It will thus be seen that October and February are precisely the two months when brilliant auroras are most likely to be seen; and that of these two maxima of the annual cycle October has rather the advantage.

The lightning return, prepared on the same principle, is not uninstructive to be compared against the aurora; for, though both in its aërial altitude and actual numerical returns, lightning may be the very opposite of aurora, yet it exhibits a tendency to a similar double maximum in the course of the year; and not a few of the lightning storms of that second, or winter maximum, are locomotive "meteors," travelling from S. W. to N. E., and having undoubtedly a very wide-spread earth-influence and physical signification. The actual numbers are these :—

I WILL not attempt to describe the wonderfully gorgeous display of aurora which I witnessed on Sunday night, February 4. I merely wish to mention a circumstance connected with it which may have some interest. I was watching for the zodiacal light at about 5.30, and, having perceived faint traces of it, I presently saw some peculiar red clouds a little above it; from their rapid change of form I soon became aware that this was the light of an aurora. From that time, and from that spot, it spread rapidly; a bright white arch extending high overhead from W. to E., while a segment of blue sky stretched low down in the

S E. in the magnetic meridian, the space between being filled with brilliant colours. Shortly after this a radiating point became very striking, not in the zenith, but at one-third the distance from the Pleiades to Capella; and then the folds of gorgeous light-red, white, and faint green, interspersed with dark shading, spread from it, like a canopy, down on all sides except in the N. W. never witnessed or read of such a display in these latitudes. With one of Browning's small star spectroscopes the spectrum consisted of a small portion of brilliant red, then a bright band rather close to it, and then two others beyond; the two latter

I

being rather nearer together than the first and second; that at the more refrangible end being the faintest, and that near the red the strongest. I enclose a sketch showing the spectrum, the slit being wide open.

The maximum display was between 6.45 and 7 P.M; at 7.15 it was fading rapidly. Clouds covered the sky at 7.30, and some smart electric showers fell; still I could see that the display was going on; and at II P.M., in spite of dense clouds, the light was sufficient to enable me to read large print. HENRY COOPER KEY

Stretton Rectory, Hereford, Feb. 6

ON Sunday evening 4th inst., a beautiful display of aurora was observed here (lat. 51° 26' 0" N., long. 0° 20′ 53" W.). My attention was first directed to it at 6h. 4m. (G.M. T.) at which time there was a fiery glow over a considerable portion of the southern sky, much resembling the reflection of a distant conflagration. Shortly after, an almost complete auroral arch, of faint orange red light, similar to that at first observed, was noticed, extending from E., above and partly embracing d, e, and Orionis, to W., its altitude (by estimation) at the centre being about 40°, and its extent something like 120°. For a short time this glow was most intense in S.S. E. at a great altitude, but the display attained its greatest intensity about 6h. 15m., when a number of rays or streamers of whitish blue and orange red light appeared as if radiating from a point near d, a, and Persei. At 6h. 20m. nothing was observed but a widely diffused fiery glow, which must have continued more or less during the whole evening, as it was again observed by me at 8h. 25m. JOHN JAMES HALL

Fulwell, near Twickenham

THERE was a fine display of the above phenomenon here on Sunday night, February 4. At five o'clock a muddy undefined redness made its appearance in the N. E. and W., especially in the former, which continued for some time without any very marked change. Towards half-past six the redness became more concentrated, gradually brightened, and finally became of a most intense brilliancy-indeed, so much so that it fairly baffles description, the landscape and the countenances of those standing near being visibly tinged. Streamers soon began to form, and shoot gradually upwards from the horizon in all directions from N. E. by S. to W., some intensely red, some very white, while others were of a greenish hue. The red and white being very brilliant, were finely intermingled, especially in a N. E. direction, while a muddy green prevailed chiefly in the S., and a reddish tinge in the W. By seven o'clock that rare phenomenon, a corona, was formed overhead, assuming a variety of shapes. The most curious part of the display (as far as my experience goes) was the entire ab. sence up to this time of any streamers or coloured haze in a W.

