NATURE 



[November i, 1900 



acorns. Both these oaks are usually grown isolated in 

 vineyards for their cork. Quercus Tozza is restricted to 

 the south-west of France, where extensive coppices of it 

 are grown for fuel. Hornbeam is abundant in the north- 

 east, chiefly in coppice-with-standards ; its abundance in 

 Epping Forest probably dates from the time when Eng- 

 land was connected by land with the Continent. Other 

 species of forest trees, such as ash, alder, sweet-chestnut, 

 sycamore, willows, poplars, birch, lime, elms, &c., are 

 either confined to special soils over small areas, or 

 disseminated in forests of the principal species that have 

 been already mentioned. Maps are given in the text- 

 book showing the geographical distribution of the 

 principal trees. 



There is an excellent chapter on the action of trees on 

 one another, and on the value of shade-bearing species, 

 such as beech, as auxiliaries to the more valuable light- 

 demanding trees, such as the pedunculate and sessile 

 oaks, the former being chiefly grown in the lowlands on 

 deep, moist or even wet soils, as standards over coppice, 

 and the latter with beech in high forests on the hills. 

 Both these oaks, as well as the holm oak, are also exten- 

 sively grown in coppice woods, chiefly for their bark, as 

 tanning material. 



A good account is given of the nature of forest soil, 

 and the necessity of preserving the dead leaves to form 

 humus is strongly insisted on. It has been proved by 

 Grandeau and Henry, two of the Nancy professors, 

 that besides serving as food for earthworms and other 

 organisms, the activity of which keeps the soil porous, 

 friable and superficially rich in nutritive mineral matter, 

 dead leaves fix atmospheric nitrogen to the extent of 

 12-20 lbs. per acre annually. To deprive the forest of 

 its dead leaves is like robbing a farm of its dung. 



The evolution of a crop of trees by natural regeneration 

 is well described, the account of coppice-with-standards 

 being probably more complete than in any other text- 

 book. The cultural methods to be followed when once 

 the new crop is established are also well explained and 

 chiefly consist of cleanings and thinnings. The authors 

 are strongly opposed to the pruning of forest trees, and 

 consider that drainage is very rarely required. Their 

 remarks on these points should be read. Among 

 sylvicultural systems yielding even-aged high forest 

 {futate regidiere\ the clear-cutting system i^procede par 

 coupe unique)^ which is so extensively followed in parts of 

 Germany for crops of spruce or red pine, is employed in 

 France only for maritime and Aleppo pines. The cones 

 of the pine trees adjoining a clearing produce abun- 

 dance of seed, which at once stock the ground, provided 

 the felled material is rapidly removed, and the seedlings 

 of these trees are so vigorous and hardy against drought, 

 that they soon dominate the mass of bushes and weeds 

 springing up around them. 



The system under which a mature crop is gradually 

 removed {procMe par coupe sticcessive), termed by Dr. 

 Schlich shelter-wood compartment system, is that com- 

 monly employed in French high forests. It gives 

 admirable results in oak and beech woods, but its appli- 

 cation to silver-fir is not so successful, as silver-fir grows 

 better when the larger trees are surrounded by an 

 irregular undergrowth of beech and silver-fir. 

 . The selection system {jardinage) similar to that em- 

 . NO. 1618, VOL. 63] 



ployed in the Chiltern Hills for beech, is much used in 

 France for silver-fir, chiefly in communal and private 

 forests, and in State forests in mountainous districts, 

 where it affords the best protection against denudation 

 of the slopes. 



About 70 pages of the book are devoted to an accoun 

 of possible injuries to the forest by men, animals, plants 

 and meteoric influences. This really constitutes the sub- 

 ject of Forest Protection, and is usually dealt with apart 

 from sylviculture in German and English forestry text- 

 books. One hundred and sixty pages at the end of the 

 book treats of artificial reproduction, and resemble the 

 account of sowing and planting usually given in other 

 good sylvicultural works. This part of the book termin- 

 ates with an account of exotic trees, the introduction of 

 which is not viewed in France with nearly so much 

 interest as with us, although the subject is very judiciously 

 treated in the present volume. 



The book is profusely illustrated by reproductions of 

 photographs chiefly taken by Nancy students during 

 their summer tour ; it forms a highly valuable contribu- 

 tion to forestry literature, and is certainly the best account 

 of French sylviculture that has yet appeared. There is a 

 good table of contents, but no index, the omission of 

 which is to be regretted. W. R. Fisher. 



TOPOGRAPHIC SURVEYING. 

 Topographic Surveying. By Herbert M. Wilson. Pp. 

 884. (New York : Wiley and Sons. London : Chap- 

 man and Hall, 1900.) 



MR. WILSON'S book is comprehensive, clear and 

 well illustrated, and contains much information 

 of practical use to the surveyor and explorer, which is 

 not usually found in works on surveying and map-making. 

 Its author is a member of the staff" of the United States 

 Geological Survey, and his remarks on the methods and 

 processes of that Survey are therefore of special interest. 

 The Geological — which is virtually a topographical — 

 Survey of the United States is a work of great magni 

 tude, and the manner in which the staff" engaged upon it 

 have met the numerous technical, transport and othe 

 difficulties that have arisen during its progress is most 

 interesting. It was laid down as a general principle 

 that no part of the country should be surveyed in greater 

 detail, or at greater cost, than was necessary for the 

 purposes which the resultant map was intended to sub- 

 serve. This involved a rapid and economical survey of 

 a vast extent of country within reasonable limits of 

 error. The method adopted 



" consists of a combination of trigonometric, traverse 

 and hypsometric surveying to supply the controlling 

 skeleton, supplemented by the ' sketching in ' of contour 

 lines and details by a trained topographer. In this 

 method the contour lines are never actually run out, nor 

 is the country actually cross-sectioned." 



The instruments used vary with the nature of the 

 country. For geodetic work, a combination transit and 

 zenith telescope of special pattern (p. 726) has been found 

 most convenient. Primary bases are measured with steel 

 tapes, with an average probable error of 1/300,000, in 

 from seven to ten days, at a cost of 20/. to 40/. ; whilst 

 the bases of the U.S. Coast and Geodetical Survey have 



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