302 



NATURE 



[Feb. 15, 1872 



number of times that aurora was visible with the extent of 

 country over which it was observed, and the numbers stand 

 thus : — 



January ... ... 297 



February ... ... 42 '5 



March... ... ... 35'0 



April ... ... ... 27-5 



May ... ... ... 4'8 



June ... ... ... O'O 



July ... ... ... 0-5 



August ... ... I2'6 



September ... ... 36 'O 



October ... ... 494 



November ... ... 32 '4 



December ... ... 28 '8 



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 t\vo maxima of the annual cycle October 

 has rather the advantage. 



The hghtning return, prepared on the same principle, is not 

 uninslructive to be compared against the aurora ; for, though 

 both in its aerial 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 tlie 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 phy- 

 sical signification. The actual numbers are these : — 

 January ... ... 24 "o 



February ... ... I4'4 



March... ... ... yo 



April ... ... ... I5'4 



May ... ... ... 37-4 



June ... ... ... 480 



July ... ... ... S3'2 



August ... ... 384 



September ... ... 22 '4 



October ... ... 20'8 



November ... ... 150 



December ... ... i5'o 



C. PiAzzi Smyth 

 t5, Royal Terrace, Edinburgh, Feb. 10 



The Aurora of February 4 



I WILL not attempt to describe the wonderfully gorgeous dis- 

 play of aurora which I witnessed on Sunday night, February 4. 

 I merely wish to mi;ntion a circumstance connected with it which 

 may have S-ime interest. I was watching for the zodiacal light 

 at about 5.30, and, havin;:; 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 liglU of 

 an aurora. I-'rom 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 alter 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. I 

 nevtr witne<;sed or read of such a display m these latitudes. 

 ^Yith one of Browning's small star spectroscopes the spectrum 

 consisted of a small portion of brilliant red, then a bright b.md 

 rather close to it, and then two others beyond ; the two latter 



being rather nearer together than the first and second ; that at 

 the more refrangible end being the fain'est, and that near the 

 red the strongest. I enclose a sketch showing the spectrum, the 

 slit being wide open. 



The maximum display was between 6.4^ 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 dis- 

 play was going on ; and at II P.M., in spite of d^^nse 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' o" N., long. o°2o'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 con- 

 flagrarion. Shortly after, an almost complete auroral arch, of 

 faint orange red light, similar to that at first observed, was 

 noticed, e.\tending from E., above and partly embracing 5, €, and 

 f 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 5, a, and k 

 Pcrsei. At 5h. 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 Sh. 25m. 



John James Hall 



Fulwell, near T\\ickenham 



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 de- 

 scription, the landscape and the countenances of those standing 

 near beingvisibly 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. 

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

 and the stars shining with their usual brightness. On the forma- 

 tion of the corona a sheet of fan-shaped sea-green haze shot from 

 it in a N. direction, spreading rapidly as it advanced, but did 

 not proceed for more than 20", when it suddenly disappeared. 

 The streamers were remarkably steady throughout and straight, 

 unUke 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, wi h a reddish glow- 

 in some places, and a few resplendent beams of white light from 

 the E. chiefly. At a quarter to eight red -trcamers became 

 visible m a N. direcii m, 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 obicured 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 daik. 

 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. 



Thomas Fawcett 

 Blencowe School, Cumberland, Feb. 5 



