Dr. G. Pilar — On Glacial Epochs. 225 



the destruction of all the larger trees in that island, together with the 

 closing of many historically well-known passes in the Alps, as 

 evidence of recent modifications in the climate, together with various 

 meteorological and botanical observations tending to prove that oscil- 

 lations more or less extensive in the climate of Europe have taken 

 place in comparatively modern times. Dr. Pilar quotes the earlier 

 observations of Charpentier, in which he suggests, as the probable 

 explanation of the former greater extension of the glaciers of the 

 Alps, that in the Quaternary period they stood at a far greater eleva- 

 tion than at present, thus affording a greater gathering-ground for the 

 neve, and that they have subsequently been lowered by subaerial 

 denudation, the detritus forming the great deltas and alluvial valleys 

 of the Ehine, the Ehone, and the Danube, etc. 



The author further gives a resume of the views of Escher von der 

 Linth, Dove, Albert Mousson, Sir John Herschel, Sir W. Thomson, 

 Xiyell, etc. 



Dr. Pilar concludes that any theory which proposes to account for 

 such phenomena by local variation of climate will not avail, and 

 that only cosmical causes can have produced them. He cites the 

 opinions of Godwin-Austen, Eamsay and others, as to the former 

 evidences of glacial action in the New Eed and Permian formations ; 

 he also gives Adhemar's views, formed on Humboldt's observations 

 ■on the alternation of cycles of cold in the northern and southern hemi- 

 spheres caused by the greater or lesser eccentricity of the earth's orbit, 

 as worthy of consideration. But he concludes that Mr. Croll's theory 

 is that which most fully meets the requirements of the case. A rival 

 theory to that of Mr. CroU has been promulgated in Germany by 

 Dr. H. Schmick, which seems to resemble that of Col. Drayson, 

 -quoted by Mr. Belt.^ 



Dr. Schmick believes that the attraction of the sun, alternately 

 exercised on either hemisphere to a greater or less degree, would 

 cause alternations in the volume of the oceans of the globe in the two 

 hemispheres, resulting in periodic floods and glacial epochs. 



One point of interest mentioned by Dr. Pilar is the greater force 

 of the south-west trade-winds, which carry a greater amount of 

 vapour to the Antarctic Continent than the Arctic Sea, thus causing 

 greater relative condensation. 



The chief aim of Dr. Pilar's pamphlet seems to be, first, to give a 

 resume of the various views of writers on climatic variations in the 

 temperature of the globe ; second, to combat the views of Dr. Schmick; 

 and, lastly, to cause those of Mr. Croll to be more generally known 

 on the Continent. 



^ See " An Examination of tlie Theories that have heen proposed to account for 

 the Climate of the Glacial Period," hy Thos. Belt, F.G-.S., Quart. Jonrn. Science, 

 1874, No. xliv. See also H. Woodward's Presidential Address to the Geologists' 

 Association, Nov. 1874. And Anniversary Address by Mr. John Evans, F.E-.S., 

 President Geol. Soc, London, 18th Feb., 1876. 



DECADE II.— VOL. III. — NO. V. 15 



