506 
Proceedings of the Boyal Society 
Appendix I. 
Descriptions of the Atlantic Cables (^1858 and 1865. 
(Distance from Ireland to Newfoundland, 1670 Nautical Miles.) 
Old Atlantic Cable, 1858. 
Conductor. — A copper strand, consisting of seven wires (six laid 
round one), and weighing 107 lbs. per nautical mile. 
Insulator. — Grutta percha laid on in three coverings, and weigh- 
ing 261 lbs. per knot. 
External Protection. — Eighteen strands of charcoal 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. Id gauge. 
Circumference of Finished Cable, 2 inches. 
Weight in Air, 20 cwt. per nautical mile. 
Weight in Water, 13*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 — 
Deepest Water to be encountered, 2400 fathoms, being less than 
2|- nautical miles. 
Length of Cable Shipped, 2174 nautical miles. 
New Atlantic Cable, 1865. 
Conductor. — Copper strand consisting of seven wires (six laid 
round one), and weighing 300 lbs. per nautical mile, embedded for 
solidity in Chatterton’s compound. Diameter of single wire *048 = 
ordinary 18 gauge. G-auge of strand *144 = ordinary No. 10 gauge. 
Insulation. — Grutta percha, four lajmrs of which are laid on alter- 
nately with, four thin layers of Chatterton’s compound. The weight 
of the entire insulation 400 lbs. per nautical mile. Diameter of 
core *464 of an inch ; circumference of core 1*46 inches. 
External Protection. — Ten solid wires of diameter ’095 (No. 13 
gauge) drawn from Webster and Horsfall’s homogeneous iron, 
each wire surrounded separately with five strands of Manilla yarn, 
saturated with a preservative compound, and the whole laid spirally 
