LA YING DEEP-SEA CABLES. 443 



APPENDIX I. 



DESCRIPTIONS OF THE ATLANTIC CABLES OF 

 1858 AND 1865. 



(Distance from Ireland to Newfoundland, 1,670 Nautical Miles.) 



Old Atlantic Cable, 1858. 



Conductor. A copper strand, consisting of seven 

 wires (six laid round one), and weighing 107 Ibs. 

 per nautical mile. 



Insulator. Gvtta percha laid on in three 

 coverings, and weighing 261 Ibs. per knot. 



External Protection. Eighteen strands of char- 

 coal iron wire, each strand composed of seven wires 

 (six laid round one), laid spirally round the core, 

 which latter was previously padded with a serving 

 of hemp saturated with a tar mixture. The 

 separate wires were each 22 gauge ; the stand 

 complete was No. 14 gauge. 



Circumference of Finished Cable y 2 inches. 



Weight in Air, 20 cwt. per nautical mile. 



WeigJit in Water, I3'4 cwt. per nautical mile. 



Breaking Strain, 3 tons 5 cwt., or equal to 4-85 

 times the cable's weight in water per mile. Hence 

 the cable would bear its own weight in nearly five 

 miles depth of water, or 2*05 times the 



