LIGHTHOUSES OF THE FUTURE
By SIR WILLIAM THOMSON, LL.D., F.R.S.

A ship sailing from the west, bound for Liverpool, shapes her course for Cape Clear. For four days the weather has been cloudy, and no "sights" of sun or stars have been obtained. From the "dead reckoning," the latitude is estimated at 51°  15", and the longitude 11°  18", at four P.M. on the 10th of September, 1873; Cape Clear, 68 miles distant E. by S.½.S.  The ship is hove toand the deep sea-lead cast, and no bottom is found. Again at seven in the evening the lead is cast -- no bottom at 90° fathoms. An hour later the captain, a cautious man, and thorough navigator, heaves to, and casts the lead again. This time he finds bottom at 75 fathoms. Knowing that the Irish coast is well lighted, be stands on his course of E.S.E. at an estimated rate of 8½  knots through the water, and looks out anxiously for the Fastnet. It is flood tide, equinoctial springs, and he has a knot or a knot and a half with him eastward, he believes. Three-quarters of an hour later a light, faintly visible, is made out on the port bow, and almost instantly disappears. After three or four minutes it is seen again, and in the course of the next ten minutes it is seen five or six times each time appearing and disappearing rapidly.  This is decidedly the Fastnet, seen just half an hour earlier than was expected from the soundings, and the captain is well pleased. (See chart of Cape Clear, Dingle Bay.) Heavy showers come on, and the light is only seen two or three times again until about ten o'clock, when in intervals between the showers it is seen several times on the port beam, shining out, and becoming eclipsed rapidly, as is the way with a revolving light. The captain alters his course by a point and a half to F. half S., and expects to see the Old Head of Kinsale light half an hour after midnight. At a quarter past ten his ship is ashore on the south end of Vickillane Island, on the north side of the entrance to Dingle Bay. The dead reckoning had given about 40 miles south and 24 miles east of the true position at four in the afternoon, a by no means large error on a five days' run without sights. A careful navigator would, of course, be quite prepared for such an error in the dead reckoning; but in this case the captain, after having felt his way cautiously by soundings, was thrown off his guard by making out a revolving light just in the position in which he expected to see the Fastnet. If he had seen a flashing light or a fixed light, he would have known it was the Calf or the Skelligs, and altered his course accordingly; but having made out a revolving light, be did exactly as almost every man would have done in such circumstances. On behalf of the existing system, it may be urged that the Tearaght light which he had taken for the Fastnet revolves in a minute and a half, whereas the Fastnet revolves in two minutes. This defence is utterly invalid. It is scarcely possible for any one, counting time to himself on a gusty, showery night at sea, to distinguish a one-and-a-half minute from a two-minute revolving light. It is never convenient, and it is often impossible, to find the period of a light by noting on a chronometer the times of its appearances and disappearances.

Take another case. A coaster from the Clyde, bound south, takes refuge from a southerly gale in Belfast Lough. After he has been three days at rest in the snug anchorage of Whitehouse Roads, the wind moderates, and draws more from the west-ward about nightfall. Not wishing to lose more time, he gets under weigh to go to sea the same night, half an hour before high water. He reads in the sailing directions, "The Copeland light in line with Grey Point "ESE. ¼ F., clears the foul ground on this "shore" (the south shore of the Lough, west of Grey Point). His position (A) in the anchorage was such, that Grey Point shut out the Copeland light from his view; so as soon as his anchor is up, he sails N.F. till he sees what he believes to be the Copeland light, well open to the north of Grey Point. (See chart of Belfast Lough) His cargo is of pig iron, and he does not trust his compass, so he does not notice, and, in fact he could not discover that the light bore F. by 5.45. instead of F.S.E. ¼ E., when it first became visible open of Grey Point. He steers for the light, knowing that the ebb tide to the northward will keep him clear of the dangers of the Copeland channel, and he is soon ashore a mile and a half west of Grey Point, at the top of high water. He had really never seen the Copeland light, but had taken for it the clear fixed light of an ironclad, (S) anchored in six fathoms water two miles east of Grey Point. Passing from imaginary cases, take the real one of the steamer "Cambria," lost on Inistrahul on the 19th of October, 1870. Passengers and crew to the number of 183 perished. One man only, John McGartland, escaped to tell the sad tale. Two days after the event, the keeper of the lighthouse on Inistrahul reports that he and his wife "on Wednesday, about midnight, heard what appeared to be cries of distress. They opened the lighthouse door, and every gust of wind brought with it shrieks as if from men and women in despair. They also observed a light in the direction of the Tor rocks outside of Inistrahul. This light flickered for a very few minutes, and then disappeared, and soon all was silent. It was a wild, stormy night, and to have ventured out would have been certain destruction." On the testimony of the lighthouse keeper as to the direction in which the light was seen, it has been inferred that the Cambria foundered not on Inistrahul, but on the Tor rocks. "The fishermen in the locality say that on Wednesday night there was a strong five-knot tide running east, and the gale also blew from the west."