abstracts: topography 423 



In the first place the French have learnt to appreciate the fundamental 

 difference that exists between maps on relatively large scales, such as 

 1 : 20,000, 1 : 10,000, 1 : 1,000 and larger, and maps on relatively small 

 scales, such as 1 : 50,000, 1 : 100,000, 1 : 200,000 and smaller. Upon 

 maps of the former class, most often prepared as a basis for drainage, 

 irrigation and other engineering works, the surface of the land is rendered 

 feature for feature, down to the merest minutiae and the contour lines 

 are frequently run out individually by instrumental survey. " Eye- 

 sketching" plays but an insignificant part in the make-up of such maps, 

 and their main asset lies in their quantitative accuracy. For this reason 

 they are designated "topometric maps" and the art of making them is 

 styled "topometry." 



Maps of the latter kind, on the other hand, by virtue of the limitations 

 set by their scales can give only a generalized protrayal of the land. 

 They are not replicas of the relief in miniature — rather, they partake 

 of the nature of abstracts or condensed statements serving to bring out 

 essentials, at the sacrifice, purposely, of irrelevant detail. Such maps 

 are properly termed "topographic," and the art of making them is called 

 "topography." 



That the two classes of maps grade into each other is evident, at the 

 same time there is great value in drawing the distinction. For, while 

 the preparing of topometric maps involves only surveying and skilled 

 drafting, the preparing of topographic maps is a complicated and subtle 

 art, requiring besides skill in surveying and drafting, trained judgment 

 in the condensing of topographic facts and in their intelligent portrayal 

 in generalized form. Topographic mapping is essentially interpretative 

 and synthetic in its nature, and for its best results demands from the 

 topographic delineator insight into the significance of land forms as well 

 as schooling in the principles of topographic "abstracting." This js a 

 fact that appears to be as yet little appreciated by the geographers, 

 topographers and engineers of this country. In France the desirability 

 of the topographer having an intelligent understanding of the land forms' 

 with which he deals has long been recognized, and the analytical study 

 of those land forms (detail forms mostly) has become known by the 

 name "topology." A two-volume work entitled Topologie, by General 

 Berthaut, Chief of the Service Topographique de l'Armee, recently 

 published, has served to formally usher in the new science. It is to be 

 hoped that some day a similar work may appear in this country for the 

 guidance of American topographers, and if so, that it may go one step 

 further than Berthaut 's treatise and undertake to lay clown the cardinal 



