Topographic Models. '^bl 



the work any ordinarily intelligent person can do. A model may 

 be as accurate as the map from which it is made, every contour 

 may be placed exactly where it belongs, and yet the resulting 

 model may be, — indeed, often is — " flat," expressionless, and un- 

 satisfactory. Every topographer in drawing his map is compelled 

 to generalize more or less, and it is fortunate for the map if this 

 be done in the field instead of in the draughtsman's oflfice. But 

 topographers difl[er among themselves: there may be, and often 

 is, considerable difference in two maps of the same region made 

 by diffei'ent men; in other words, the "personal equation" is a 

 larger element in a map than is usually supposed. This being 

 the case, there is something more required in a modeler than the 

 mere transferring of the matter in the map, — giving it three 

 dimensions instead of two: he must supply through his special 

 knowledge of the region (or, failing that through his general 

 knowledge) certain characteristics that do not appear upon the 

 map, and undo, so far as it is necessary, certain generalizations of 

 the topographer and draughtsman. This artistic or technical 

 skill required correctly to represent the individuality of a given 

 district is especially important in the modeler; it is more impor- 

 tant, perhaps, in small-scale maps of large districts than in large- 

 scale maps of small ones, — for in the latter the generalizing pro- 

 cess has not been carried so far, and the smaller interval of the 

 contour lines preserves much of the detail. 



The methods by which relief maps are made have always re- 

 ceived more attention than would, at first sight, appear to be 

 their proper proportion. It may be due, however, to the difficulty 

 of applying any test to determine the accuracy of the finished 

 model, and perhaps also to the general impression that any one 

 can make a relief map, —and so he can, though of course there 

 Avill be a wide difference in the value of the results. Some, 

 indeed, have devoted their attention to methods exclusively, 

 letting the result take care of itself, — and the models show it. 

 There is no more reason why a modeler should tie himself down 

 to one method of work, than that a water-colorist, or a chemist, 

 or anyone engaged in technical work, should do so; though in 

 some cases he might be required, as the chemist is, to show his 

 methods as well as his results. 



One of the earliest methods, with any pretension to what we 

 may term mechanical control, is that described by the Messrs, 

 Harden in a paper on " The construction of maps in relief," read 



