(Continued from page 215.) THERE remains to be considered the distribution of lights on a coast and the positions in which they should be placed.

It will be readily conceived that, important as it is to produce a brilliant light, which may be seen from a long distance by ships at sea, yet that the selection of the positions in which to place such lights is a matter of no less importance, lest, like the "ignis-fatuus," they should but lure the wayfarers of the sea to destruction, instead of guiding them to the haven where they would be.

On a bold open coast with a broad expanse of sea alone stretched out before it, such as the coasts of Spain and Portugal, facing the Western Ocean, this is a comparatively simple operation, and a few powerful lights, on the leading promontories and near the few harbours, suffice for all the exigencies of passing and local trade; and some simple deviations in alternate lights are then enough to prevent any one light being mistaken for another. In the case, however, of a country like our own, with its vast local trade, confined channels, numberless harbours, flat shores, deep inlets, and outlying banks of sand shingle and rocks, and with its rapid, changing, and eddying tides, all making navigation dangerous, and taxing the skill and seamanship and watchfulness of the mariner to the utmost, the coast-lights of such a country must be much more numerous; and from their comparative nearness to each other, and the consequent danger of confusion, the diffiiculty of arranging them is of necessity much increased. If our shores were a " tabula | rasa," without a single coast-light existing, and we had now to establish a perfect system which, like Minerva springing, ready armed, from the head of Jupiter, should at once come into complete existence, the task of adequately lighting our coast without risk of confusion would doubtless be much easier than it now is; but, like our political and social systems, that of our sea-coast lights has been of slowly progressive growth, and as each want has developed itself, it has been met as best it might, each fresh supply being " dovetailed" into the already existing system with as little disturbance as possible.

In perfecting a system of sea-coast lights, then, two leading requirements have to be borne in mind. First, wliat may be termed the duty of the lights themselves, viz., the general guidance of vessels coming within sight of their benignant rays, or the warning them from-the treacherous bank or sunken rock or other danger; and, secondly, the effective performance of that duty by so proclaiming their own identity as to leave no room for doubt in the mind of the wavetost mariner as to the same.

In fulfilling the first of these requirements, the character of the light and of the building containing it has to be decided by the nature of its position or of the duty required of it, as to whether, for instance, it has first to warn the seaman returning from some distant voyage, who for many days or weeks has seen nought but sea and sky, of his approach again to land; or whether, as in the case of our own Eddystone, it has to scare him from the treacherous rock on which itself is raised; or whether, as in the case of our floatinglights, its office is to direct him clear of outlying sands, such as the Goodwin and those which cover the approaches to the Thames and Mersey; or whether, again, it stands on the long, low point of land where it must be raised aloft to be seen above the crests of the very waves themselves; or is placed high up on the towering cliff, already too near to the region of cloud and haze. In each case the speciality of the requirement has to be considered, and the character, both of the light and its dwelling, must be decided thereby.

It is not, then, sufficient merely to place a large number of brilliant lights along the most prominent parts of a line of coast, or wherever else required, but the greatest care must be taken to prevent one light from being mistaken for another. This error has often been the cause of shipwreck and loss of lives, especially on coasts like those of our own iblands, where, from the navigation being intricate, the lights are necessarily placed at comparatively short distances from each other, and where the strength and varied direction of the tidal currents often cause vessels to be carried considerably out of their reckoning.

As an illustration of this danger, no stronger case could be quoted than that of the loss of the fine American clipper ship Pomona, which was wrecked on the Blackwater Bank in the Irish Channel, on the 30th April, 1859, an account of which will be found in the July number of this Journal for that year.

That unfortunate ship, which was only two days from Liverpool on her way to New York, ran on the above dangerous bank, through the floating Blackwater Light being mistaken for the Tuskar, and in twelve hours afterwards she went to pieces, and with her perished no less than 385 of the 444 persons on board her. Another well-known wreck from the same cause was that of the Great Britain, a few years previously, in Dundrum Bay. No doubt hundreds of other fatal shipwrecks have occurred from similar mistakes, but we have thought it worth while to refer to these two well-known and striking cases of recent date, involving the loss of two first-class ships, as indicative of the importance of a judicious selection of site, and of giving all adjacent coast-lights j such a distinctive character as to reduce to a minimum the liability of one being mistaken for another.

