58 GUTTA-PERCHA INSULATED WIRES. 



orders for more considerable experiments with such 

 wires insulated by gutta-percha, which were begun 

 in the summer of 1846 and continued in 1847. la 

 samples placed on the track of the Anhalt Railway 

 in 1846 the gutta-percha was rolled round the wire. 

 It turned out however that the coil got loosened in 

 course of time. I accordingly constructed a screw- 

 press, by which the heated gutta-percha was cohesively 

 pressed round the copper wire under the application 

 of a high pressure. The conducting wires, coated by 

 the help of a sampler press constructed by Halske, 

 proved to be well insulated and permanently retained 

 their insulation. 



In the summer of 1847 the first long subterranean 



D 



wire from Berlin to Grossbeeren was laid by me with 

 such insulated wires. As it stood the test perfectly 

 the question of the insulation of subterranean wires by 

 the employment of gutta-percha and my press appeared 

 to be now successfully solved. In fact since that time 

 not only the subterranean land-lines but also the sub- 

 marine cable lines almost without exception have been 

 insulated in this manner. 



The commission had under consideration the em- 

 ployment, both of the wires coated with gutta-percha by 

 pressing and also my dial and printing telegraph, in the 

 telegraph -system about to be introduced into Prussia. 



The resolution to devote myself entirely to the 

 development of telegraphy was now fixed. Accordingly, 

 in the autumn of 1847 I induced the mechanician 

 J. Gr. Halske, with whom our common labours had 



