.V/A' \\-lI.l.IAM S/KMENS, F.K.S. 109 



rendered tin- use of a very low battery power a matter of great 

 practical importance. The terra "working speed" was often 

 understood in a different manner from that in which he regarded 

 ir. He considered it to mean the speed obtained when working 

 ordinarily, and fully spelling all the words with the recording 

 instrument. By using abbreviations, and by dispensing with 

 translations at intermediate stations, the speed might be increased. 

 Since the Malta and Alexandria cable had been laid, further 

 improvements in telegraphic instruments had been made by the 

 firm to which he belonged, by means of which the required con- 

 ditions were fulfilled, and a higher rate of working was attained. 



A< regarded the Gutta Percha Company, he wished it to be 

 distinctly understood, that it was not in disparagement of their 

 work that he had stated in the paper, that it was found necessary 

 to reduce the standard from 100 millions of units to 90 millions of 

 units. On the contrary, he thought the company had made extra- 

 ordinary progress in the manufacture of gutta percha during the 

 last few years. In fact, the gutta percha in the core of the Malta 

 and Alexandria cable, taken specifically, insulated, material for 

 material, several times better than that in any other cable previously 

 manufactured ; but, to give a faithful record of what had happened, 

 it was incumbent upon him to mention the fact that the standard 

 had been lowered. It had been stated that neither gutta percha 

 nor india rubber were soluble in water, and that they were capable 

 of being made insoluble by covering them with a preparation of 

 copal and collodiuui. He would refer to the diagram, Plate 7, 

 showing the results of experiments extending over an interval of 

 300 days ; and from that it would be seen, that in sea water, indui 

 rubber, and especially bottle india rubber, lost considerably in 

 weight after 100 days' immersion. At first a slimy skin formed 

 upon the surface, which by degrees increased, and, although the 

 quantity of india rubber actually dissolved was small, yet that fact 

 of its dissolution had to be borne in mind in the construction of 

 submarine telegraph cables. However slow the action might be, it 

 would ultimately prove destructive to the cable, as the places which 

 would suffer most would be those where the insulation was already 

 feeble from injury, or from partial defect in the coating. Before 

 venturing to propose the outer covering of copper referred to in 

 the paper, he had collected all the data upon the subject which he 