The following judicious rules on the subject we extract from the article on Lighthouses in the " Encyclopaedia Britannica" :— " 1. The most prominent points of a line of coast, or those first made on ' over-sea' voyages, should be first lighted; and the most powerful lights should be adapted to them, so that they may be discovered by the mariner as long as possible before his reaching land. 2. So far as is consistent with a due attention to distinction, revolving lights of some description, which are necessarily more powerful than fixed lights, should be employed at the outposts on a line of coast.

3. Lights of precisely identical character and appearance should not, if possible, occur within a less distance than 100 miles of each other on the same line of coast, which is made by over-sea vessels. 4. In all cases, the distinction of colour should never be adopted except from absolute necessity. 5. Fixed lights, and others of less power, may be more readily adopted in narrow seas, because the range of the lights in such situations is generally less than that of open sealights.

6. In narrow seas, also, the distance between lights of the same appearance may often be safely reduced within much lower limits than is desirable for the greater sea-lights. Thus there are many instances in which the distance separating lights of the same character need not exceed 50 miles; and peculiar cases occur in which even a much less separation between similar lights may be sufficient. 7. Lights intended to guard vessels from reefs, shoals, or other dangers, should, in every case where it is practicable, be placed seaward of the danger itself, as it is desirable that seamen should be enabled to make the lights with confidence. 8. The elevation of the lantern above the sea should not, if possible, for sea-lights, exceed 200 feet; and about 150 feet is sufficient, under almost any circumstances, to give the range which is required. Lights placed on high headlands are subject to be frequently wrapped in fog, and are often thereby rendered useless at times when lights on a lower level might be perfectly efficient. But this rule must not, and indeed cannot, be strictly followed, especially on the British coast, where there are so many projecting cliffs, which, while they subject the lights placed on them to occasional obscuration by fog, would also entirely and permanently hide from view lights placed on the lower land adjoining them.

In such cases, all that can be done is carefully to weigh all the circumstances of the locality, and choose that site for the lighthouse which seems to afford the greatest balance of advantage to navigation.

9. The best position for a sea-light ought rarely to be neglected for the sake of the more immediate benefit of some neighbouring port, however important or influential; and the interests of navigation, as well as the true welfare of the port itself, will generally be much better served by placing the sea-light where it ought to be, and adding, on a smaller scale, such subsidiary lights as the channel leading to the entrance of the port may require. 10. It may be held as a general maxim, that the fewer lights that con be employed in the illumination of a coast the better, not only on the scope of economy, but also of real efficiency. Every light needlessly erected may, in certain circumstances, become a source of confusion to the mariner; and, in the event of another light being required in the neighbourhood, it becomes a deduction from the means of distinguishing it from the lights which existed previous to its establishment. By the needless erection of a new lighthouse, therefore, we not only expend public treasure, but waste the means of distinction among the neighbouring lights." The best selection of a site for a lighthouse having been made, there remains to be decided the selection of such description of light as shall be as dissimilar as possible to all those within a long distance of it.

On first thought the most obvious means for effecting dissimilitude would naturally seem to be difference of colour, but in practice it is found that coloured media absorb so large a portion of the light that ved is the only colour available and that chiefly in combination with unColoured lights, except in the case of harbour lights, or those in narrow waters, where it is not required that their rays should be thrown long distances* In combination with bright lights, it however appears to us that red lights might perhaps be advantageously used often if than they as yet are, especially in the case of floating and other outlying lights in the neighbourhood of banks or rocks, when liable to be mistaken for other lights, as in the instance of the Blackwater and Tuskar lights above referred to. Thus if the former had been provided with a red subsidiary or duplicate light, which would have been seen by the Pomona on nearing it, the captain of that unfortunate vessel might have discovered his mistake in time, and instead of boldly running on, as he supposed with the open British Channel before him, he would have hauled off to the S.E. and made the Tuskar Light in due course. The Ballycotton Lighthouse, off the coast of Cork, may be quoted in illustration of the useful application of a subsidiary coloured light. In that instance the lower panes of the light-room are of red glass, and the lower rays of the light made more divergent downwards than usual, so that vessels getting too near the land are at once warned to keep farther from it by the light changing from bright to red.