by N. to N. E. direction, the sky being cloudless, perfectly clear,

and the stars shining with their usual brightness. On the formait in a N. direction, spreading rapidly as it advanced, but did tion of the corona a sheet of fan-shaped sea-green haze shot from not proceed for more than 20°, when it suddenly disappeared. The streamers were remarkably steady throughout and straight, unlike those during the display of November 10 of last year, which were wave-like, rapid, and flickering. By half-past seven the entire sky had assumed a greenish tinge, with a reddish glow in some places, and a few resplendent beams of white light from the E. chiefly. At a quarter to eight red streamers became visible in a N. direction, at a considerable elevation, resting on a greenish haze, itself emanating from a very indistinctly white arch spread across the N. At nine the sky was still tinged, and a streamer here and there visible, but by ten the display was over, as clouds had obscured the heavens. Although the red colours were so intense and deep, the stars could be distinctly seen through them, and when the streamers suddenly changed to white, &c., it was possible to see the time on a watch, though the night under ordinary circumstances would have been dark. A common dipping needle which marked 56° at noon changed to 45° before the aurora became visible. Barometer corrected and reduced, 29 748. Temperature, 37° at the time. Solar radiator during the day, 77°. A few shooting stars darted across the heavens in a south from east direction, mainly during the aurora. A wet night afterwards set in.

A VIEW of the magnificent aurora of Feb. 4 was much interrupted here by great masses of cloud, which frequently drifted over large tracts of the illuminated sky, and towards 8 o'clock collected and descended in a general downpour of rain. Nevertheless enough of it was seen to produce a very striking impression. It began to tinge the southern sky at a considerable altitude so early in the evening that I thought it must have been the reflection of a crimson sunset; nor was I undeceived till I had been to the other side of the house, where I found the western horizon glowing with amber light, in which was no trace of the expected ruddiness. Red continued throughout to be the prevailing hue, chiefly in great diffused masses, but occasionally broken up into filaments and streamers; there (was, however, no absence of sheets and columns of the more usual pale green light. The clouds, chiefly heavy cumuli, assumed a strange aspect; sometimes, when opposite to the crimson illumination, reflecting a dull and sombre red, at others, when projected in front of it and enlightened from the other side by the twilight, or the green aurora, standing out in lurid and ghastly contrast. At one period the northern part of the sky, up to a great altitude, though clear and studded with stars, appeared at first sight almost like a black cloud from its contrast to the greenish white sheet which bordered it abruptly at a considerable height on the west; this again passing into crimson masses in the south, and sending out a whitish stream to meet another from the east, and form, probably, for a few moments, a complete bright ring, somewhat south of the zenith, of which, however, only one half could be seen from the post of observation. The light was so intense that even after it had been a good deal obscured by cloud, a large print might have been read without much difficulty. A miniature spectroscope (one of Browning's) brought out some interesting features. The usual yellowish green auroral line was distinct everywhere, and could be perceived even when the instrument was directed to masses of dense cloud; and as was observed by Birmingham on a former occasion, could be made out in the reflection from any suitable terrestrial object; white paper for example exhibited it very obviously. As shown in the brighter greenish patches in the sky, it remained visible even when the slit was so much contracted that the sodium band of a common fire would have been thinned down almost to its smallest breadth before extinction. Such a diminution of light, however, was fatal to the rest of the spectrum, which was a very remarkable one. With a wider slit a crimson band, bearing a fair amount of contraction, was perceptible in the brighter patches of that hue, with a dark interval between it and the principal green band. On the opposite side of that green band, beyond a second similar dark space, was a considerable extent of greenish or bluish light, quite decided, but so feeble as to leave it undecided whether it was of uniform brightness, or (as I suspected) compounded of contiguous bands; beyond this again was another dark space, leading on to a faintly luminous band, too dim to show colour, but which must have taken its place somewhere in the blue. This band, and the darkness adjacent to it on the less refrangible side, were each about as broad as the intensely vivid yellowish green stripe. Could the light have borne sufficient reduction, we should certainly have had three narrow bright bands in the red, green, and blue, the two latter being wide apart, with either a faint separate continuous spectrum, through part of the interval, or possibly several feeble lines, which the widening of the slit fused into one lengthened area.

