443

Total

.......

26,763

£51,123 It must be evident that so large an amount levied on the commercial shipping for the public general lights, besides the amount levied for local or harbour lights, must form a considerable portion of their expenses.

Returns from some of the harbours of the amount of local light dues will be found in the Appendix, but there has been difficulty in obtaining returns, and no correct account has been made up of the total amount of these dues in the harbours.

It may be observed, that in the lists of lights, general and local, published officially from the Hydrographer's-office, and made up to 1844, there are only 238 lights of various kinds.

ECONOMY IN THE MAINTENANCE OF

LIGHTHOUSES.

i

For many years the French have used for their lights colza or rapeseed oil, which costs about 38. 8d. a gallon, whilst in England the best sperm oil is used, which costs from 58. to 88. per gallon; the price of oil alone must make a considerable difference in the expense of maintenance. Mr. Wilkins, of Long Acre, a Lighthouse Lamp Manufacturer, has invented a lamp of peculiar construction, in which he burns rapeseed oil; and he has offered to supply and maintain a lighthouse of 15 burners, providing lamps, oil, and everything necessary to maintain the light, exclusive of wages and furniture for the lighthouse, at the rate of 1517, 98, for twelve months. He says that

half the expense of the oil for lights would be saved by using the rapeseed oil. But Mr. Halpin (of the Ballast Board, Dublin,) states that about one-sixth more of rapeseed oil than sperm oil is consumed in the same time, and that in his opinion the saving will not be so much. Mr. Wilkins states, in proof of his opinion, that he has, for some years past, supplied rapeseed oil to several lights abroad, the light at Dover, the Tees navigation lights, the light at the Nore, and at other places, where the rapeseed oil has given a brilliant light, and is spoken of confidently as likely to afford a great saving.

Your Committee consider, that after such experience, the public lights in this country may safely be tried with that oil, with the view of economy. By reference to the Appendix for an example, it appears that the whole ordinary expense of the Flamborough light was 7017, in the year 1843; and of that sum 3037. was for oil. The Dungeness light cost 5321. for ordinary maintenance, and the oil cost 2297. of that sum. But the comparison of aggregate expense, when applied to any other charges than the mere expense of oil and lighting stores, is fallacious, because establishment of keepers and other expenses must be the same, whether the number of burners be more or less; and Mr. Herbert states that there is no certain standard of comparison applicable to any other charges there. At Pakefield, for example, one burner is kept, but the servants to attend it, viz. a principal and assistant, are as many as at Beachy Head, where there are 30 burners.

In the United States, a Committee of Congress has reported on their lighthouse establishment, and have stated that their expenditure for their 272 lights in 1842 was only 85,7241. Whilst the amount of 5081. was the average charge in 1832 for each of the land lights in the United Kingdom, the average expense in the United States was only 1907. sterling; but, as has been already stated, entire reliance cannot be placed on this comparison until the whole of the circumstances are more fully ascertained.

It is proper to observe, that that Committee in the United States made experiments as to the power of illumination, by lard, by sperm oil, and by gas from resin, and the result would warrant the belief that a great saving might be effected in our lighthouses by the use of lard, oil, gas from resin, or of other substitutes for sperm oil; and the result of these experiments is stated to have been,

resin gas sperm oil

And burnt for the whole night, giving the same degree of light.

se

I

Sir, I have again read in your columns other specimens of the intelligence of your correspondent, Pressure not Puff." had reason to suppose, from the nature of my letter, and the severe castigation Lin flicted upon him, and which he has evidently so keenly felt, that I should have induced him to attach his name, for the future, to his able lucubrations; so that I, as well as others, might know what dependence may by placed upon his facts. Discretion, however, it seems; he deems to be the better part of valour; and, consequently, I fear we shall never learn, with certainty, who he is. I have been highly amused with his two last letters-they are evident specimens of the wonderful ignorance a man may display, who unites a natural obtusity of intellect to the impotence of age; and thus negatives the advantages which a long life and experi ence are supposed to confermeda

The letter I wrote has had one good end, although it has failed in bringing him out; for it has enabled me to guess with tolerable certainty, as to who he may be; and I have little doubts of the correctness of my impression, when I believe him to be the same person who, when the Parliamentary

return of the performances of the several steamers of Her Majesty's navy were moved for in the year 1841, had the audacity to write a letter to the officer ordered by the Admiralty to furnish that important document, to intreat him to make a false report to favour his work.