The greatest distance from which fed • lights are readily visible in clear weather is I 10 miles, and of course proportionally less in thick weather when required to be seen.

i Beyond those distances, therefore, bright lights only are available, and the only mode of distinction is by the use of the revolving ! apparatus, thus producing lights alternately | visible and invisible at varying intervals, from the flashing and intermittent lights designed by Mr. ROBERT STEPHENSON* to those with the longest spaces of time between their visibility and obscuration. Masked or hooded lights, visible only over limited portions of the horizon have also been found useful to aid in the navigation of tortuous or duplicate channels; also a different coloured ray to mark a turn in a channel, and other such variations.

The light-towers should be painted not j only conspicuously to make them readily I visible, varying according to the colour of i the background against which they would be viewed, but, as far as practicable, each should have such a distinctive appearance as to be instantly recognised for the same during daylight, and the appearance of the building by day as well as of the light at night, together with the height of the light above the level of the sea, should be published by the proper authorities; the last-named particular LJ of service by enabling an observer with a sextant to ascertain its distance from him.

The English lights are lit at sunset and extinguished at sunrise; the Scotch are lit at darkening and put out at dawn, by which I a considerable saving is made.

I The public lights of all countries are under j the strictest provision and most careful management, every pains being taken to make them efficient.

The British lights are under the general superintendence of the Trinity House in London.

In Scotland the Commissioners of Northern Lighthouses are the acting body, and were incorporated by the Act S8th Geo. III., c. 58.

I In Ireland the Ballast Board of Dublin '. acts in all lighthouse matters. (See the ' 23rd Geo. III., c. 19.) Besides these three public bodies, there are very numerous local authorities which deal with local lights* The principal among those are the Liverpool Board, the • Trinity Houses of Newcastle, Hull, &c. The number of these separate bodies is very great; as, for the 402 lighthouses in Great Britain, there are, at least, 174 different authorities to direct them.

The British Colonial lights are chiefly under the control of the Board of Trade.

We extract the following brief sketch of the great Managing Body of the British Lights, from the excellent and valuable work of ALEXANDER G. FINDLAY, Esq., F.R.G.S., entitled " A Description and List of the Lighthouses of the World " :—* " The ancient Corporation of the Trinity House of Deptford S trend has had, as is well known, the charge of the British Lighthouse System. This is one of the very few institutions which dates from a mediaeval period, and has well preserved its importance and useful character, through all changes, to the present day. That it has done so, the recent Report of the Royal Commission, 1861, will testify.

" The Trinity Corporation, which has developed our English system, under the advice and assist- ance of the most eminent engineers and philo- sophers of all periods, existed in the reign of Henry VII.. as a respectable Company of Mariners in the College at Deptford, having authority by Charter to prosecute persons who destroyed sea-marks, &c.; and Henry VIII., in the sixth year of his reign, May 20, I5H, formed them into a perpetual Corporation, by the style and title of the 'Master, Wardens, and Assistants of the Guild or Fraternity of the most glorious and undivided Trinity, and of St. Clement, in the parish of Deptford Strond, in the county of Kent-' "This Charter was confirmed and altered by Edward VI., Queen Mary, Elizabeth, and James I.

The Charter of James I. settled this constitution of the Corporation, and such it continues. The Charter was dissolved in 1647, but was renewed by Charles If. on the Restoration, and the disposal of the funds was settled partly for charitable purposes. The Charter was surrendered to Charles II., and renewed by his successor in 1685; and the charitable uses of the funds of the Corporation were again settled. These funds were derived from various charges, such as pilotage, lastage, loadmanage, ballastage, &c.

" The interest which the Trinity Corporation represented having, by the extension of commerce, grown into great magnitude, the Government interfered and altered some of their privileges at different periods, especially in 1854, when the Board of Trade partook of the supervision." In concluding our remarks on this highly interesting and important subject, we desire to acknowledge our indebtedness to the above-named work of Mr. FINDLAY, and to a lecture delivered by him at the United Service Institution, as also to the Article on Lighthouses in the Encyclopaedia Britannica, by ALLEN STEPHENSON, Esq.

* Vide also Jfo. 30 of the Life-toot Journal, page 96, for a mure detailed account of the Corporation.

The Messrs. A. & C. BLACK, the wellknown publishers, at Edinburgh, have also courteously placed at our disposal many of the blocks of the illustrations on this subject contained in their national and great work, the Ervyclopcedia Britannica, as did also Mr. FINDLAY, those in his work, of which we have -availed ourselves, and beg to acknowledge the same, with thanks..