554 



NA TURE 



[April 12, 1894 



S):ead of the " thermophytes" in Central Europe since 

 the "fourth ice-period" ; and a third with the division of 

 Central Europe into floral districts ; followed by some 

 seventy pages of explanatory remarks on the points 

 raised in the preceding chapters. Unfortunately for 

 those who would wish to consult this book, it has neither 

 index nor headings of any kind. There is no attempt 

 whatever to classify the facts and data ; no rnap, no 

 summary, no digest, no general conclusions ; indeed, 

 no htip at all for the reader desirous of knowing what 

 the writer has arrived at, or is leading up to. He begins 

 with the assumption, that only very few of the plants 

 which now inhabit Europe were already here in Miocene 

 times, and that a large majority of the present vegetable 

 inhabitants consist of immigrants and such as have 

 originated within the territory since the beginning of the 

 Pliocene period. The homes of the migrated species he 

 would seek in Arctic America, but chiefly in Asia ; and a 

 very small number he considers have migrated from 

 North Africa. In illustration of migrations the author 

 gives full details of the present distribution of a small 

 selection of plants ; but only in words, so that it is a 

 study to trace the areas. Having thus called attention 

 to this work, we must leave it to the reader with leisure 

 to follow the writer through his four ice-periods, and the 

 present dis:ribution of the leading elements of the flora 

 of Central Europe ; and we may add, that he will find 

 much interesting matter. 



Elementary Metal Work. By G. C. Lei and. (Whittaker 

 and Co., 1894.) 



This book is devoid of scientific or general interest, 

 merely treating of certain kinds of decorative metal work 

 which can be executed by amateurs and children, and 

 which, as a general rule, we would far rather be without. 

 There have been instances, however, in which metal 

 working at home, directed by energetic people of taste 

 and leisure, has been found to greatly benefit working 

 men and their families who are forced to be com- 

 paratively idle in winter. In a certain charming spot in 

 the Lake District, where such objects are readily disposed 

 of to toarists, the results have been most satisfactory, 

 and we wish some such home industries could be intro- 

 duced into parts of Ireland and Scotland frequented by 

 visitors in summer, where the enforced winter idleness 

 produces an amount of poverty painful to think of. 



J. S. G. 



LETTERS TO THE EDITOR. 



yihe Editor doss not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications. "^ 



Earth Currents. 



The Astronomer Royal was kind enough to show me the 

 permanent photographic records of earth currents during the 

 great magnetic storm on February 20-21, and they indicated 

 so unmistakably such rapid and violent alternations, that I sup- 

 plied our principal relay stations with telephones and with 

 instructions to insert them in circuit whenever they observed 

 indications of disturbances. This happened on March 30-31, 

 during the display of the Aurora Borealis. Mr. Donnithorne, in 

 Llanfair P.G., Anglesea, reports: — "At 2.0 a.m. (Saturday) 

 the telephone receiver was again tried, and then ' twangs ' 

 were heard as if a stre'.ched wire had been struck, and a kind of 

 whistling sound. The strength of the earth current was 177 

 milliamperes." Mr. Miles, in Lowestoft, reports :— " Noise on 

 408 (Liverpool-Hamburg) wire seemed like that heard when a 

 Hy-wheel is rapidly revolving," and "sounds in telephone 

 appear like heavy carts rumbling in the distance." Mr. 

 Scaife, in Haverf )rdwest, reports: — "March 3r, 2.5 a.m. 



NO. 1276, VOL. 49] 



Earth currents on all wires ; wires completely stopped. . . . 

