February i8, 1892] 



NA TURE 



365 



lightly increased until about 5.40 p.m., whilst both horizontal 

 and vertical forces similarly increased in intensity, more espe- 

 cially between 4 and 6 p.m. They further diminished in forco 

 after 10 p.m., and their changes became very rapid from 12 

 midnight to 2 a.m., whilst at the same time the declination 

 proceeded to its extreme westerly position. Subsequently, the 

 fluctuations in magnetism became much reduced in extent, and 

 the whole disturbance gradually diminished and died out about 

 4 p.m. of Sunday. 



The Kew magnetometers were not able to record the complete 

 extent of the vibrations to which free needles were subjected, 

 nor could the entire change of force be secured in the field of 

 the instrument. The limits, however, clearly recorded were 2° 

 of declination from •1760 to '1830 of horizontal force, and from 

 •4350 to '4420 units of vertical force expressed in C.G.S. 

 measure in absolute force. G. M. Whipple, 



Superintendent. 



Kew Observatory, Richmond, Surrey, February 16. 



The New Star in Auriga. 



Prof. Copeland has suggested to me that as I am the 

 writer of the anonymous postcard mentioned by you a fortnight 

 ago (p. 325), I should tell your readers what I know about the 

 Nova. 



It was visible as a star of the fifth magnitude certainly for 

 two or three days, very probably even for a week, 1; efore Prof. 

 Copeland received my postcard. I am almost certain that at 

 two o'clock on the morning of Sunday, the 24th ult., I saw a 

 fifth magnitude star making a very large obtuse angle with )8 

 Tauri and x Aurigse, and I am positive that I saw it at least 

 twice subsequently during that week. Unfortunately, I mistook 

 it on each occasion for 26 Aurigse, merely remarking to myself 

 that 26 was a much brighter star than I used to think it. It 

 was only on the morning of Sunday, the 31st ult., that I satisfied 

 myself that it was a strange body. On each occasion of my 

 seeing it, it was slightly brighter than x- How long before the 

 24th ult. it was visible to the naked eye I cannot tell, as it was 

 many months since I had looked minutely at that region of the 

 heavens. 



You might also allow me to state for the benefit of your 

 readers that my case is one that can afford encouragement to 

 even the humblest of amateurs. My knowledge of the techni- 

 calities of astronomy is, unfortunately, of the meagrest descrip- 

 tion ; and all the means at my disposal on the morning of the 

 31st ult., when I made sure that a strange body was present in 

 the sky, were Klein's "Star Atlas," and a small pocket tele- 

 scope which magnifies ten times. 



Thomas D. Anderson. 



21 East Claremont Street, Edinburgh, February 13. 



Nacreous Clouds. 



In the morning of the 30th ult. there was a magnificent display 

 of the nacreous (or iridescent, as they were first called) clouds, 

 which formed such a striking feature of the sunset and sunrise 

 sky for some days in succession in December 1884 and 1885 

 <vol. xxxi. pp. 148, 192, 316, 360, &c.). They were not exactly 

 the same in appearance, but I should say they were of the same 

 nature. I had not seen them in the interval of six years, and 

 have only noticed them lately on the one day mentioned. They 

 were confined to the southern part of the sky. As the sun rose 

 higher their colours were less visible, and the clouds disappeared 

 about noon ; though in the afternoon some reappeared, but 

 never became very striking. At 5h. 44m. G.M.T. there was 

 only one group, which was too far from the sun to show any 

 nacreous colours ; its centre was about at hour-angle ih. 2m. 

 west, and declination 23^" south. Although conspicuous they 

 were no longer very bright, and I should say the sun was 

 evidently not shining on them, for they were the same bluish- 

 green colour as the western sky, and I apprehend were 

 illuminated by the sky. T. W. Backhouse. 



Sunderland, February 9. 



The Cause of an Ice Age. 



In his very kindly review Prof. Darwin thinks I might have 

 stated my argument with more completeness if I had preserved 

 its generality by the use of a symbol instead of taking a special 

 case. 



No doubt in many ways the treatment he suggests would have 

 been better. It would, for instance, have enabled me to prove 

 the case a fortiori. Perhaps, however, the reasons given in 

 the chapter explaining "why the book has been written" may 

 show that for the object I had in view the method actually used 

 was appropriate. 



