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The last independent discoverer, so far as is yet known, was Mr. Baxendell, of Manchester, who discovered it on May 15.

On May 16 the spectrum was observed by Mr. Huggins and Dr. Miller, and those extraordinary phenomena noticed which are known to all astro

nomers.

Greenwich: July 6, 1866.

I am, Sir, yours faithfully,

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W. T. LYNN. P.S.-July 19. This morning I have received No. 1597 of the Astronomische Nachrichten,' in which another independent discovery of (T) Coronæ is announced from America. Being made at Washington on the night of May 12th, corresponding to the morning of May 13th in Europe, it ranks second or next to Mr. Bermingham's in order of priority. The discoverer was Mr. Fargubar, as the name is printed in the Ast. Nach.; it should probably be Farquhar, of the Patent Office.

I had overlooked that besides Mr. Chandler, another gentleman in the western hemisphere-Mr. Barker, of London, Canada West-detected the star on May 14.

My list is now, I am pretty confident, complete, unless we hear of earlier discoveries in Asia, which, however, cannot anticipate Mr. Bermingham's by more than an hour or two.

In connection with this subject we present our readers with the following chart of the position of the new star, drawn for us by Mr. Knott:

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CHART FOR THE NEW STAR IN CORONA BOREALIS.

Arg. Zone + 26° No. 2765. (Epoch of diagram, 1866.)

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By GEO. KNOTT, Esq., Woodcroft Observatory, Cuckfield.

SIR JOHN HERSCHEL'S DRAWINGS OF NEBULE.

TO THE EDITOR OF THE ASTRONOMICAL REGISTER. Sir, I have lately made a discovery which, whether it be really such or no, at any rate has not, so far as I am aware, ever been pointed out. All Sir J. Herschel's drawings of Clusters and Nebula are represented as they cannot be seen. The way this has come about appears to be as follows. The sketch is placed on paper in exactly the position which the object has in the (inverting) telescope. This sketch is copied on to the copperplate also exactly as it stands on the paper, and the result is, that when the plate is printed the picture is reversed right and left. The inconvenience of this plan is manifest as concerns observers working with the telescope and seeking to make comparisons between what they see and what Sir John indicates that he saw; but worse than all this, Lord Rosse and, so far as I have noticed, all other celestial draftsmen, adopt the common-sense plan of making their drawings to show exactly as the telescope shows, consequently other sketches placed in juxtaposition with Sir J. Herschel's wholly mystify and delude the reader, indeed, I am free to confess that I have myself thus been taken in. More than once have I sought in vain to reconcile the engraving of the Nebula in Orion, appended to Herschel's Outlines of Astronomy, with the original viewed in an ordinary inverting telescope. Fortunately for me, I only copied into my book a limited number of Herschel and Rosse sketches, but in Guillemin's book Sir John's device leads to a far more serious amount of confusion. I am, Sir, your obedient Servant,

Sydenham :
July 7, 1866.

G. F. CHAMBERS.

13 P. XIX. LYRÆ.

TO THE EDITOR OF THE ASTRONOMICAL REGISTER. Sir,— I turned my telescope, 32 aperture, power 220, last night on 13 P. xix. Lyræ, and readily saw it as a quintuple group-the smallest component estimated not above the 13th magnitude, situated between the two pairs, being nearly on the alignment of A and B. Turning afterwards to the Astronomical Register for this month, I found that Mr. W. E. Jones calls attention to this minute object as a good light test. I fancied it had rather a marked blue colour. It may not unlikely be variable, and therefore have escaped the notice of those who have before examined the group with more powerful instruments.

Teignmouth: July 10, 1866.

I am, Sir yours faithfully,

GEORGE J. WALKER.

BRIEF CORRESPONDENCE.

Speaking of the cluster 11 M. Antinoï, Smyth says that a prominent 8th magnitude star is in the middle, "and two following," and in his engraving, the said two are even much brighter than the central star. I viewed this object on July 19, and found it impossible to reconcile the Admiral's description with what I saw; for the two outlying stars were much fainter than the central one. Can they be variable?

G. F. C.

Don't you think that the Register might be graced with a frontispiece (a photograph, if you please) of the most celebrated astronomers of the past and present of all nations, accompanied with a biographical sketch of their lives, similar to the frontispiece of G. Peabody in the Leisure Hour of July this year? Would it not cause a greater circulation?

