ll'ILL/AM SIEMENS, F.R.S. 7 1 



tender coating >f highly insulating material. The necessity for 

 ;i iiK'tallic sheathing is however not entirely avoided, in order to 

 afford protection against abrasion and against marine animals ; 

 and this sheathing is proposed to consist of very thin brass or 

 iron wire wound on in the form of a tight lapping while the 

 cement is still soft, so as to be imbedded completely in it. The 

 cable is then drawn through a hot die, which causes the super- 

 fluous cement to cover the wires completely and to preserve them 

 from rusting. 



A cable so prepared combines the qualities essential for crossing 

 deep and broad oceans. Its specific gravity will not exceed 1*5, 

 which experience has proved to be the most desirable weight for 

 submersion, and its tensile strength is such that it will support 15 

 miles of its own length in sea water, instead of only 3 miles, which 

 is the length an ordinary iron-sheathed cable will support. The 

 sheathing of this cable will not be acted upon by sea water, and 

 will retain its full strength therefore in case it should have to be 

 taken up for repairs : it will not be liable to form kinks, which 

 are fraught with danger to the insulation. The chief advantage 

 however is supposed to reside in the insulating coating, which 

 consisting of a succession of perfect tubes of the most highly 

 insulating and tenacious material known, unaltered by heat or 

 solvents and thoroughly protected against external injury, offers 

 the greatest chances for permanent efficiency that could well be 

 realised. For shore ends this cable should receive an additional 

 external covering of strong wires to resist the effects of anchors 

 and violent abrasion ; and these wires in their turn should be 

 covered with saturated fibre to render them durable. The expe- 

 rience with long submarine cables has hitherto been anything but 

 satisfactory ; but there is in the writer's opinion no reason to 

 prevent their being made very permanent and valuable property, 

 if only the expedience now gained is turned to good account. 



Mr. SIEMENS exhibited the machine in action, covering pieces of 

 wire with india-rubber, showing that the joint made by rolling 

 the two fresh-cut edges together under a heavy pressure was so 

 strong that the india-rubber covering would tear at any other 

 part as readily as at the joint. He showed also a number of 

 specimens of the different descriptions of telegraph cable now in 