The animus he has shown, while commenting upon my letters, as well as in reflecting upon the Board of Admiralty, will be sufficiently explained, when I state, that to their lordships directly, and to me indirectly, he is indebted for, to him, the lamentable falling off of Government contracts he receives, the Board, in their more recent distributions, having preferred “Real Pressure and no Puff." I need hardly say, that I look to him to fulfil his promise, and as there is no alteration in tone on my part, to pluck up sufficient courage to furnish me with his name.Juolor 90w JUC. HoSEASON," fed itaoup Jewet8i 3dCommander R. N.

We have no idea to whom Captain Hoseason alludes in this letter, as being the supposed writer of the letters signed ** Pressure not Puff" but we think it right to state at once, that none of the circumstances by which he imagines he has identified the

party, can possibly have the smallest appli-" cation to the real author. He never has been a Government contractor, and is as little open to the imputation of "impotence of age," as Captain Hoseason himself. We regret the manner of Captain Hoseason's present letter, but cannot deny him the opportunity of vindicating himself in his own way. Perhaps there has been

445

72.5

Silica JohmAlumina Ferre *** 9°0 Protoxide Manganese. 13.2 Magnesia gard• » Lime

་་

2.0

1:58

With respect to the call made on "P. N. P‚”, to give his real name, we may repeat what we have said (in substance) some hundreds of times before, that as long as a writer's facts and arguments do not rest on his personal authority, it matters nothing whether he writes in his own name, or anonymously; indeed it is better for the cause of truth, that he should adopt the latter course.En. M. M.]

4 1

ON A SPECIMEN OF ARTIFICIAL ASBESTOS. BY F. PENNY, PH. D., PROFESSOR OF CHEMISTRY IN THE ANDERSONIAN UNIVERSITY.

FOR a specimen of this substance, I am indebted to Mr. William

very accurate of Monk

land; and, for a analysis of it, to his son, Mr. Francis Murray."

It was found in a Blast Furnace, imbedded in the mass of matter which had collected at the bottom of the furnace in the course of two years and a half, and which is technically called the hearth; it was in a cavity, about eight inches below the level on which the liquid metal rested, and was interspersed with distinct and beautiful crystals of titanium...! 67.tie mit

4

In all its general characters, this substance corresponds with asbestos. It is colourless, inodorous, and tasteless-and occurs in small masses, composed of extremely minute filaments or fibres, cohering longitudinally together These fibres are very easily detached from each other and are flexible, though not so much so as the common asbestos. They have a silky lustre, and are unattacked by sulphuric, nitric, or muriatic acid. They remain unchanged in the flame of a spirit lamp, and are difficultly fusible even with the blowpipe.

A

A preliminary examination having been made to ascertain the ingredients contained in the substance, ten grains of the longest and cleanest of the fibres were selected for analysis. This was the largest quantity that could be obtained free from adventitious matter. The process adopted was the one usually recommended for the analysis of insoluble siliceous minerals. The following are the results per cent e pr

of asbestos, we remark, that the artificial specimen contains about ten per cent. more silica, and that magnesia, of which there is twenty-five per cent. in natural asbestos, is replaced by the protoxide of manganese. Now, it is well known that the protoxide of manganese is isomorphous with magnesia, and hence this replacement of the one by the other, is at once explained. I apprehend the substitution of manganese for magnesia will be found much more frequent in the mineral kingdom when minerals are submitted to improved methods of analysis. The occurrence of asbestos in an iron furnace affords a beautiful proof of the igneous origin of this substance.-Proc. Phil. Soc. of Glasgow.

ON ARTIFICIAL ULTRAMARINE." BY JOHN STENHOUSE, PH. D.TOS and Till within the last twelve or or fifteen years the only source of this beautiful pigment was the rare mineral, lapis lazuli. The price of the finest ultramarine was then so high as five guineas the ounce. Since the mode of making it artificially has been discovered, however, its price has fallen to a few shillings the ounce. Artificial ultramarine is now manufactured to a very considerable extent on the Continent, but as far as I can learn, none has as yet been made in Great Britain. The chief French manu. factories of ultramarine are situated in Paris; and the two largest ones in Germany are those of Meissen in Saxony, and of Nuremberg in Franconia. Three kinds of ultramarine... occur in commerce, the blue, the green, and the yellow. The two first only are true ultramarines, that is, sulphur com pounds; the yellow is merely chromate of baryta. Joshus our you -21981l_angl

Both native and artificial ultramarine have been examined very carefully by several eminent chemists, who, however, have been uns able to throw much slight upon their true nature. Chemists have undoubtedly ascer tained that ultramarine, always consists of silica,alumina, soda, sulphur, and a little oxide of iron; but no two specimens, either of the native or artificial ultramarine, contain these ingredients in at all similar proportions. In fact the discrepancies between vibido e dxl dt and