vivid and conspicuous, but was peculiarly remarkable from its exquisite whiteness. Indeed, there seems no great presumption in comparing its splendour to that of the sun; for I am not sure that the eye would be able to look at a disc of such light, if its diameter were made to subtend half a degree.

"The next series of experiments was the most interesting and decisive of all. Each of the lights above enumerated, viz., the single Argand burner, the seven Argands, and the French lens, were exposed, one at a time, in company with your light, in order to try their relative brilliancy.

« First comparative Experiment.-The single Argand burner was first exposed to this comparative ordeal, and nothing could be more pitiable than the figure it cut. Many of the party could not see the Argand light at all; while others could just detect it away in a corner,' as some one described it. It was also of a dusky orange tinge, while your light was of the most intense whiteness.*

"Second comparative Experiment.-The seven Argand burners were now substituted in place of the single light. All the party could now see both lights, but the superiority was not much less obvious. I really cannot affix a proportion either as to size or brilliancy; but I should not hesitate to say that your light was at least six or eight times as conspicuous; while in brilliancy, or purity, or intensity of light (for I know not precisely what word to use to describe the extreme whiteness), the superiority was even more remarkable. All this which I have been describing was expressed, and appeared to be quite as strongly felt, by the rest of the company, to the number, I should suppose, of five-and-twenty or thirty persons, who were all closely on the watch.

"Third comparative Experiment.-The next comparative trial was between the French lens and your light. The superiority here was equally undeniable, though the difference in the degree of whiteness was not so remarkable. The French

* "To many the rays from the brighter light appeared, when seen with the naked eye, to extend across and envelope the fainter light, though the perpendicular distance between them was twenty-five yards."

light, however, is so nearly similar to that from the seven Argands, that the comparison of each of them with your light gave nearly the same results, and all equally satisfactory on the score of your discovery.

"Final Experiment.-The flashes with which the experiments concluded were very striking, and might, I think, be turned to great account in rendering lighthouses distinct from one another. The revolutions were not effective, and, as I said before, there was no appearance last night of those enormous comets' tails which swept the horizon on the night of the 25th, to the wonder of all who beheld them: neither could there be detected the slightest trace of any shadow from the light thrown towards us; and I suspect none will ever be seen, when the moon, whether the night be clouded or not, is of so great a magnitude.

"Such is the best account I can give of what we witnessed; and I need only add, that there seemed to be amongst the company but one opinion of the immense superiority of your light over all the others brought into comparison with it.—I am, &c. BASIL HALL."

The superior brilliancy of the light being thus established, the only point for farther inquiry was the expense of its production. The result of Mr Drummond's inquiries on this point are set forth in his paper, and are unfavourable to his light. "It may, however, in this, as in every similar instance," he observes, "be expected that, after a little experience, a considerable reduction in the cost would be effected."

"This is a new source of artificial light, differing from every other at present in use, and the materials by which it is produced are among the most abundant products of nature; but never having yet been applied on a great scale to any practical purpose, it has not hitherto been an object to obtain them in a separate state at a small expense. Meanwhile, however, the case in question may perhaps be regarded as one where expense ought not to be a primary object of consideration. On all ordinary occasions, the preference of one mode of illumi

nation to another is a question of convenience, luxury, or economy; but in this it assumes a more important character, for it involves to a great extent the preservation of life and property. The advantage of the light being fully recognised, attention may now be exclusively directed to remove some of those minor obstacles that might render its use in lighthouses objectionable; and I have great pleasure in adding, that the Trinity Corporation are desirous that every facility in their power should be afforded with a view to effect this object, and that a series of preliminary experiments is accordingly to be carried on at their expense."

It was but for a short time that Mr Drummond was free to prosecute such inquiries. He was engaged in them up to the spring of 1831. In a letter to his mother, dated February 22, 1831, he writes: "Truly this same light gives no small trouble.

