In addition to the above, there have been laid across American rivers, since 1854, 95 lines, in lengths of from 120 feet to two miles, and comprising from 120 feet to 6 miles of insulated wire each,—making an aggregate of 250 miles of subaqueous wire in operation on this continent, and a total of 6,979 miles of cable, and 11,127 miles of submarine wire in operation in all parts of the world.
Table II.
Submarine Telegraph Cables which have been successful for some Time, but are not now working.
| No. | Date when laid. | From | To | Number of conducting wires. | Length of cable in statute miles. | Length insulated wire in statute miles. | Maximum depth of water in fathoms. | Weight in tons per statute mile. | Length of time the cables have worked. |
| 1 | 1850 | Dover | Calais | 1 | 25 | 25 | 30 | .. | 1 day. |
| 2 | 1853 | England (Three Cables) | Holland | 1 | 360 | 360 | 30 | 2.00 | 5 yrs. |
| 3 | 1854 | Holyhead | Howth | 1 | 75 | 75 | 70 | 2.00 | 5 " |
| 4 | 1854 | Nantucket | Cape Cod | 1 | 25 | 25 | 16 | .. | .... |
| 5 | 1855 | Varna | Balaklava | 1 | 355 | 355 | 300 | 0.10 | 9 mos. |
| 6 | 1855 | Balaklava | Eupatoria | 1 | 1 | 1 | .. | .. | 9 " |
| 7 | 1856 | Martha's Vineyard | Cape Cod | 1 | 5 | 5 | 15 | .. | 2 wks. |
| 8 | 1856 | Newfoundland | Cape Breton | 1 | 85 | 85 | 360 | 2.50 | 9 yrs. |
| 9 | 1857 | Sardinia | Bona | 4 | 150 | 600 | 1,500 | .. | 3 " |
| 10 | 1857 | Varna | Constantinople | 1 | 170 | 170 | .. | 0.75 | 5 " |
| 11 | 1857 | Cape Cod | Naushon | 1 | 1 | .. | .. | .. | 2 " |
| 12 | 1857 | Martha's Vineyard | Nantucket | 1 | 30 | 30 | 16 | .. | 4 " |
| 13 | 1857 | Sardinia | Corfu | 1 | 700 | 700 | 1,000 | 0.90 | 1 " |
| 14 | 1858 | England | Channel Islands | 1 | 102 | 102 | 60 | 2.50 | 3 " |
| 15 | 1858 | Ireland(Atlantic) | Newfoundland | 1 | 2,500 | 2,500 | 2,400 | 1.00 | 23 ds. |
| 16 | 1859 | Singapore | Batavia | 1 | 630 | 630 | 20 | 0.04 | 2 yrs. |
| 17 | 1859 | Suez (Red Sea & India) | Kurrachee | 1 | 3,500 | 3,500 | 1,910 | 0.94 | 6 mos. |
| 18 | 1859 | Spain | Africa (Centa) | 1 | 25 | 25 | .. | 1.00 | 1 yr. |
| 19 | 1859 | England | Isle of Man | 1 | 36 | 36 | 30 | 2.50 | 3 yrs. |
| 20 | 1859 | South Australia | Tasmania | 1 | 100 | 100 | 60 | 2.00 | 1 yr. |
| 21 | 1859 | Liverpool | Holyhead | 2 | 25 | 50 | 14 | 3.10 | 1 " |
| 22 | 1859 | Syra | Candia | 1 | 150 | 150 | .. | 0.89 | 3 yrs. |
| 23 | 1860 | Across the Mersey | .. | 1 | 3 | 3 | .. | .. | 1 yr. |
| _____ | _____ | ||||||||
| 9,053 | 9,527 |
Table III.
Submarine Telegraph Cables Which Are Total Failures.
| No. | Date when laid. | From | To | Number of conducting wires. | Length of cable in statute miles. | Length of insulated wire in statute miles. | Maximum depth of water in fathoms. | Weight in tons per statute mile. |
| 1 | 1852 | Holyhead | Howth | 1 | 75 | 75 | 70 | 0.45 |
| 2 | 1852 | Portpatrick | Donaghadee | 2 | 17 | 34 | 160 | .. |
| 3 | 1852 | Portpatrick | Donaghadee | 5 | 15 | 75 | 160 | 4.80 |
| 4 | 1854 | Holyhead | Howth | 1 | 65 | 65 | 70 | 2.00 |
| 5 | 1855 | Sardinia | Africa | 6 | 50 | 300 | 800 | 8.00 |
| 6 | 1855 | Cape Ray | Cape North | 3 | 30 | 90 | 360 | .. |
| 7 | 1855 | Sardinia | Africa | 3 | 160 | 480 | 1,500 | 3.70 |
| 8 | 1857 | Ireland (Lost in laying) | Newfoundland | 1 | 300 | 300 | 2,400 | .. |
| 9 | 1859 | Candia | Alexandria | 1 | 150 | 150 | 1,600 | 0.89 |
| 10 | 1865 | Ireland | Newfoundland | 1 | 1,300 | 1,300 | 2,400 | 1.75 |
It will be seen from the above list of failures, that the great extension and success of submarine cables has been attained through many great failure,—among the most prominent being the old and new Atlantic, the Red Sea and India, (which was laid in five sections, that worked from six to nine months each, but was never in working order from end to end,) the Singapore and Batavia, and Sardinia and Corfu. None of these cable, with the exception of the new Atlantic, were tested under water after manufacture, and every one of them was covered with a sheathing of light iron wire, weighing in the aggregate only about fifteen hundred pounds per mile.
These two peculiarities are sufficient to account for every failure which has occurred, with the exception of the new Atlantic. No electrical test will show the presence of flaws in the insulating cover of a wire, unless water, or some other conductor, enters the flaws and establishes an electrical connection between the outside and inside of the cable. All cables now manufactured are tested under water before being laid.