August I, 1878] 



NATURE 



355 



these heights are remnants of an ancient volcanic centre 

 of later date than the Carboniferous Limestone has been 

 made satisfactorily evident by the careful maps and sec- 

 tions of the Geological Survey. The rocks differ a good 

 deal from those of the Tertiary volcanic region of Antrim. 

 Mr. Hull thinks that they have not the same " appear- 

 ance of recentness" as the latter, and as Permian 

 volcanic rocks have been recognised in the south-west of 

 Scotland, he thinks it a pity that the Emerald Isle should 

 not have a share of them, and so he would fain regard 

 the peaks of Mourne and Carlingford as the stumps of 

 volcanoes which were blazing in the west when those of 

 the Rothliegende were active in central Germany. All 

 that, in the present state of our knowledge, can be affirmed 

 about these rocks, is that they are later than the Car- 

 boniferous Limestone. They may be called Tertiary with 

 about as much probability as Permian. 



The wrongs of Ireland go back at least as far as 

 the close of the Carboniferous period. Mr. Hull, with 

 praiseworthy calmness, sketches the process by which 

 his country has been despoiled of its once extensive coal- 

 fields, and, while pointing regretfully to the few little 

 scraps left here and there to tell of former mineral wealth, 

 doomed to irretrievable destruction before either Celt or 

 Saxon set foot upon the land, he consoles us with the 

 just reflection that " the character of the inhabitants and 

 their destiny as an agricultural or pastoral people were 

 fixed altogether independently of social or political con- 

 siderations." The author, following Jukes in his ex- 

 planation of the history of Irish rivers, gives some 

 interesting details regarding a few of the principal water- 

 courses of the country. His account of the numerous 

 lakes of Ireland is well arranged, but provokingly brief. 



In the third part Prof. Hull deals with the glaciation of 

 Ireland, and presents us with a readable summary of what 

 is known up to this time on that subject, his narrative 

 being accompanied by a small coloured map, on which 

 the chief lines of ice-movement are drawn. Though 

 certain tracts are marked on this map as "snow-fields," 

 it is to be presumed that at the time the rocks were being 

 striated in the directions there indicated, the whole island 

 was one vast snow-field, with no boundary of any kind 

 between the tracts here separated and the rest of the 

 country. In a closing chapter the author brings before 

 his readers the days of the mammoth, red-deer, rein-deer, 

 great Irish deer, wolf, bear, and wild boar. To that 

 venerable Irishman, the Megaceros hibernicus, a couple 

 of pages are lovingly devoted, where we learn that the 

 reason why he flourished so abundantly in the sister 

 island was "the absence of many of the natural enemies 

 \ with which he had to contend in Britain and Europe.'' 

 Happy days these must have been ! Who knows but 

 Megaceros may have lived in brotherhood with the 

 earliest human Irishmen until in after ages the "natural 

 enemies " of both crossed over to them from Britain. 



The volume is certain to prove useful. To geologists 

 at a distance it presents in brief and readable form a 

 compendium of all that is most striking and interesting in 

 Irish geology. To those who can avail themselves of the 

 numerous opportunities now afforded of visiting and 

 travelling in Ireland it forms an admirable guide-book. 

 Its appearance before the approaching meeting of the 

 British Association is opportune. No member of the 



Association who means to see a little of Ireland after the 

 Dublin congress is over should neglect to stow a copy of 

 the book into a corner of his portmanteau. 



Arch. Geikie 



OUR BOOK SHELF 



A Treatise on the Cycloid and all Forms of Cycloidal 

 Curves, and on the Use of such Curves in dealing 

 with the Motiotis of Planets, Comets, &^c., and of 

 Matter projected from the Sun. By Richard A. 

 Proctor. With 161 Illustrations and many Examples. 

 (London : Longmans, 1878.) 



This is a very full book on the curves enumerated ; 

 marked by much elegance in the geometrical portion of 

 the work. It is by far the completest treatise we know, 

 and is likely to take its place as a standard work on the 

 subject. It is marvellous how much can be said about 

 these curves, and one is ready to indorse Chasles' 

 opinion — referring to the cycloid — "Cette courbe mer- 

 veilleuse." Mr. Proctor only slightly glances at the 

 historical side, and merely refers to Pascal's famous 

 questions, a proof of which, we believe, could hardly, if at 

 all, be effected by purely geometrical methods. Use has 

 been made of De Morgan's article on trochoidal curves, 

 the fullest previous exposition of the properties of these 

 curves in relation to epicyclics, and the work, which is 

 admirably printed, has had the advantage of being em- 

 bellished with drawings from Mr. Perigal's well-known 

 mechanically-traced curves (bicircloids). One section is 

 devoted to the analytical equations to the curves, and the 

 last section is a reprint of two papers which have already 

 appeared in the Monthly Notices of the Astronomical 

 Society, entitled "The Graphical Use of Cycloidal Curves 

 to determine (i) the Motion of Planets and Comets, (2) 

 the Motion of Matter projected from the Sun." 



LETTERS TO THE EDITOR 



[The Editor does not hold himself responsible for opinions expressed 

 by his correspondents, l^either can he undertake to return, 

 or to correspond with the writers of, rejected manuscripts. 

 No notice is taken of anonymous communicatitns. 



[The Editor urgently requests correspondents to keep their letters at 

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

 is impossible otherwise to ensure the appearance even of com' 

 munications containing interesting and novel facts,^ 



The Microphone 



The pleasure with which those beautiful discoveries and in<- 

 ventions, the telephone, the phonograph, and the microphone,, 

 have been appreciated by the world, has been unhappily, and L 

 must say I think unnecessarily, marred by one of the most dis- 

 agreeable things that can be thrust on the public — a personal, 

 claim of priority, accompanied by accusations of bad faith, 

 especially when made against any one of whose name and fame 

 the public has come to feel concerned. 



Before troubling the public at all with such a matter, Mr. 

 Edison might surely have reasoned out his claim with Mr. 

 Preece, with whom he had been from the beginning in 

 correspondence, or he might have written immediately 

 to public journals, calmly pointing out the close relation 

 between his own ' ' carbon telephone " and Mr. Hughes' 

 subsequent "microphone." The scientific public could 

 then have calmly judged, and would have felt much interest in 

 judging, how much in common or how much not in common 

 there may be in the physical principles concerned in the two 

 instruments. But by his violent attack in public journals oh 

 Mr. Preece and Mr. Hughes, charging them with ' ' piracy " and 

 " plagiarism," and "abuse of confidence," he has rendered it 

 for the time impossible for either them or others to give any 

 consideration whatever to his claims. Nothing can be more 

 unfounded than the accusations ! Mr. Preece himself gave, at 

 the Plymouth meeting of the British Association last August, a 



