The best test taken by Mr. Saunders, 1·30 a.m., Greenwich time, July 25, after the Cable had been cut down to 78·5 miles, gave-- Resistance, shore end disconnected, 2,600 units. “ “ to earth, 312 “ Let _a_ and _b_ be the lengths of Cable-conductor, having resistances equal to the first and second of these numbers; _l_ the length of Cable, and D the distance of the fault. The ordinary formula gives _____________________________________ D=_b_--√(_a_-_b_)(_l_-_b_) Hence, _l_ being 78·5, and _a_ and _b_ being calculated from the observed copper-resistance of the conductor in the after-tank, and various assumed temperatures of the sea, we should have, were the measurements perfect, results as follows:-- +---------------------------------------+----------------------------------+ |Copper resistance of Cable | Distances of the fault calculated| |in after tank, per nautical mile, | accordingly from end in ship, | |observed 4.44 units at 61° temperature.| when cut at 78.5 miles of | | | cable from shore end. | +---------------------------------------+----------------------------------+ |Hence 4·42 units at 59° temperature | 6·7 miles. | | 4·37 “ 53° “ | 10·1 “ | | 4·25 “ 40° “ | 22·0 “ | | 4·02 “ 35° “ | 27·2 “ | +---------------------------------------+----------------------------------+ This would give 22 miles for the most probable distance of the fault, as 40° is the most probable mean temperature of the first submerged length of 75 miles. The true distance proved to be very nearly 3 miles. The discrepance is owing partly of course to want of absolute accuracy in the measurements, but probably more to the variation of the resistance of the fault during the interval between the two measurements. Iron chains were lashed firmly to the Cable at the stern, and secured to the wire rope carried round outside the ship to the picking-up apparatus at the bows. As the paying-out stopped, a strain came on the Cable, which was down in 400 fathoms of water, and it needed nice management to keep the ship steady, as she had no steerage way. The Cable, having been shackled and secured, was severed at 8·50 a.m., and flew with its shackling into the sea, plump astern. The stoppers which held the wire rope were released, and the rope was payed-out rapidly as the Cable sunk, in order that the ship’s head might be brought round, if possible, so as to take the Cable in over the bows in a straight line with its course.