 

 tunity of bringing my proposals into practical execution 

 on a large scale. 



In Berlin I found Halske already busily engaged 

 in work for the line about to be constructed. It had 

 been determined to lay the line altogether underground, 

 as it was feared that above-ground wires would be 

 destroyed in that time of great political excitement. 

 The wires, insulated by a coating of gutta-percha, were 

 to be laid without external protection in a trench a 

 foot and a half deep in the railway embankment. 

 My proposed protection of the communications by 

 means of envelopes of iron wires, iron tubes, or clay 

 channels was not approved on account of the great 

 expense. A contract had already been signed with 

 the Berlin india-rubber factory of Fonrobert & Pruckner 

 for the further construction of subterranean wires. 

 This was the same factory to which I had transferred 

 my model for the covering of copper wires with gutta- 

 percha, and which had already manufactured the ex- 

 perimental line from Berlin to Grossbeeren with a 

 press made according to that model. I had to confine 

 myself to providing for the best possible insulation 

 of the wires. Considerable difficulties stood in the 

 way however inasmuch as. owing to the sudden great 