 Peculiar and weird sounds distinctly perceived, some highly- 

 pitched musical notes, others resembling murmur of waves on a 

 distant beach. . . . The musical sounds would very much 

 resemble those emitted by a number of sirens driven at first 

 slowly, then increased until a ' screech ' is produced, then 

 again dying away. Duration of each averaged about twenty 

 seconds." These experienced observers, situated at three dis- 

 tant points, and perfectly acquainted with the ordinary in- 

 ductive disturbances on telephone circuit-, simultaneously 

 observed and independently recorded their own impressions of 

 peculiar sounds exerted in telephones by very rapid alterna- 

 tions or pulsations of currents which accompanied or were 

 consequent on sun-spots, earth currents, and the Aurora 

 Borealis. W. II. Preece. 



G.P.O., April 9. 



The Aurora of March 30. 



I VENTURE to supplement the reference in Nature to the 

 Aurora of March 30, by a brief account of an observation made 

 by me at Bristol. 



At about 10.30 p.m. I noticed against a dark blue sky a single 

 narrow rose-coloured ray stretching from between a and /3 Ursa 

 Majoris to the neighbourhood of 5 Aurigse, and slightly beyond 

 it. It was speedily joined by a second and then by a third ray, 

 apparently diverging from a common centre about 5 degrees 

 beyond o and /3 Ursa Majoris. The three rays gradually became 

 less divergent, and merged into one broad beam, which uhi- 

 mately faded away : the whole phenomeni lasting about 5 or 6 

 minutes only. At the same time there was a greenidi-white 

 luminosity on the N.N.W. horizon, suggestive of a belated and 

 misplaced sunset. I understand that this had endured for along 

 time, perhaps an hour or more. J. Ryan. 



University College, Bristol, April 9. 



Crystal ine Schists of Devonian Age. 



In a recent number of Nature (vd. xlix. p. 435) Pi-of. 

 Bonney writes: — "Speaking for ourselves we tinnk he (Prof, 

 van Hi-e) is disposed to ... . admit on too slight evidence 

 that in ' Silurian, Devonian, and even later lime-, completely 

 crystalline schists hive been produced over large areas ' ; for in 

 the past this as sen ion has been so often made, and so often 

 proved erroneous, that on the principle, ' once bit, twice shy,' 

 we are disposed to be a little sceptical." 



Mere assertions in geology, as in gf-neral science, are scarcely 

 worth the trouble of contradicting ; but in one cas"*, at least, the 

 evidence; of the existence of completely cr3Stalline " Devonian," 

 schists docs not rest on mere as-ertion. 



I published certain microscopic evidence in favour of the 

 Devonian a.;e of the schi-ts of the Start and Bolt district in the 

 Geological Magazine in 1892, and as Prof. Bonney vvoukl not 

 condescend to weigh the said evidence, but contented himself by 

 attempting to defend his own position by " abusing plaintiff's 

 attorney," I proceeded to dissect his own argument for the 

 Archsean age of the rocks in question in a separate jublication. 



Until the facts and arguments advanced in support of ihe 

 " Devonian " age of these crystalline rocks, and the argu- 

 ments against Prof. Bonney's rival hypothesis, (the latter 

 based on a brief week's investigation of a district which has 

 puzzled geol 'gists for o'er half a century) are all fairly met, I 

 must deprecate any attempt being made to lead the readers of 

 )OJr journal to believe that the doctrine of the "Devonian" 

 age of the Devonshire schists has been " proved erroneous." 



Torquay, March 23. Arthur K. Hunt. 



P. S. — Whsn the above was written I had not seen the 

 remarks of the Director General of the Geological Survey on 

 the metamorphic area of South Devon, published in your issue 

 of March 22 (Naiuke, vol. xlix. p. 497). 



William Pengelly. 

 Prof. Boyd Dawicins, in his otherwise excellent obituary 

 of Pengelly, refers to the Bovey Tracey beds as a Miocene 

 Lake deposit. They are, however, not lacustrine but fluviatile, 

 consisting of current-bedded coarse grits alternating with 

 lignitic muds, such as are deposited in stretches of still water 

 when the main current cuts itself a new channel. Litho- 

 logically these beds are identical with those of Corfe and 

 Bournemouth, and there is no reason to doubt their being the 



