April 1, 1897.] 



KNOWLEDGE, 



95 



formed of Silurian rocks, with a large amount of intrusive 

 Igneous masses ; but the rocks are for the most part not 

 metamorphosed like their representatives of the Gram- 

 pians, and so give smoother features with grassy hill- 

 slopes. The Igneous rocks have in many places been out- 

 poured as lava over the sedimentary strata, and resisting 

 denudation by their superior hardness now form hilltops, 

 and so preserve the softer rocks below. The Silurian 

 strata dip northwards under the Old Eed Sandstone and 

 Carboniferous rocks, to reappear in the Grampians highly 

 metamorphosed. As the Carboniferous beds have once 

 extended over the whole area from the Lanarkshire coal- 

 field to the Cheviots, the elevation of Scotland's southern 

 mountains must have been subsequent to the Carboniferous 

 period. 



IRELAND AND THE ISLE OF MAN. 



When St. George's Channel is crossed other most inter- 

 esting groups of mountains present themselves in Ireland. 

 These surround the great central plain of the island of 

 Carboniferous Limestone. 



The highest mountains of Ireland are in the south- 

 western group, where in the Killarney district one of the 

 peaks of Macgillicuddy's Reeks, Carntual, towers to three 

 thousand four hundred and fourteen feet above sea-level. 

 This portion of Ireland is formed by Devonian and Carbo- 

 niferous rocks in a succession of parallel anticlinal and 

 synclinal folds, the Devonians forming the anticlinals, 

 which are elevations that to the west project into the sea 

 and form the bold and picturesque headlands of the South- 

 AVest of Ireland, while the Carboniferous rocks in narrower 

 bands occupy the synclinal valleys which terminate sea- 

 wards in bays and indentations of the coast. As there are 

 no remains of later strata here it is necessary to look to 

 the eastward prolongation of these flexures in England in 

 determining the age of the upheavals, and there it is found 

 that horizontal Triassic rocks rest upon highly inclined 

 Carboniferous strata, which indicates an elevation of the 

 50uth-western mountains of Ireland between the Carboni- 

 ferous and the Triassic periods. 



In the South-East of Ireland a group of mountains rises, 

 in Lugnaquilla, to three thousand and thirty-nine feet, and 

 consists of ranges having a south-west and north-east 

 general direction. They are formed of Cambrian and 

 Lower Silurian rock3,with great masses of intrusive granites 

 and intrusive Igneous rocks. The granites form a great 

 mountain mass extending south-westwards fromDublinBay, 

 and are possibly mainly metamorphic. They are, however, 

 confined to the Silurian area. As the Old Red Sandstone 

 has been found to overlie the Silurian rocks, and then 

 eroded granite — which, from its importance in the area, 

 must be associated with the general upheaval — it may be 

 concluded that this upheaval was pre-Devonian, but sub- 

 sequent to, or at the close of, the Lower Silurian period. 



Passing to the north, there is a remarkable group of 

 mountains, which give a summit elevation in Slieve 

 Donard of two thousand seven hundred and ninety-six 

 feet. These mountains form three ranges, the ilourne, 

 the Carlingford, and the Slieve Croob Mountains, of which 

 the first is the highest. They consist chiefly of metamor- 

 phosed and Igneous rocks, granites, syenites, dolerites, 

 etc., and may be regarded as portions of the base of a 

 great volcano. From their containing altered Carboniferous 

 Limestone masses, the age of the rocks is certainly post- 

 Carboniferous ; and from their dissimilarity to the Tertiary 

 volcanic rocks of Antrim, they are probably much older 

 than the Tertiary period. 



The north-western mountains of Ireland, with which 

 may be associated those in the extreme west, are un- 

 doubtedly the oldest mountains of the island. They rise 



to a summit elevation, in Muilrea, of two thousand sis 

 hundred and thirty-eight feet above the level of the sea. 

 They consist of metamorphosed and highly contorted 

 Lower Silurian rocks, with Upper Silurian strata un- 

 conformable and unaltered, and containing beds of 

 conglomerates ; and in Donegal, as before mentioned, a 

 great granitic mass ranges from south-west to north-east. 

 The stratigraphical evidence indicates an upheaval here 

 at the commencement of Upper Silurian times. 



The mountains of the Isle of Man are very lofty 

 elevations for the size of the island, attaining in Snafell to 

 two thousand and thirty-four feet above the level of the 

 sea. They are formed of schistose rocks of the same 

 character and age as the Skiddaw Slates of Cumberland, 

 which encircle and overlie masses of granites. These 

 Lower Silurian rocks are upturned, and on their denuded 

 edges repose conglomerates which have now been de- 

 termined to be the lowermost beds of the Carboniferous 

 series, though once thought to be of Devonian age. 

 The elevation of the mountains, it is therefore evident, 

 had taken place before the Carboniferous rocks were 

 deposited. 



Noti(t9 of Boolts. 



The Life and Work of Charles Pritchard, Sarilian Professor 

 of Astronomy in the Unirersitij of Oxford. (Seeley.) 10s. 6i. 

 Many hands have contributed to the portraiture in this 

 work, and it was a wise arrangement, for Prof. 

 Pritchard's life was a long one, and of such varied activity 

 that a single biographer could scarcely have done justice 

 to its very difl'erent aspects. " He really lived the lives and 

 earned the fame of two or three ordinary men." The 

 book has been in part written by Miss Ada Pritchard, and 

 she has entrusted the first chapter on his early life to Prof. 

 Pritchard's niece, Mrs. Ogier Ward, and the little details 

 which the latter gives of his ancestry and early upbringing 

 aft'ord a clue to much that otherwise would be incompre- 

 hensible in his character. It enables us to understand 

 how a man " bristling at all points with asperities " could 

 yet not only win general respect, but exercise a positive 

 fascination. It is, perhaps, as a schoolmaster that Prit- 

 chard was seen at his best. His originality and keen 

 discernment showed here to the greatest advantage, and 

 he became not merely one of the pioneers of modern edu- 

 cation, but apprehended and avoided educational pitfalls 

 which are even yet too common. In this section the editor 

 has wisely allowed her father for the most part to speak 

 for himself, the second chapter being drawn from his auto- 

 biographical pamphlet, " Annals of our School Life." 

 Here he lays it down as a maxim " that the main intention 

 of early education should be the development of the Imhit 

 of thinkiihi, and the exhibition of the right mode of setting 

 about it." 



His second greit rule was, that the time for the multi- 

 farious instruction required for his full scheme of education 

 was to be found " in the systematic accumulation of small 

 increments : but it must be systematic, and, beyond all, it 

 must be sincere and impartial." It was the same principle 

 of steady and systematic accumulation which enabled him 

 when director of the University Observatory at Oxford to 

 accomplish in the last years of his life more than many 

 men have done in a whole lifetime of spasmodic devotion 

 to the science. Thus the completion of more than seventy 

 thousand careful measures of photographs of stars, he says, 

 might be accomplished by equal daily instalments, without 

 any stress of mind, in less than a year. 



His successor at Oxford, Prof. Turner, emphasizes Prof. 



