November i, 1900] 



NATURE 



a probable error of 1/1,000,000 to 1/1,500,000, take from 

 two to six months to measure, and cost from 500/. 

 to 2600/. The observations for the primary triangu- 

 lation are made with an 8-inch direction theodolite, the 

 average rate and cost being six stations per month and 

 3J. ^d. per square mile, and the average probable error of 

 the triangulation 1/40,000. The averages of the Geodetic 

 Survey are three-fourths of a station per month, from £2 

 to ^6 per square mile and the probable error 1/150,000. 

 For filling in the detail the essential instruments are the 

 plane-table and telescopic alidade (p. 156). The hori- 

 zontal distances are obtained, according to circumstances, 

 by triangulation with the plane-table, by stadia and 

 odometer measurements, by chaining, and by pacing. 

 The altitudes are dependent upon primary lines of levels 

 run with a precise spirit-level (p. 328), and having a 

 probable error in feet = "02 ^ distance in miles ; on 

 angles of elevation and depression at the principal trig- 

 onometrical stations, on secondary lines of spirit-levels 

 and on aneroid observations. The topographical features 

 are represented on the map by contour lines sketched by 

 eye with the assistance of an aneroid, and great im- 

 portance is attached to the quality of the sketching. 

 This depends upon the artistic and practical skill of the 

 topographer, or upon his ability to make correct 

 generalisations, and decide upon the amount of 

 detail which should be omitted or preserved so 

 as to bring out, on the selected scale, the 

 predominant features of the country surveyed. In this 

 work, as the author justly remarks, great proficiency 

 " can only be attained after years of experience." He 

 also rightly holds that the topographer should have a 

 sufficient knowledge of geology and physiography, or of 

 the " origin and development of topographic forms," to 

 enable him to appreciate the features which he is sketch- 

 ing and to represent them intelligently on his sketch. 



Mr. Wilson's book is, however, very far from being a 

 simple manual for the use of the Geological Survey. It 

 deals with every description of survey, and treats each 

 fully. Part i. contains much useful information on the 

 different classes of survey. An interesting description 

 is given of the survey of Baltimore on a scale of 1/2400, 

 which corresponds nearly to the 25-inch scale of the 

 Ordnance Survey ; but if the figures given in the table, 

 p. 107 (Baltimore 814/. per square mile, Ordnance 

 Survey 59/. )» are correct, the cost would be considered 

 prohibitive in «this country. The remarks on geographic 

 and exploratory surveys are good, and Mr. Johnson's 

 excellent plane-table sketch, which is given as a 

 specimen of an exploratory survey (p. 91), may well 

 serve as a model for sketchers. Military surveys are 

 correctly defined as having for their object "the repre- 

 sentation of the natural and artificial features of the 

 country with the maximum exactitude consistent with 

 the greatest rapidity of execution." The concluding 

 chapter is a well illustrated memoir on the relations of 

 geology to topography, and on ' earth sculpture,' or the 

 constructive and destructive processes by which existing 

 topographical features have been formed. The import- 

 ance of a knowledge of these subjects to the topographer 

 and cartographer is clearly pointed out. A valuable 

 addition to the chapter is a glossary of all geographical 

 and topographical descriptive terms in common use in 

 NO. 1618. VOL. 63] 



the United States, which, pending the compilation of a 

 similar list for the United Kingdom, will be found useful 

 in this country. 



In Part ii. the instruments^ and methods employed 

 in the measurement of horizontal distances and in plane 

 surveying are clearly described and explained. Chapters 

 vii. and viii. on plane-tables and alidades, and chapters 

 xii. and xiii. on stadia and angular tachymetry, deserve 

 the attention of surveyors in England, where stadia 

 measurements, which give results over rough ground as 

 good as those with the chain, are little known. In another 

 chapter the author describes photo-surveying methods, 

 which are much in favour in Canada, and points out 

 their limitations and the conditions under which they 

 can be advantageously employed. Part iii. deals with 

 instruments and methods for the determination of 

 altitudes. The American spirit levels and levelling staves 

 are of better pattern than those in use on our Ordnance 

 Survey, and the accuracy of the principal lines of levels 

 is greater than that of the similar lines in Great 

 Britain. In Part iv. the author explains the various 

 kinds of map projections, the methods of repre- 

 senting hill features and the construction of relief 

 maps. He very rightly lays down that the carto- 

 grapher should be "possessed of such actual know- 

 ledge of map-making as is .only gained by practical ex- 

 perience in field-surveying," and that the topographer 

 should have a general knowledge of projections and map 

 construction. The difference between the principal 

 methods of representing ground is well brought out ; that 

 by hachures is happily characterised as " a graphic 

 system with a conventional element," and that by con- 

 tours at close intervals as " a conventional system with 

 a graphic element." Wax and clay mixed with glycerine 

 are considered the best materials for modelling, and it is 

 pointed out that a modeller should have a good know- 

 ledge of topography. Parts v. and vi., " Terrestrial 

 Geodesy " and " Geodetic Astronomy," are clearly 

 written and well supplied with tables ; and the latter 

 contains a chapter on " Photographic Longitudes." In 

 Part vii. the surveyor in unsettled country will find 

 many excellent hints as to camp stores and equipment, 

 pack transport, medicines, clothing and photography. 



In conclusion, it may be added that the book contains 

 884 pages, 62 tables of various kinds, 205 excellent illus- 

 trations, and a most useful index. It would in some 

 respects have been more convenient if it had been pub- 

 lished in two volumes. C. W. W. 



THE ETHNOGRAPHY OF BRITISH 

 COLUMBIA. 

 Memoirs of the American Museum of Natural History. 

 Vol. II. Anthropology, i. The Jesup North Pacific 

 Expedition. iv. The Thompson Indians of British 

 Columbia. By James Teit. Edited by Franz Boas. 

 (1900.) 



IMPORTANT results were looked for from the Jesup 

 North Pacific Expedition, and the realisation has 

 not belied the expectation. Thanks to the intimate 

 knowledge of Mr. James Teit of their language, customs 

 and beliefs, we now have a remarkably detailed and 

 complete description of the Upper and Lower Thompson 