I am also much obliged to the same friend for pointing out 

 that the astronomical theorem proved in the appendix had 

 been given by Wiener, " Uber die Sliirke der Bestrahlung " 

 {Zeitschrift der Oesterreichischen Gesellschaft fiir Meteorologie, 

 vol. xiv., 1879, p. 129). Robert .S. Ball. 



Observatory, Co. Dublin, February 9. 



Ice Crystals. 



With reference to the letter on the subject of ice crystals 

 which appeared in Nature of the 4th inst. (p. 319), it is 

 perhaps worth mentioning that a paper on the subject, entitled 

 " Eine Eiskrystallgrotte," by C. A. Hering, appeared in Groth's 

 Zeitschrift fiir Krystallographie und Mineralogie, Band xiv. 

 (1888), pp. 250-253, and Plate vi. 



The crystals occurred in an old mine on the Waschgang near 

 Dollach in Carinthia. Large fans, as much as 300 mm. long x 

 200 mm. broad, of ice-crystals grow out horizontally from the 

 vertical walls. The stalk, consisting of a series of hexagonal 

 prisms, hollow, like thermometer-tubes, was in the middle 

 25 mm. thick and thickened towards the point of attachment to 

 the rock. The fan surface was a large hexagonal plate with 

 strong prismatic ribs running from the centre to the angles. 

 The interspaces between the ribs were filled by prisms arranged 

 with the greatest regularity. Upon the ribs of the fan either 

 single crystals or funnel-shaped structures with step-like sides 

 consisting of prisms were borne. The individual crystals were 

 almost all thick tabular forms, with prism, basal pinacoid, and 

 rhombohedral faces. Bernard Hobson. 



Owens College, Manchester, February 8. 



A Rare British Earthworm. 



In the summer of 1890, during my researches into the 

 Vermes of Cumberland, I discovered a species of earthworm 

 which proved to be new to Britain {Lumbrictis Eiseni, Levinsen). 

 As I have recently had the good fortune to receive specimens 

 of the same worm from another part of the country, it seems 

 desirable to place the same on record. A correspondent writes 

 from Gloucestershire as follows : — 



" Last Saturday (January 30, 1892), I walked up to one of 

 my favourite woods here on the Cotswolds, about 700 feet above 

 the sea — a damp old beech wood, the Frith Wood of Withering's 

 "Arrangement," seventh edition, 1830 — and seeing a stump of 

 some 10 inches diameter with a growth of the black ' Candle 

 Snuff Fungus ' on it, I examined the rotten wood, which gave way 

 to the pokes of my stick. Among this rotten wood I saw some 

 earthworms, two or three of which I inclose, hoping they may 

 prove an addition to our worm fauna." 



I have placed on record all the known earthworms of 

 Gloucestershire in 7'he Field Club for 1 89 1, to which this may 

 now be added. The worms were small, but in good form for 

 identification, and prove to be specimens of Eisen's worm. I 

 have, unfortunately, been unable hitherto to consult Levinsen's 

 original description ; nor have I been able to obtain Rosa's 

 memoir published in the Boll. Mus. Zooi., Torino, 1889 (vol. iv.. 

 No. 71). I am therefore obliged to content myself with a 

 description of the specimens in my possession. 



Lumbricus Eiseni, Lev., as found in Britain, is a small species 

 of earthworm, measuring about li inches in length when adult. 

 It has the usual colour of the allied species — the purple and 

 red worms — being of a ruddy hue, with iridescence. The 

 clitellum or girdle, which occupies segments (24) 25 to 31, is a 

 reddish-brown, being lighter in colour than the anterior portion 

 of the worm's body on the dorsal surface. Ventrally the worm 

 is, as usual, of a lighter shade. No ttibercula pubertatis have 

 been seen under the girdle, but the first dorsal pore in every 

 specimen examined is clearly detected behind the 5th segment. 

 This may be indicated by the fractional sign % ; and as the most 

 recent researches tend to demonstrate the constancy of this 

 character for each species of earthworm, it is important to note 

 the same. The lip or prostomium has the complete mortise and 



NO. I 164, VOL. 45] 



