256 



SCIENCE. 



[Vol. XII. No. 304 



one map a much wider field, from which all minor features had 

 been of necessity excluded. 



The value and importance of these topographical maps for mili- 

 tary purposes were brought into great prominence during the Na- 

 poleonic wars. Napoleon, recognizing their importance and value, 

 gave a powerful stimulus to military surveying. He also clearly 

 perceived the value and importance of representing the hitherto un- 

 represented element of surface form, and to him is said to be due 

 the introduction on topographic maps of a representation of the re- 

 lief. Then arose systems of different kinds for showing form as 

 well as feature, and thereafter the exhibition of the relief came to 

 be regarded as essential to a topographic map. Thus the word 

 ' topography ' underwent a change, an extension of meaning, — an 

 extension to be followed later by a restriction of meaning. When 

 usage had established that by ' topography ' both the form and the 

 features of the surface were implied, then the need of distinct terms 

 expressing these two elements arose. Very soon we find ' topog- 

 raphy ' being unconsciously used to imply surface form alone, and 

 this unconscious use has now become conscious and established. 

 A new word or phrase is therefore needed to express the features, 

 but we have no such term. Thus at first ' topography ' relates to 

 surface features, and chiefly artificial ones, villages, roads, cities, 

 orchards, walls, gardens, buildings of various sorts, etc., and all 

 water bodies ; later the term is expanded to mean all these, and in 

 addition the surface form ; and finally, before losing this extended 

 signification, it is restricted, and used to signify surface form only. 

 Primarily it related to features only : it is now used to relate to 

 surface form. At the same time the earlier, but not earliest, use 

 survives, and is used to imply both forms and features : hence have 

 arisen apparent disagreement and discussion from confusion of 

 meaning of the word. 



The features exhibited on maps called topographic may be con- 

 veniently grouped into three heads : (<;) the water features, — ponds, 

 streams, lakes, etc.; (b) the surface form, — hills, valleys, plains, 

 etc. ; {c) the features constructed by man, — cities, villages, roads, 

 etc. ; and, if need be, general terms might be coined to express 

 these three classes of phenomena. 



The description of water features would naturally be the ' hydrog- 

 raphy ; ' the description of the form, ' cidography ; ' and the de- 

 scription of the constructed features, the ' tectography.' 



This seeming long digression into the meaning of the term 

 ' topography ' is only seeming. As a piece of word-history, it is 

 not pertinent ; but, as a prerequisite to a clearly defined comprehen- 

 sion of the subject rather than the word, it is of first importance. 

 The proper conduct of a topographic survey requires a clear under- 

 standing of what it is, what it is not, and why it is made. What, 

 then, is the object and purpose of topographical surveys .' 



The object and purpose of topographical surveys is, as I con- 

 ceive it, the production of topographical maps, — a definition 

 which, without a definition of ' topographical map,' appears mean- 

 ingless. But even before defining that particular species of map 

 called ' topographic,' it appears that the aim of the survey is solely 

 to produce a map. Its purpose is not the erection or refined loca- 

 tion of monuments, nor the tracing of boundary-lines, public or 

 private, nor the establishment of bench-marks. The doing or not 

 doing of these things does not destroy the essential character of 

 the survey, which is the production of a topographical map, — a 

 map which shall exhibit, with an accuracy and detail sufficient for 

 all general purposes, the relation of the features of a country to one 

 another, and to the form of the surface upon which they are. The 

 erection, description, and location of boundary-marks is the special 

 work of the boundary survey ; the erection, description, and precise 

 determination of bench-marks — as permanent reference-marks — 

 is the work of the geodetic survey ; while the less precise determi- 

 nation of many unmarked stations for temporary use in map-making 

 is the work of the topographic survey. 



The topographic survey, like all others in our first category, — 

 the geodetic, geologic, etc., — is not special, but general. It is not 

 made for the purpose of constructing railroads, though a very valu- 

 able aid in projecting railroads. It is not made for the specific 

 purpose of reclaiming swamp-land, or arid land, or flood-plain land ; 

 iDUt it furnishes general information essential to a preliminary study 

 and plan for improvement. It is not made specifically for war 



purposes, though useful for such purposes, and serving as a basis 

 for special surveys for military purposes. It is not made for any 

 one specific purpose, any more than a jack-knife is ; but, hke the 

 jack-knife, it serves many purposes, even though it serve some of 

 them less well than a special tool constructed for the special pur- 

 pose. 



The outcome of a topographic survey, being a topographic map, 

 should be judged by the map ; and the map, being for general pur- 

 poses, should be judged by the manner in which it serves the gen- 

 eral rather than the special purpose. And, further, of two maps, 

 or works of any kind, made for the same purpose, and serving that 

 purpose equally well, that one is best which is the cheapest, — a 

 well-recognized principle, especially among engineers. 



In the conduct of a topographical survey, one most important 

 question must be decided in advance ; viz., the scale to be adopted. 

 Almost all questions of detail hinge upon this. Large-scale maps 

 permit the exhibition of many and small details, and of the relation 

 of objects to one another, with greater precision than small-scale 

 maps, just as a high-power microscope reveals details not to be 

 seen with lower power. For certain purposes microscopes of only 

 very low power serve best ; for others, those of moderate power ; 

 and for still others and special purposes very high powers serve 

 best. So, also, for many purposes maps of small scale are desir- 

 able ; for others, maps of moderate scale ; while for other and 

 special purposes maps of very large scale serve best. What the 

 best scale is for general purposes has been the subject of very ani- 

 mated and even heated discussion in European countries, particu- 

 larly in England, where, in connection with the Ordnance Survey, 

 the " battle of the scales " was fought with great vigor some thirty- 

 five years ago. And, as is apt to be the case in such controver- 

 sies, there were good reasons on both sides, — good reasons for 

 making the scales large, and other good reasons for making them 

 small. The best scale to adopt, therefore, all things considered, 

 was a matter of judgment, and hence the diverse views. 



There seems to be no better way of getting at general opinion 

 upon the subject of scales than to see what, as a result of study and 

 experience, various map-making nations have adopted. 



The following table, therefore, is presented, showing the scales 

 upon which fourteen foreign states are constructing, or have con- 

 structed, general topographic maps of their areas : — 



Publication Scales of Stand 



■ Foreign States. 



Norway. . 

 Portugal . 



Austro-Hungary i : 75,000 



Great Britain 1:63,360 



Sweden i : 50,000 and 



Italy i: 50,000 



Spain ? 1:50,000 



Denmark i : 40,000 and ; 



Switzerland i : 25,000 and i 



Belgium i : 20,000 and 



These scales all cluster around one mile to an inch. In coun- 

 tries of small extent and of dense population the scales are larger. 

 In countries of larger extent and sparser population the scales are 

 smaller. The lesson taught by this table is conceived to be of 

 great value in determining the scale or scales that should be 

 adopted for a general topographical map of the United States. 



A statement recently published, that " maps upon a scale of less 

 than two inches to one mile are of but little use for definite pur- 

 poses," is therefore an individual opinion, which contrasts with the 

 general opinion in such matters, as inferred from the scale in use 

 by nations conducting topographic surveys. 



Topographic surveys may be conveniently classified under two 

 heads having reference to their purpose. If made for general use 

 and information, they constitute the ordinary or usual topographic 

 survey ; while, if made for war purposes, they are military topo- 

 graphic surveys. Most of the great militant nations make special 

 surveys and maps, which are unpublished, and are kept secret in 

 the archives of the War Department. The changes in the mode of 

 conducting wars incident to improvement in fire-arms and explo- 

 sives necessitate corresponding changes in the military maps. 



