22 THE SCIENTIFIC PAPERS OF 



ment will, ifc may be safely affirmed, be used universally for all 

 except local telegraphic communication. 



In the year 1845, when the practical utility of electric telegraphs 

 had been demonstrated in England, several continental govern- 

 ments determined upon their establishment. The Belgian, Austrian, 

 and, a few years later, the Sardinian Government, simply adopted 

 the double-needle telegraph. In France, Messrs. De Foy and 

 Breguets fils, contrived a double step-by-step or dial telegraph on 

 Wheatstone's principle, which enabled them to imitate the same 

 code of signals which had been used for the Semaphore telegraph. 



In Prussia, a royal commission was appointed to consider and 

 advise upon the system to be adopted, of which commission my 

 brother, Werner Siemens, who had been engaged before with 

 kindred subjects, became the most active member. The com- 

 mission was in favour of an underground system, and charged 

 Werner Siemens to institute experiments. About this time gutta- 

 percha had become known in this country, and having been struck 

 with its peculiar plasticity, I forwarded my brother a sample, to 

 see whether he could use it for the purpose he had in view. He 

 soon discovered its remarkable insulating properties, and re- 

 commended an experiment on a large scale, which, having been 

 sanctioned, he completed a line of from four to five English miles 

 (between Berlin and Grossbeeren) successfully in the summer of 

 1847. The machine he designed for covering the copper wire with 

 gutta-percha is nearly identical with the cylinder machine still 

 used for the same purpose. In the spring of 1848 a considerable 

 length of gutta-percha coated copper wire was submerged in the 

 harbour of Kiel for military purposes, but it was found that, owing 

 probably to the impurity of the material, the gutta-percha underwent 

 a gradual change, as though it was penetrated by sea-water, to 

 counteract which Werner Siemens proposed, with apparent effect, 

 to mix a small proportion of sulphur with that substance. In 

 the same and following year more than a thousand miles of gutta- 

 percha coated line wire was laid down underground, and proved 

 successful for several years, when it began to fail, for the most 

 part, in consequence of the impure and adulterated condition of 

 the material then supplied. Although the underground line wire 

 has, for the most part, been superseded again by the suspended wire, 

 I venture to assert that we shall eventually return to it for all 



