56 



NATURE 



[May 1 8, 1882 



greater than the normal by more than t-icolh part. Finally, 

 the normal value was gradually reached again at 7I1. 30m. 



In the second magnetic storm, the range of the declination 

 movements was i° 30', of the horizontal force about 1-501)1 part 

 of the whole, and of the vertical force about 1120th part. 



Thus the vertical force disturbance on April 19-20 was com- 

 paratively small ; that of the vertical force on April 16-17 is 

 characteristic of the greatest storms, and ; ince the great dis- 

 turbances of 1872, February 4, and those of October 4 of the 

 same year, no magnetic storm lias been recorded equal to this. 

 Earth-currents were shown throughout both -t 



W. H. M. Christie 



Royal Observatory, Greenwich, May 8 



Hypothetical High Tides 



I regret that I am not able to accept the criticisms of Mr. 

 <_'. Callaway on my notice of Prof. Ball's lecture. I have studied 

 the effect of tidal and wind waves on many coasts through many 

 years, and my observations do not warrant the statements he 

 make-. Every schoolboy knows the distinction between waves 

 of undulation and translation, and it is in no -ense true that I 

 have confused them. With waves of undulation such as occur 

 in mid ocean we have nothing to do in this discussion, but it 

 cannot be unknown to .Mr. Callaway that all such waves when 

 reaching a shore, become waves of translation, and more or less 

 powerful denuding agents. If he will have the kindness to 

 refer t > my " Report on the Geology of Ohio," vol. i. pp. 52, 

 &c, he will find that I have done ample justice to the efficiency 

 waves as agents of geological change. The great tidal 

 current rushing around the earth, with which lie credits me, 

 ily in his own imagination. I have suggested nothing of 

 the kind, but the rapid ebb and Sow over the shores of continents 

 of tidal waves several hundred feet in height must necessarily act 

 with great violence upon such shores, and I insist that such tidal 

 pictured by Prof. Ball would have left a very different 

 record from that we find in our Palaeozoic rocks. Some of our 

 American Silurian strata were deposited on shores that faced 

 toward the east, where they had an unbroken stretch of several 

 thousands of miles of ocean over which the tidal wave would 

 come to them without obstruction, and there the maximum effect 

 of such tides as Prof. Kail describes would be produced, but no 

 traces of them are found. 



1 am aware that the reef-building corals of the Devonian were 

 zoologically distinct from any now living, and for that reason 

 ied my inference from them; but we have satisfactory 

 evid nee that the Devonian coral reefs of Ohio and Kentucky 

 were formed along a shore &ai in a warm ?ca, like the reef- 

 building corals of the present day. and there are many reasons 

 < ving that their mode of life was the same. 

 int made by Mr. Searles Wood in regard to the coal, 

 lected to by Mr. Callaway, is well taken, for we know 

 that the great coal marshes of America were located just at the 

 lo time were inundated by the sea and 

 covered with sheets of marine limestone. It requires no argu- 

 ment to show that the growth of the Carboniferous forests and 

 lion of beds of peat— now coal — could not have taken 

 place with tides rising one-half or even one-fourth of the height 

 of tho e described by Prof. Ball. 



On carefully reviewing the facts which suggested my objection 



Ball's theory, I am compelled to reiterate the statement 



before made, that on the east coast of North America the geo- 



nony against 

 iidc theory, and that at least since the Archaean ages no 

 tides have Swept this coast like those required by Prof. Palls 

 theory, even as modified by Mr. Darwin. 



New York, April 10 J. S. Newberry 



Aurora Borealis 



A POLAR aim ible activity and brilliancy was 



it 11. 15 last night. The centre of energy at 



the time of origin was under Cassiopiea, a highly luminous 



; upwards from ind covering, but 



not hiding the star- in that con tellation. Brilliant white fliek- 



and rays, arising from the horizon, quickly 



iwards the north-west, and an irregular shaped mass of 



light, of an altitude of 45', and many degrees in 



breadth, i ihe northern hemisphere from 



and the mass of 



crimson-c loured vapour the sky was of a light green hue, and 

 upwards, through this area of greenish light, the rays and 

 streamers shot. 



