As the prevention of shipwreck is of equal importance with the saving of life after the wreck has taken place, it becomes the duty of the Life-Boat Journal, from time to time, to give notice to the mariner of any newly- discovered or little-known rock or danger that may happen to be brought before the Institution in the course of its inquiries into the cases of shipwreck, and the causes of its frequency on our coasts; and we may thus lend our humble aid to assist the Hydrographer and the Trinity Board in making known the changes in sands, and other dangers, which they may have occasion to give - notice of to the public. And we are the more called upon to do so from the liberal aid and support, which, both by counsel and by funds, the Institution has always received from the Elder Brethren of the Trinity House, and from the am pie supply of charts of the coast which, through the kind offices of Sir FRANCIS BEAUFORT, have been placed at its disposal by the Admiralty.

Now that the Atlantic is weekly crossed by steamers, the Fastnet Rock, which lies right in the track, at about 5 miles south- west of Cape Clear, the extreme point of Ireland, will become a well-known land- fall, or point of departure. It is a wedge- shaped mass of schist and killas rock, ex- tending 120 yards in a north-east direction, rising 103 feet above low water, and present- ing its precipitous face, or the base of the wedge, to the south-west, and thus receives the full stroke of the Atlantic wave. On this rock, the Ballast Board of Dublin have recently, and very properly, erected a light- tower, the lantern of which is 155 feet above the sea, and it is expected that the light from Cape Clear will be transferred to this spot, as soon as the stability of the tower has been established.

But the special danger to which we desire to call the* mariners' attention is a sunken rock, having only a depth of 11 feet over it at low water, lying about two cables' lengths, or 400 yards, E.N.E. by compass of the Fastnet. This rock has been known since the year 1832, when Lieutenant HOWE, E.N., examined and reported upon it; but its position would seem to have been for- gotten until the recent examination of it by Lieutenant CHURCH, E.N., Admiralty Surveyor on the south-west coast of Ireland. So great is the sea on the west and south-west coast of Ireland in heavy gales, or long- continued broken weather, that it washed away last winter some of the workmen's wooden houses, lashed with chains on the summit of the Fastnet, at an elevation of 100 feet; and in the " draw " of the sea in heavy gales, the sunken rock to the north- east has been seen exposed in the hollow of the waves.

It has been reported by the workmen erecting the lighthouse, that the great ocean steamers were in the habit of passing dangerously close to the Fastnet, probably to gratify the curiosity of the passengers with a view of the building. They stated that one huge steamer passed so close on the north side that they were in agony for her safety, expecting every moment to see her knocked to pieces on the sunken rock in question ; they shouted to her in vain ; her deck crowded with passengers. She appeared to the workmen to pass actually over the position of the danger: had she touched, not a creature would have been saved. It is hard to say how many missing vessels, from remote periods, have been demolished on this outlying and dangerous rock, or on the Fastnet itself, among the many of which it is recorded in our wreck- register, " Sailed, but not since heard of." We trust that every master or mate of a vessel that may chance to read this notice will immediately mark the spot in question on his -chart with a large black cross, to denote a sunken rock, and will take care, under any circumstances, to give the Fastnet a berth of at least half a mile.

There is the more occasion for this warning, as this track is daily becoming more frequented. In the early months of the year, March, April, and May, and not infrequently in the autumn, in September and October, but chiefly in the spring, long- continued easterly winds prevail with great tenacity, blowing hard at times from east to south-east: this year they blew almost uninterruptedly for two months. The home- ward-bound trade, as is well known, have great difficulty in getting into port after a long tedious voyage, and may run short of water and provisions. In former.times, the great majority of these vessels were to be encountered knocking about the approach to the English channel; but since rapid postal and personal communication by steam and rail have been established between Ireland and England, an immense number of the homeward-bound, for all parts, are too glad to be able to fetch Cork, Crookhaven, and the fine anchorage of Bearhaven; and many get congregated in those harbours.

The mighty growth of the Liverpool and Clyde trade has added, and is daily adding, to the number of vessels that fetch in about Cape Clear, and in long-continued easterly winds they may be seen straggling to make the south-west Irish land on the starboard tack. Even vessels bound up the English channel, after a long voyage, and run short, are but too glad to fetch a port; and the first that can be reached is often Bantry Bay, Crookhaven, or Cork.

On the 18th April, last year, the winds from east to south-east first ceased, after a continuance, with more or less force, for two months, and many vessels suffered much from privation. It is true that Government sends steamers to afford relief, but it is chiefly to the chops of the English channel; whereas, in the line of bearing of south-west and W.S.W. from Cape Clear and Fastnet, pursued from thence out to the edge of soundings, and traversed backward and for- ward, a number of vessels wanting relief would be encountered.