In

the last paper which I sent to the Commissioners, I stated that the French light equals, if it does not surpass, the best of the lights in our lighthouses in splendour, while it is superior to them in economy and facility of management. This Stevenson either denies, or has hitherto been negligent in ascertaining. The experiments at Inchkeith have been ordered by the Commissioners [of the Northern Lights], with a view to judge of the point themselves, and not trust to Stevenson's opinion. It is a question between the present method and the French light, not between mine and either. Their relative values have been ascertained by the Trinity House and Blackwall experiments, in a way which admits of no doubt. To recommence similar experiments would be mere trifling. There are obstacles in my way of a different kind, relating to the manufacture of the gas, management, &c., which I am now endeavouring to remove. With respect to brilliancy there can be no doubt." By the middle

of the year, however, his political employment commenced; and though he never lost sight of the subject, he was never able again to recur to it. "This abstraction of Mr Drummond's attention," says General Larcom, "at the moment when he was nearest to success, must, so far as the light is concerned, be considered matter of regret with its projector it has dropped; but if it be practicable, ingenuity will, doubtless, sooner or later, be directed to render it available, and the Drummond light may yet cheer the home-bound mariner from the Great Skellig or the Tuskar."*

* For some time the Drummond light has gone out of public notice. The interest and the expectations it excited at one time may be gathered from a question put to Mr Drummond when under examination as a witness before the Select Committee on Lighthouses in April 1834. "The Committee would like very much to have it on their minutes what circumstances gave rise to this very great and important discovery, which is likely to be of such infinite use to the world at large?" In an article in the "Edinburgh Review" for April 1835, reviewing the Report of this Committee, a suggestion of Sir David Brewster's that the Drummond light should be employed as a separate instrument in every lighthouse for occasional use, is considered and adopted. The occasional light was proposed to be used only in hazy weather, when other lights are either altogether obscured, or lose their characteristic appearances. "The general system of illumination by oil or gas lamps and lenses is adequate, in ORDINARY WEATHER, to every want oft he navigator; and nothing could be more irrational than to introduce the lime-ball light into lighthouses as a general mode of illumination-unless it could be done as cheaply, as safely, and as effectually as the present improved system with oil or gas lights. The lime-ball light holds out to us an admirable resource in seasons of occasional danger; but we cannot approve of the idea of making an unnecessary glare upon our coasts, with the inseparable accompaniments of unnecessary expense and unnecessary danger." The inadequacy of the ordinary lights for other than ordinary weather, i.e., for all occasions when their aid is most wanted, is here confessed. On the other hand, that greater expense and danger are inseparable from the use of the Drummond light is assumed, but is

And here a break may be made in this monotony of scientific detail, by quoting an amusing letter, written by Mr Drummond to his mother, describing his visit to the king for the purpose of presenting to him a copy of the paper, read before the Royal Society, on the Trinity House experiments. The letter, which sets Drummond in a new light, tells its own story so fully that no words of introduction to it are necessary, unless, indeed, it may be proper to prefix the postscript: "It takes a long time to tell a story on paper. If I had anticipated such a long yarn,' I am afraid I should not have attempted it. But I hope it will amuse you, and that was my object."

"LONDON, January 24, 1831.

"MY DEAR MOTHER,-I have begun with a sheet as large as your own, but whether I shall fill it as well is another question. The business part of your letter shall be first answered, and the remainder of the sheet devoted to amuse you.

Now, as you sent me a description of the lecture [most probably a lecture delivered in Edinburgh on the Drummond light], I mean to send you a description of another scene which may not gratify you so much, but which, I hope, will nevertheless interest you. Believe me, my dear mother, the chief, perhaps the only

by no means certain. Had Mr Drummond been free for a little longer to follow up the subject, it is not improbable that his ingenuity would have enabled him to overcome these objections, and that ere now his light would have superseded every other for lighthouse purposes. The following recommendation of the Committee on Lighthouses seems not to have been attended to. They say—“Captain Drummond stated to the Committee all the objections to the present use of his light in lighthouses; but your Committee are so strongly impressed with its importance, and with the merits and ability of Captain Drummond, that they recommend that means should be adopted without delay for prosecuting still farther the experiments recommended by him, and under his direction if possible; or, if he cannot superintend them, then under some fit person."