The peculiarity, first noted I believe by Otto Struve, was very obvious, that even where the naked eye recognised the strongest and fullest crimson without a trace of green, the greenish yellow band in the spectroscope far exceeded, perhaps three or four times, the red line in visibility. This display was distinguished from almost all that I can recollect to have witnessed through many years, by its very feeble development in all the northern portion of the sky.

Hardwick Vicarage, Hay

T. W. WEBB

WILL you kindly permit me to correct an error which crept into my letter of last Monday on the aurora. The words "western" and "north-eastern" in the 14th line should have read respectively "eastern" and "north-western." Allow me also to call attention to the present condition of Jupiter. On Thursday evening last the equatorial ochre-tinted belt was lighter in colour than I have seen it of late years, but much and distinctly mottled with light and dark clouding, two dark hanging spots on the upper edge, with adjoining elliptical bright patches,

being conspicuous, while the lower dark madder-brown edge was very unequal, being swollen and thick about one-third to the right from the centre, and thinning off towards each end. The dark belt above the equatorial zone had two knots or thickenings of considerable size upon it, and the whole series of belts presented ragged and dentated edges, and, to use the apt phrase of a lady who saw them, had a mountainous " look.

On occasional glimpses I more than suspected a general mottling of the whole surface of the planet, which, moreover, presented a dull appearance, the dark and light belts and spaces not being, as I thought, so well contrasted as usual. The poles were coloured as in ordinary, the upper one warm and ochreish, the lower slate grey. The instrument used was Browning's 81 reflector, full aperture, with inserting achromatic eye-piece 306. A transit of a satellite and its shadow added to the general effect. Guildown, Guildford, Feb. 10 J. R. CAPRON

ON Sunday, the 4th of February, at 10 P. M., I observed the central point of the "corona of the aurora visible that evening to be situated between 1, 64 and 65 Geminorum, in R. A. 7h. 20m. and N. decl. 28. Our latitude is N. 50° 50′ 55′′, and longitude E. 0° 32′ 50′′.

The 66 corona "drifted away very slowly towards the E. against a slight E. wind blowing at the time. Perhaps some of your contributors can calculate the aurora's height from the earth from the above notes, and let us know the result through your journal. J. E. H. P.

St. Leonard's, Sussex, Feb. 12

NOT wishing to trouble you with a long description of the aurora observed by so many on the evening of the 4th, I will confine myself to a few remarks. The spectrum of the brighter portions, viewed through a five-prism direct instrument, consisted generally of the four lines mentioned by Captain Maclear; but when the spectroscope was turned towards the brightest of the curved streamers forming that splendid red and pink star, which so suddenly burst forth at 7:25, some degrees south of the zenith, the relative intensity of the lines was completely changed, the red line becoming more strongly marked even than the green.

The fact that the green line can always be detected, even where the unassisted eye fails to notice any trace of auroral light, might suggest the advisability of a daily observation with a small hand spectroscope for those who are desirous of forming a complete list of all auroral phenomena. Magnetic disturbances are a sure guide in the case of grand manifestations of aurora; but might not a very slight aurora be observable without the magnets being sensibly affected?

