254 National Geographic Magazine. 



TOPOGRAPHIC MODELS. 



By Cosmos Mindeleff. 



Op the many methods by which it has been sought to represent 

 the relief of a country or district, only two have been at all widely 

 used. These methods are, in the order of their development, by 

 hachured and by contoured maps. Both have advantages and 

 both have serious disadvantages. Without entering into the 

 controversy that is even yet raging over the relative merits of 

 the two systems, some slight notice of what each claims to 

 accomplish is necessary. 



The representation of relief by hachures is a graphic system, 

 and in the best examples we have is an attempt to show, upon a 

 plane surface, the actual appearance of a given area under given 

 conditions of lighting, — as in the Dufour map of the Alps. Of 

 course certain details that would really disapjDear if the assumed 

 conditions were actual ones, must be shown upon the map, — so 

 that it is, after all, but a conventional representation. The very 

 best examples are, for this and other reasons, unsatisfactory, and 

 far more so is this the case in the vastly larger class of medium 

 grade and poor work. 



The contour system represents i-elief by a series of lines, each 

 of which is, at every point throughout its length, at a certain 

 stated elevation above sea-level, or some other datum-plane ; in 

 other words, each contour line represents what would be the 

 water's edge, if the sea were to rise to that elevation. It pos- 

 sesses the advantage of great clearness, but fails to a large degree 

 in the representation of surface detail; moreover, one must have 

 considerable knowledge of topography, in order to read the map 

 correctly.* 



To those who must give first place to the quantity of relief 

 rather than the quality, as, for example, the geologist or the 

 engineer, a contoured map is now considered essential. On the 

 other hand, where quality of relief is the prime consideration 

 and the quantity a secondary one, as, for example, for the use of 

 the army, a hachured map is considered the best. The method 



* For specimens of representation of the same subject on different 

 scales, in both the hachure and contour systems, see plate from " Enth- 

 ofler's Topographical Atlas." 



