156 Reviews. [Jan., 



men not intending to practise the medical art to study its pages. It 

 is a mistake to suppose that the laws of life are alone of practical in- 

 terest to the medical practitioner. There is no man that has a body 

 to preserve from disease and save from a premature death that is not 

 interested in the study of the principles of Human Physiology. 



MAN AND NATUEE* 



The influence of man, whether civilized or uncivilized, on the face of 

 nature, is a subject that has not failed to attract the attention of phy- 

 sical geographers ; but the facts of history, though often alluded to, 

 have not yet been collected and brought into a single volume before 

 the publication of the present work. Judging from the useful list of 

 references at the commencement, the author has laboured very con- 

 scientiously ; and the result, although rather heavy reading, is an 

 interesting collection of valuable records. 



Man produces effects on the earth's surface, both directly and in- 

 directly, and these effects are sometimes conservative, but for the most 

 part destructive, tending to derange and interfere with the balance of 

 nature. That man's influence, especially in a civilized state, is 

 exceedingly potent, there can be no doubt ; and it is shown in a very 

 striking manner in relation to the organic world. Thus millions of 

 wild cattle are wantonly destroyed in South America, for the sake of 

 their hides and horns ; tens of thousands of elephants, for their tusks ; 

 and thousands of ostriches, for their wing feathers. And, far above 

 and beyond all these destructions, there is the cutting down of timber, 

 which has been carried to so great an extent in Europe, and even in 

 North America, as to interfere greatly with climate, and change the 

 conditions of the atmosphere. There can be no doubt that, in South- 

 Eastern Europe, where forests no longer remain, the once well-wooded 

 and humid hills have been turned to ridges of hard rock, without a 

 particle of soil. Even within the historic period, these naked rocks 

 were, to a large extent, clothed with forests. The change that has 

 taken place is due to the continued residence of man, and it is one 

 of which the magnitude and importance are by no means duly con- 

 sidered. 



The removal of woods and forests seems to be one of the first 

 results of civilization. But the effect of this removal is rapid and 

 cumulative, and seems generally injurious. First, the earth, deprived 

 of its green and living clothing, radiates heat much more rapidly 

 under a clear sky at night, and receives much more heat from the sun 

 by day. The climate thus becomes excessive. Bleak winds sweep 

 over the cleared surface ; and when rain falls, it is rapidly carried off, 

 instead of being long retained on the surface, and carries with it 



* ' Man and Nature ; or, Physical Geography as modified by Human Action." 

 By George P. Marsh. London : Sampson Low, Son, and Marston, 1864. 8vo. 

 pp. 560. 