On the evening of the 4th the magnetic storm commenced about 2 P. M., and was at its height from 4 to 9, though the magnets were not steady again until after sunrise the next morning. S. J. PERRY

Stonyhurst Observatory

I WRITE a very short account of the great aurora of February 4, as seen by me in the south-east of France, between Chambéry and Macon. It may be of some interest, as a brilliant aurora is very unusual in those latitudes, and this was quite comparable in brilliancy to the auroras of October 1870, and November 1871, which I witnessed in Scotland. The sunset was very clear and bright, but as the sunlight gradually faded, light fleecy clouds appeared in different parts of the sky, with the ruddy tints characteristic of the Northern Lights. As it became darker the redness increased in intensity and extent, overspreading a large portion of the sky, especially towards the zenith, and was streaked with bands of greenish white light. On the eastern horizon a welldefined arch of this pale green light was visible for some time, while underneath the arch the sky was so black that but for a large star shining in the centre of the blackness, I should have supposed that the darkness was due to a heavy cloud. There were, in fact, no true clouds at the time in the sky, and the large stars were everywhere visible amid the shifting masses of nebulous light, which at one instant seemed to be the ruddy reflection of a great fire, and at another to be lighted up by the rays of a full moon. Long streamers of red and green light seemed to shoot up towards the zenith from almost every point of the horizon at various times; but singularly enough there appeared to be fewer displays of this sort in the north than in any other quarter of the heavens. Being, however, in a railway carriage in motion,

and with mountains on every side, the true horizon was not visible, and it was impossible to make very accurate observations. The rosy clouds remained long after the coruscations had died away, but the chief splendour was displayed for an hour and a half after sunset.

If the aurora of this spring was not more brilliant than those of the last two autumns, it was, I think, more remarkable for its sharp contrasts of colour, and for the peculiar "coal sacks," or areas of blackness, which seemed to be actually a part of the aurora as much as the red or green light.

DAVID WEDDERBURN

I HAVE to correct an important error in my account of the aurora of the 4th, published by you on the 8th. I stated that it was finest between 6 and 7. At 9 it appeared to be fading, and I ceased to watch it; but I learned afterwards that it rekindled, and was at its highest between 9 and 10. The colour was still red, and the columns of light met near the zenith. JOSEPH JOHN MURPHY Old Forge, Dunmurry, Co. Antrim, Feb. 12

The Great Comet of 1861

THE following observation may interest your readers. It is taken from a volume entitled, "The Industrial Progress of New South Wales," published by authority of the Colonial Govern

ment.

Under the head of Astronomical Progress is a paper by Mr. Tebbutt, in which he says that, while observing in Australia on the morning of July 1, 1861 (i. e., really, in the afternoon before sunset of our June 30), he noticed the widening out of the branches of the tail of the comet then visible. He remarks that this observation is very interesting when taken in connection with the announcement made by Mr. Hind, that "it appears not only possible, but even probable, that in the course of June 30, 1861, the earth passed through the tail of the comet, at a distance of perhaps two thirds of its length from the nucleus.'

The

There were at least two observers in England of what was probably the opposite effect of perspective (viz., the closing up of the branches of the tail) on the evening of June 30. rapid, angular motion of one of the streamers was separately observed by Mr. George Williams, of Liverpool, and the Rev. T. W. Webb, of Hardwick, the latter of whom has given a detailed account of his observations in the "Monthly Notices of the Royal Astronomical Society," vol. xxii., p. 311. According to these observations, our actual passage through the streamers of the tail must have taken place about sunset on the evening of June 30.

A. C. RANYARD

ON LUMINOUS MATTER IN THE ATMOSPHERE

MUCH has lately been written and lectured on atoms, molecules, organic matter suspended in the air, effects of the light passing through the sky, abstracting its blue colour, and changing it into red. May I therefore be allowed to add some facts which I noticed during a long and careful observation of a hitherto almost unknown phenomenon to which my attention was drawn by chance.

