April 29, 1880] 



NATURE 



609 



former, and demands that reason shall be shown for not 

 diverting to the service of the latter at least a large share 

 of attention. 



Remembering that measurement of arcs and elaborate 

 study of the earth's irregularities by the plumb-line never 

 can extend much beyond the continents and larger 

 islands, and never will extend far in advance of civilisa- 

 tion ; while pendulums can, and assuredly will some day, 

 form part of the equipment of every scientific exploring 

 party, it does seem passing strange that we should still be 

 discussing the ratio of the axes of a convenient figure of 

 reference (p. 287) as a more important question than the 

 actual nonconformity of the earth to some approximate 

 figure of known form. 



What we would fain see, as the geodetical fruit of first- 

 class surveys — if not done, then attempted ; and if not 

 even attempted, then at least inculcated as to be done or 

 attempted — is, a comparison of the earth's surface, as 

 actually measured, with some provisionally adopted form, 

 showing where possible the relative position of the actual 

 zenith, as determined by astronomical observations, with 

 respect to the formal zenith. And then, a discussion of 

 such results, showing, either a traceable continuity of the 

 irregularities of the actual surface, if such exists ; or 

 evidence of discontinuity such as to justify a presump- 

 tion that the irregularities are too small in area to be 

 susceptible of study without closer distribution of 

 stations. 



Thus we might haply arrive at one of two conclusions 

 — that large irregularities exist which may be mapped, or 

 that the irregularities are such as to demand special 

 investigation by a recurrence to observation in selected 

 localities. 



If to this suggestion it is objected that the thing has 

 been done— and we know that the irregularity in the 

 neighbourhood of Moscow has been investigated in some 

 such way— we reply that, even so, a short paragraph 

 noticing the fact (p. 288) is but a meagre presentation of 

 what seems to us one of the principal results of methodic 

 geodesy. 



And now that we have done and have to lay down the 

 pen, it is with a feeling of regret and a sense of incom- 

 pleteness. The book deserves so much better than we 

 have said of it. We have identified ourselves too entirely 

 with the student looking for special instruction and too 

 little with the author giving the best he had, and have 

 quarrelled with him because it was too good for our 

 needs. Once more be it said that the subject is too large 

 for a single work— it needs a series. It is but the absence 

 of a few apologetic words that has given this sense of a 

 subject approached at many points only as it seems to be 

 immediately quitted, in favour of others which have more 

 attraction to the author. Now that he has dwelt on them, 

 may he resume his task, and enlarge where we have shown 

 the need. j. Herschel 



OUR BOOK SHELF 



The Fauna of Scotland, with Special Reference to 



Clydesdale and the Western District— Mammalia. By 



E. R. Alston, F.L.S. (Glasgow: The Natural History 



Society of Glasgow.) 



THE Natural History Society of Glasgow, having resolved 

 to publish a catalogue of the fauna of the western district 



of Scotland, have secured the co-operation of Messrs. 

 Alston, Young, Cameron, Robertson, Binnie, and Lums- 

 den. Already one part of the catalogue of the Crustacea 

 and one part of the catalogue of the Hymenoptera have 

 been issued, and these have now been followed by the 

 present part, treating of the Mammalia. The Society is 

 doing a good work, and will be fortunate if all the parts 

 as published come up to the standard of the one now 

 before us. In the nomenclature of the Mammals, of 

 which fifty-one are recorded, the author endeavours to 

 reconcile the spirit and the letter of our British Associa- 

 tion rules. Without entering into any details of descrip- 

 tion or economy, he has carefully worked out the geogra- 

 phical distribution of each species. A very interesting 

 list is given of extinct and recent Scottish Mammals, 

 arranged in the probable order of their arrival from the 

 southward. 



LETTERS TO THE EDITOR 



[The Editor does not hold himself responsible for opinions expressed 

 by his correspond! nts. A'either can he undertake to return, or 

 to correspond with the writers of, rejected manuscripts. A'o 

 notice is taken of anonymous communications. 



[The Editor urgently requests correspondents to keep their letters as 

 short as possible. The pressure on his space is so great that it 

 is impossible otherwise to ensure the appearance even of com- 

 munications containing interesting and novel facts.} 



Auroral Response in America 



When the full burst of auroral displays is upon us, and one 

 brilliant demonstration treads close on the heels of another, there 

 may be some trouble in ascertaining which corresponds to which 

 on opposite sides of the earth. But the opening of the new 

 cycle-season by the arc which I described in your pages on 

 March 17, has proved so isolated a phenomenon in time, that it 

 cannot be confounded with any other either before or since. 

 And while your subsequent notice of the disturbance of the 

 magnets at the Royal Observatory, Greenwich, on the same 

 night, proved that the aurora seen in Edinburgh was an earth-ball 

 phenomenon, and not a mere local atmospheric glimmer, the 

 following letter, which has just reached me from Canada, shows 

 a remarkable correspondence to have prevailed there. 



The letter, written to me by Lieut. Col. G. E. Bulger, late 

 10th (North Lincoln) Regiment, from Montreal on April 10, is 

 word for word simply thus : — 



" I have noticed your account (Nature, vol. xxi. p. 492) of 

 the aurora seen in Edinburgh on the 17th ult. ; and it has occurred 

 to me that it might interest you to hear of a similar display which 

 I observed at this place on the same date. Your description 

 would apply very well to the one witnessed here, excepting that 

 the arch was higher in the sky, and its centre about N.E. The 

 darkness below the light was very marked, although the moon 

 was shining brightly at the time. Auroras have been singularly 

 rare here this year, and that referred to is the only one I have 

 seen or heard of since my arrival in August last. The weather 

 on March 17 was bright and fine, with detached clouds, and a 

 light N.W. breeze. The barometer (aneroid) at 9 p.m. was 

 30-36, therm. I4°'7." 



Thus far Col. Bulger ; and now we have only to wait the 

 arrival of Australian meteorological reports to ascertain whether 

 south responded to north, as well as west to east, on the occasion 

 of that remarkably isolated auroral display, abundantly observable, 

 yet observed by so very few persons, in this country on March 17 

 last. Piazzi Smyth 



15, Royal Terrace, Edinburgh, April 26 



The Antiquity of Oceanic Basins 

 I AM much obliged to my friend Prof. Alex. Agassiz for 

 reminding me that his distinguished father, when reporting on the 

 deep-sea dredgings carried on by the United States Coa-t Survey 

 in 1866-68, explicitly endorsed the views previously put forth by 

 Prof. Dana (to whom, however, he made no reference) as to the 

 geological antiquity of the American Continent and the probable 

 determination of the general outlines of the present Continental 

 elevations and Oceanic depressions at the very beginning of the 

 formation of inequalities upon the Earth's surface. 