During the period of greate-t energy, a beam of vivid light 

 arose towards the north-west, was projected over Gemini, and 

 quite extinguished the light of the two large stars in that con- 

 stellation. About midnight the meteor faded. Soon afterwards 

 the sky became overcast. Throughout the day the wind had 

 been blowing briskly and coldly from a point in the north-east, 

 barometer, highest during the day in the shade, 60 ; aneroid, 

 30 2. In the afternoon, curious slender-rayed cirri from the 

 north-west, generally indicative 10 my mind of auroral disturb- 

 anie, crossed the northern sky towards the zenith. To-day, 

 detached clouds and blue sky, and the wind is blowing stiffly 

 and icily from the same point. Barometer and aneroid >ame as 

 yesterday, the latter inclined to full. 



An auroral display of the like splendour and activity is very 

 rare, if not wholly unknown in this locality at this time of the 

 year. X. 



Worcester, May 15 



At 1055 p.m. last night, I observed a very beautiful aurora 

 borealis, consisting mainly of three beams, nearly vertical, and 

 then parallel to the direction of the stars a and 5 of the Great 

 Bear. They moved sljwly towards the east, and about 11-5 

 faded away. About II o'clock they were very liril iant, and tin- 

 central beam, then quite close to the Polar star presented a 

 slightly purple or violet colour, as represented in the sketch 

 inclosed. Niar the earth, and at about i5°to 20° elevation, 

 there was a mass or cloud of suffused light, from which the 

 beams seemed to rise. It seems that an aurora was also seen 

 about a fortnight ago from J lublin. The wind has been easterly, 

 and to-day is somewhat col ler than yesterday. 



J. r. O'Reilly 



Royal College of Science, Dublin, May 14 



Spectrum of Wells' Comet 

 The continuous spectrum of this co tet, especially of the 



nucleus, is remarkably bright. I observed it on April 18 and 

 May 6 and 15. There were at least three bright bands, and 

 perhaps more. 1 believe the usual three were vi-ible, but they 

 were so indistinct that 1 did not observe their positions. The 

 middle one was much the brightest, and the only one plainly 

 visible. 1 never saw a comet in which the blight bands were s . 

 faint, relative to the continuous spectrum. 



May 16 T. W. BACKHOUSE 



The Recent Violent Storm 

 May I ask your permission to insert from me a curious cir- 

 cumstance, which came u ider my notice, soon after the tremen- 

 dous storm which took place on Saturday, April 29 last. On 

 ol the windows of the house in which I reside 

 I perce ved a very singular appearance upon them, somewhat 

 resembling a deposit from milk. On looking at it through a 

 microsc >pe I discovered a number of very beautiful crystals, 

 which, without doubt, were caused by the spray from the sea, 

 as on applying it to the tongue, there was a strong taste of salt. 

 The distance the spray must have been carried on this occasion 

 could nit have been less than sixty miles, taking into considera- 

 tion the Course of the wind, which was south-west. 



Nathaniel Waterall 



Waddon, Croydon, Surrey, May 15 



The Cuckoo 

 Is it a normal habit, or only an erratic freak of that quaint 

 bird, the cuckoo, to sing at night. On the night of Monday, 

 the 8th inst., I first heard, at 10 p.m., three or four calls, but 

 took little notice of it, thinking the bird had been startled from 

 his dreams, but in a short time he recommenced, and went on 

 ly with short intervals of silence, until 12 or I, 

 precisel) as by day. 



It was a dark night with only dim starlight. I should like to 

 iher others have remarked tin, nocturnal loquacity in 

 the cuckoo. This particular bird has usually commenced his 

 1 all at about 4 a.m. J. E. A. Brown 



May 1 1 