J. C.

[We fear that the expense would be far beyond what a publication such as ours could bear, however desirable it might be to follow out J. C.'s suggestion.-ED.]

Allow me to ask for a simple process to grind glass specula, and work out a figure.

C.

NOTES AND GLEANINGS.

THE CONSTITUTION OF METEORITES.-A number of interesting inquiries upon the composition of these curious bodies have been conducted by M. Daubrée. He has endeavoured to produce artificial meteorites, by combining together certain materials. His first experiments were made with ferruginous meteorites, which he divides into three classes (1) native iron alone, (2) iron with globules of peridote, (3) iron associated with silicates, peridote, and pyroxene. All meteorites are covered with a black crystalline crust, formed by the fusion of the exterior layer in the passage of the stone through the atmosphere. All the components of stone are also of an eminently crystallizable nature. It might have been expected, therefore, that, after fusing a meteorite, a crystalline surface would have been obtained on cooling. Nothing of the sort however, happens. When a meteorite is fused, the mass separates into two parts very different from each other; the earthy substances and the metallic part solidify separately. The manner in which these residues crystallize is altogether different, owing probably to the rapidity of cooling. The crystals obtained by the fusion of meteorites resemble the long needles water forms on freezing slowly, while the granular semi-crystalline structure of natural meteorites resembles hoar-frost or snow, formed by the sudden passage of water from the state of vapour to the solid state. M. Daubrée proceeds to point out the analogies, chemical and mineralogical, of meteorites with terrestrial rocks, observing that as yet nothing has been found in those bodies which is not a common constituent of the surface of our globe. He remarks, however, that one essential chemical difference is the state of oxidation of the iron, stating that the protoxide, so common in our basic silicate rocks, is almost entirely wanting in meteoric stone, being apparently replaced by native iron. The masses, therefore, he believes to have been originally identical, but have been modified by different actions.- Comptes Rendus.

THE METEOROLOGICAL COMMISSION.-The Report of the Commission appointed to enquire into the condition of the Meteorological department of the Board of Trade, has just been published, and, though a large folio bluebook, is a most interesting one. The Commissioners show that, while great credit is due to Admiral Fitzroy for being the first to organize a system of weather forewarning, the latter is at present by no means perfect or scientific. They show very fully how it may be made more accurate and reliable. In answer to the question as to how this part of the system may be improved, the Commissioners write :-"The system of Weather Telegraphy and of Foretelling Weather is not in a satisfactory state. It is not carried on by

precise rules, and has not been established by a sufficient induction from facts. The Storm Warnings have, however, been to a certain degree successful, and are highly prized. We think that the Daily Forecasts ought to be discontinued, and that an endeavour should be made to improve the Storm Warnings, to define the principles on which they are issued, and to test those principles by accurate observation. Above all, we think that steps should be taken for establishing a full, constant, and accurate system of observing changes of weather in the British Isles."-Popular Science Review.

OUR SUMMER.-Although we have now reached Midsummer, the following observations, published some time since in the Times by Dr. Hjaltalin, of Iceland, will be read with interest by those who remember the meteorological features of the months of May and June:-"We have had a frightful winter, the mean temperature having been about 5 degrees below the mean of our winters. The thermometer during the last few days has ranged between 12 and 14 degrees of Celsius. This state of things will, no doubt, occasion a most tremendous northern icedrift-the consequence of which you will feel in England and other northern countries. The enormous iceblocks will be drifted into the Atlantic, and, melting there, will be the cause of much rain, hail, and snow, with a considerable lowering of your mean summer temperature."-Popular Science Review.

CAUSES AND CONDITIONS OF RAIN.-M. Renou, the distinguished French meteorologist, has put forward his opinions on the subject of the cause of rain, and although his views do not differ materially from those of other meteorologists, they express a useful summary of the causes which produce rain. Rain depends on the following circumstances:-(1.) Elevation of temperature. (2.) Humidity of the air. (3.) Barometric depression. (4.) Variation of temperature. (5.) General conformation of the earth's surface. But all these conditions may modify each other materially, as follows:(1) Rain increases with the temperature, because hot air dissolves more water than cold air. (2.) The moisture of the air, which attains a maximum at the sea-shore, tends to produce a maximum of rain. This cause being constant, whilst the circumstances which tend to produce rain in the atmosphere being present to the slightest extent, rain is frequent, especially small showers, and storms are rare. (3.) In proportion as the mercury falls, there is more chance of rain being formed. Inversely, in countries with a high barometric pressure, such as those in the 30th degree of latitude possess, there is little prospect of rain. Such regions have a tendency to become deserts. (4.) Variations of temperature and irregularities of climate increase the chances of rain. (5.) Finally, the form of the soil plays an important part in the production of rain. An ascending concave soil receives a maximum of rain when it is exposed to rainy winds.-Comptes Rendus, April 9.

