82 



NA TURE 



{Dec. 3, 1874 



seldom discussed in public, have often been debated when 

 two or three ornithologists are gathered together, are 

 equally left without a word, while a word from Dr. Saxby 

 would have been of the greatest value. Among such is 

 that of the growth of the Puffin's monstrous bill. We 

 have a very well told tale of the author's visit to a Puffin- 

 warren on Hermaness, but it is just such an one as any- 

 body not a naturalist would write, and contains nothing 

 that dozens or scores of British ornithologists did not 

 know before. Again, we may instance the migration of 

 birds. An observer in such a look-out station as the 

 extreme north of Shetland might, one would think, have 

 furnished an infinite number of facts bearing on this im- 

 portant and perplexing question. Dr. Saxby contents 

 himself with telling us when certain species come and 

 go — very valuable information, no doubt, from so com- 

 petent an authority ; but as to the application of such 

 facts, the impression they made as a whole upon his 

 mind, their relation to similar observations in other 

 places, not a word, so far as we can find, is said. Some 

 of the Shetland migrants, we happen from other sources 

 to know, touch the islands as their extreme western, 

 others as their extreme eastern, limit ; but this is all one 

 to our author, who does not seem to care whence the 

 wanderers come or whither they go ; they are regarded 

 by him as " the wind that bloweth where it listeth." 



But enough of this unpleasing task. With the most 

 sincere regret for Dr. Saxby's misfortunes and untimely 

 fate, and a heartfelt sympathy with those who have to 

 mourn his loss, we are compelled to say so much. The 

 old adage de mortiiis is very well in its way, but when -we 

 have him tenned by reviewers " one of the first of our 

 ornithologists," his book " a most valuable contribution 

 to the ornithology of Great Britain," and all the rest of it, 

 we must, if we speak at all, speak the truth. A\'e could 

 count at least a score of British ornithologists who, had 

 their lot been cast in the Shetland Islands, would probably 

 have done much better, and would certainly not have been 

 contented to do so little. His intellectual and scientific 

 capacity is reflected in his editor, who sees in the 

 conductor of a popular magazine one " who has for so 

 many years sat at the focal point" of ornithology — a 

 metaphorical expression to which many meanings might 

 be attached, one of which (though obviously not that of 

 the writer) is that a focus may be found on a blank surface 

 which receives rays of light and does not return them. 

 The "Birds of Shetland" is a book of fair mediocrity. 

 The next faunist, whose work we may be called on to 

 review, will, we hope, take warning by its deficiencies, 

 though for truthful observation — strictly limited, we must 

 say, to observation — he cannot have a better model than 

 Dr. Saxby. More, however, is expected of a faunist in 

 these days. 



MARSH'S ''MAN AND NATURE" 



The Earth as Modified by Hitman Action. A new 

 edition of " Man and Nature." By George P. Marsh. 

 (Sampson Low and Co., 1874) 



AMONG the varied formsofenergy by which the cease- 

 less changes of the earth's surface are produced — 

 subterranean heat, air, rain, frosts, rivers, glaciers, the 

 sea, and the rest — the geologist requires to include as a 



not unimportant agent. Life, both vegetable and animal. 

 Some of the ways in which plants act in augmenting or 

 retarding the operation of the inorganic forces are familiar 

 enough. H ow often, for instance, do we see the walls of a ruin 

 which have been split or cast down by the growing roots 

 of some sapling tree which has found a footing in their 

 masonry. The frosts and storms of winter would have 

 levelled the walls in the end, but their action has been 

 anticipated by the tree. Again, as an everj-day example 

 of the opposite kind of action, we may take the way in 

 which the matted roots of trees which grow along the 

 alluvial margin of a river serve to bind the loose sands 

 or clays of the bank together, and retard the wasting 

 effects of the current. Animals, too, have their own w-ays 

 of eflecting similar results, as every observant rambler in 

 the country can testify. Moles, rabbits, and other bur- 

 rowing animals lay bare the soil to rain and rivulet, and 

 where they cany on their operations in loose materials 

 liable to be dispersed by wmd, as for instance on the 

 sand-dunes by the sea, they may lead to the destruction 

 of much valuable land under the drifting sand which they 

 have uncovered. If we travel into other parts of the 

 globe we find other and better examples, as in the dams 

 of the beaver and the reefs of the coral-polyps. Less 

 easily definable, but probably far more important, are the 

 influences of life upon climate; for although the distri- 

 bution of the fauna and flora of any region is in great 

 measure regulated by climate, it is no less true that 

 climate is modified by the flora, as is shown by the desic- 

 cation of countries which, once green and fertile, have 

 been stripped of their woods. 



So long as man remained in the savage state his influ- 

 ence resembled, and in some respects fell short of, that of 

 the terrestrial animals who were his contemporaries. He 

 felled a tree here and there, and when he had learned the 

 use. of grain, turned moorland into rude fields for culture. 

 But his warfare lay not with the inanimate surface, but 

 mainly with the beasts, fov»ls, and fish on which he chiefly 

 depended for food and clothing. With the slow develop- 

 ment of civilisation his influence as a geological agent 

 has steadily increased, until now it must be ranked in the 

 first class of the forces by which the surface of the land 

 is modified. The time is yet too short during which 

 accurate registers have been kept to admit of any very 

 precise determination of the amount, sometimes even of 

 the nature, of the changes effected by human action. But 

 enough has been recorded to justify the attempt to indi- 

 cate at least the general tendency of man's operations, 

 while at the same time tolerably definite information 

 exists regarding the results of some of his interferences 

 with the ordinary economy of nature. In some respects 

 man's influence is antagonistic to nature's usual modes of 

 working, but of course, viewed broadly, it cannot do more 

 than alter the balance of forces, giving to some a greater 

 and to others a less share of work than in a natural state 

 would be accomplished by them. 



Mr. Marsh's " Man and Nature," published eleven 

 years ago, was the first attempt, at least in English, to 

 take a general view of this subject from a wide basis of 

 reading. A work of research and generalisation from the 

 labours of others rather than of original observation, it 

 called attention to a field of inquiry too little cultivated 

 by geologists. In fact, to its influence we may with pro- 



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