Some years ago I had directed my excellent six-feet of Merz, Munich, towards the sun in order to draw the sun-spots in the camera-obscura. One day (April 27, 1863), when the sun had scarcely passed, and I was pushing the instrument to get its disc again in the field, I was astonished to perceive a mass of luminous little bodies, apparently coming from the sun, and passing altogether with great velocity towards the east. They brightened in a white and sparkling light, and were as numerous as stars; but as their velocity was much too great, and as they disappeared when I followed them to some distance from the sun, I was inclined to take them for little bodies floating in the atmosphere, and getting their light from the sun, an opinion which soon became stronger when I grew aware that I had to draw out the eye-piece some millimetres in order to get them quite clear

and distinct. As I had never heard of the existence of any such bodies, I resolved to give notice to Dr. Wolf, Director of the Observatory at Zurich, who convinced himself of the strange phenomenon, and, encouraging me to persist in my investigations, told me that the late Sig. Capocci, on the Capodimonte Observatory at Naples, had mentioned these little bodies appearing to him under similar circumstances on May 11, 1845. Since that time Prof. Dr. Edward Heis, of Münster, Westphalia, in his "Wochenschrift fur Astronomie," 1869, March 24, also gave full corroboration to this fact. I therefore went on, and uniting the investigation to the daily labour of observing and drawing the sun spots, my arrangement of the camera-obscura improved and ensured these results as well. Convinced of the importance of the phenomenon, I resolved to direct my whole attention to it, and to examine it thoroughly. I decided to find out not only the distance, the size, the shape, the frequency, the velocity, and the nature of the light of these little bodies, but also to take notice of their daily direction by comparing it with the simultaneous direction of winds and clouds. I continued my observations during a period of three years. As I mentioned above, I was obliged to draw out the eye-piece of the telescope in order to have the little objects more distinct. Now, everybody knows that the focal distance of any lens, or system of lenses, such as the telescope is, will differ according to whether the beams come from a more or less distant object. The little bodies did not appear distinct in the focus of the sun; I had to draw out the eye-piece; but if the focal distance was greater, their distance was smaller than that of the sun, and by means of a scale placed on the eye-piece, I soon obtained the result that these little bodies belong to our atmosphere, floating in a stratum of about 4,000 metres down to about 200 metres, the most numerous swarm passing almost always at a distance of not less than 500 metres. Here I remark that for my observations I had chosen the time of the sun being in, or about, the meridian, for then I was sure to have its light as strong, and the sky as clear as possible, while mostly preferring a magnifying power of only 48 diameters.

Taking the little bodies in the right focus, I was enabled not only to draw their shape, which I found very various, but also to measure their apparent diameter, which did not differ less, and depended much on distance, the nearer ones being larger, and, as I learned from the scale the accurate distance of every one, I calculated their diameter to vary from 10 to 59 millimetres, the average being_32 millimetres. Their shape was very various, too. The greater number were oblong, angular, resembling flakes, some few were orbicular, while some smaller ones were star-shaped, with transparent arms.

With respect to their frequency, I was surprised to find on certain days, especially in April and May, an incalculable number of little bodies in the field of the instrument, passing without interruption for hours. In general I found their number to be connected with the purity of the sky; and every day I noticed the average, the daily minimum occurring in the morning and evening hours, the maximum in the noon-tide hours; also the annual minimums in the summer and winter months, the chief maximum from April 20th to May 15th, the second, much lower maximum in August and September. I often saw their number increase soon after clouds had passed.

The velocity of the bodies, irregular in the lower strata, being about 2 metres in a second, became greater and more regular in the higher ones, where, for instance, at a distance of 3,000 metres, I found them to pass 8 metres during the same period, a rapidity agreeing closely with that of the cirri, which often passed at or above this distance. Whether far or near, all these little bodies glittered in a magnificent white light behind the sky, but as it retreated farther from the sun its blue colour became darker, the light of the bodies consequently diminished, and was

usually considered as pertaining to the domain of dry Science. In so doing he seems also to have been assisted by having adopted a system of classification, or rather grouping, of the subjects which form his separate chapters, which, although not strictly scientific, is preferable in the present instance, as being more in accordance with The work, besides being well got up, is abundantly popular notions.

The two maps indicating the on popular Science, several of which have lately been rendered into English. distribution of coal and metallic deposits in Great Britain and the Americas respectively are not on a par with the rest, owing to errors of omission; thus, amongst others, neither the central lead-producing district of Wales, nor

CARBONIFEROUS FOREST, CARBONIFEROUS PERIOD