ST. ELMO'S FIRE. A good account of this curious phenomenon has been given by Captain Briggs, of the Steamer Talbot, who observed it on the 7th of March, in the Irish Channel, at about one o'clock in the morning. He gives the subjoined description of his experiences;-"I found," he says, "that the light which appeared large at a distance, was made up of a number of jets, each of which, expanded to the size of half-a-crown, appeared of a beautiful violet colour, and made a slight hissing noise. Placing my hand in contact with one of the jets, a sensible warmth was felt, and three jets attached themselves to as many fingers, but I could observe no smell whatever. The jets were not permanent, but sometimes went out, returning again when the snow was heaviest. This was from one to three a.m. daylight I carefully examined the place, but no discoloration of the paint

At

was to be seen. The stem in this part is wood, and iron plates bolted on each side, and it appears to me that the jets came out between the wood and the iron. The barometer stood at 29.1 in. The ship is an iron one, but I did not observe any alteration or other effect upon the compasses. I have seen the same phenomenon abroad, but never before in these latitudes."

THE NEW VARIABLE STAR IN CORONA.-From communications published in the Astronomische Nachrichten it seems certain that the new star rose to its highest magnitude (on May 12) by a remarkably sudden jump. More than one credible observer declares that on the same evening that the star was descried by Mr. Bermingham, of Tuam, and noted as of the second magnitude, they, earlier in the evening, did not detect it, though they had the constellation of Corona under their notice.

THE HORIZON.--If a person's eye is 5 ft. 4 in. above the level of the sea, his horizon will be three miles distant. If 25 ft. above the water his view will be extended to 6 miles; and if four times that height, to twice that distance. The approximate rule is to multiply the square root of the height in feet by 13, which will give the distance of the visible horizon in miles. Thus at an elevation of 100 ft. multiply its square root 10 by 13, which gives 13 miles as the semi-diameter of the visible horizon. The true horizon, not allowing for refraction, which adds to the distance about its twelfth part, is found by the following simple rule :—

The altitudes being 1 4 9 16 25 36 49 64 81 fathoms, The distances will be 1 2 3 4 5 6 7 8 9 leagues, the numbers in the second line being the square roots of those in the first. T. J. BUCKTON.

If the height of the observer's eye is a given number of feet above the sea, the distance seen in miles will be the square root of the number of feet multiplied by 3. Thus, if the observer's eye is six feet above the sea, the 6×3 distance seen in miles will be the square root of or three miles. This formula, though not quite rigorous, is exact enough for all purposes.

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J. C. M.

The following popular rule for ascertaining the height of a distant object is sufficient for ordinary purposes; it has to be reversed when the height is given and the distance is to be ascertained, as in F. G. W.'s query. Any mathematician could prove its approximation to the truth by referring to the articles "Depression of the Visible Horizon," and "Curvature of the Earth." Two-thirds of the square of the given distance expressed in miles will give the elevation in feet, subtracting an arbitrary allowance for refraction. For example, assume the distance to an object to be three miles; the square of 39; two-thirds of which=6; subtract one-ninth of 6 ft. 8 in.; the height of the object is 5 ft. 4 in. In this example a person's eye 5ft. 4 in. above the sea can see three miles over the ocean on a clear day. Reverse the above operation by having the height given above the sea, and then the distance can be ascertained.

L.

The distance of the visible horizon depends entirely on the height of the eye above the sea, and is a problem easily solved by plane trigonometry. Let h be such a height, and r the semi-diameter of the earth, then h+r= the secant of the arc, the tangent to which is the distance sought. See Hull's Trigonometry, ed. 1858, p. 86.-Notes and Queries. A. A.

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