308 



SCIENCE. 



[Vol. XIII. No. 324 



taking in the preparation of working maps of their territories, and 

 the extensive surveys that have been authorized by the general gov- 

 ernment. Any thing, therefore, that will tend to bring about a bet- 

 ter understanding of general terms should be hailed as a step in 

 the right direction. Mr. Baker presents one view of the subject in 

 a forcible manner, but it seems to me far from satisfactory. 



The title of the paper fairly justifies the impression that the au- 

 thor intended to classify surveys which result from the practical 

 application of the science and art of surveying ; and, indeed, the 

 subjects enumerated in the second and third of his "great divis- 

 ions " bear out the inference. In the " first division," however, 

 which includes all surveys for general purposes in its broad scope, 

 he fails to mention many kinds which he might include, unless he 

 is willing to restrict the word " survey " to work related to what the 

 Germans would call Vermesstings Kitnde. Why include geological 

 and agricultural surveys, and omit statistical, ornithological, and 

 botanical surveys, not to mention many others .' 



The geologist doubtless needs maps on which to exhibit some of 

 the results of his geological explorations, but the science of geology 

 and that of surveying can hardly be related by merely putting the 

 words in juxtaposition. It must ever remain a thankless task to 

 classify heterogeneous subjects whose kinship is due merely to the 

 use of the word " survey " in a metaphorical or general sense, 

 rather than in the precise and technical one in which it is used 

 when applied to the second and third divisions. 



But Mr. Baker does not uphold the classification he has offered 

 any further than to maintain that it will answer his purpose quite 

 as well as many others that could be made ; and we might there- 

 fore let it pass had he not advanced a principle for its construction 

 that would tend to endless difficulties should it be universally 

 adopted. 



That " surveys must be of various kinds, because they are made 

 to serve various purposes : a classification of kinds is, then, a clas- 

 sification by purposes," — I believe to be a fundamental error. 

 Nor is it strengthened by the grouping into three great divisions, — 

 "information," "boundary," and "improvement" surveys; or, as 

 he expresses their equivalents, " general," " jurisdictional," and 

 " construction " purposes ; or the subsequent definition that " the 

 general study of the earth is the object and purpose of information 

 surveys." Strictly speaking, all surveys are for information, and 

 therefore the three great divisions could with propriety be consoli- 

 dated into one. It is only through the definition, " the study of the 

 earth," that the " divisions " are plausible. Admit that a survey 

 may be useful for many purposes, and they are no longer tenable. 

 There are but few surveys of mensuration that have been insti- 

 tuted primarily for the purpose of acquiring information for " the 

 study of the earth," while all contribute to this end. For many 

 years past, since the art of surveying has been recognized as a 

 science, surveys have been classed under designations that seem 

 to me to admit of little improvement, — from "geodesy" we 

 have "geodetic" (measurement of the earth); from "topogra- 

 phy," " topographic " (measurement of the land areas) ; and 

 from " hydrography," " hydrographic " (the water areas). All 

 surveys of mensuration are included in these three, either directly 

 or in combination with one another. A geodetic survey has a sin- 

 gle purpose primarily, but it may also be the basis for all other 

 surveys. Topographic and hydrographic surveys maybe executed 

 independently of the geodetic, or may be based upon it. They 

 may also be conducted on the principle of the Coast Survey, based 

 upon a triangulation not always of geodetic value. Such a work 

 has frequently been designated a " trigonometrical survey," imply- 

 ing areas of land, water, or both, in which the distances and direc- 

 tions are controlled by a triangulation. 



There is a second class of surveys that consist largely of explo- 

 rations, such as geological, agricultural, botanical, magnetic, etc., 

 that require surveys of mensuration in greater or less detail for their 

 comprehensive elucidation. But the mensuration does not give 

 them their value ; and it is desirable, therefore, that they should 

 not be classed with work of that description. Aside from the fact 

 that they are so comprehensive, a classification by themselves seems 

 essential. 



Surveys of mensuration may be divided into many subordinate 

 classes, but they do not necessarily lose their general distinctive char- 



acter in the process of division. Surveys for railroads, canals, or any 

 works of construction on the land, are still topographic surveys. 

 For many works of construction, the surveys must be of the most 

 detailed character, and their execution is topographic work of the 

 highest order. A great deal of confusion has undoubtedly arisen 

 from the inadvertent use of the word " topography," restricting it 

 to a description of the irregularities or relief of the earth's surface. 

 Originally it was used to describe the artificial or cultural features 

 only ; but as the science of surveying was developed, and the relief 

 became an important feature of topographic work, by almost uni- 

 versal practice, it was defined to include both artificial and natural 

 features. To restrict its meaning now to the relief features will 

 drive out the only word we have that represents the " face of the 

 earth and all there is upon it," and gives us nothing in its place. 

 Would it not be better to adhere to " relief of the topography," 

 or '' orography," or even coin a new word, than part with " topog- 

 raphy " in its comprehensive sense ? 



It may be, as Mr. Baker states, that the object and purpose of 

 topographical surveys is the production of topographical maps ; 

 but it is far from conclusive when he defines a topographical map 

 as one " with an accuracy and detail sufficient for all general pur- 

 poses," and that such a map " is not made for any one specific pur- 

 pose, any more than a jack-knife is." " General purposes " is a 

 very catching expression, but very hard to define in a topographic 

 sense ; it is probably a near kin to "ordinary" in the classification, 

 but surely neither of them should be acceptable in defining or 

 classifying an exact science. If the comprehensive meaning of 

 " topography" is the true one, the topographic survey will serve all 

 purposes in which topography may have a value, whether they are 

 of the alleged " general " nature, or specific. But such surveys are 

 necessarily expensive, and they are only undertaken by those na- 

 tions that have use for such detailed results. Mr. Baker produces 

 a table showing the scale of publication adopted for the general 

 maps of European countries, leaving the inference that the surveys 

 are made with this scale of publication in view. Such is the case 

 in some instances ; but the exceptions go to prove the rule, that, 

 where a knowledge of all the topography is valuable, the working 

 scales are three to six times larger than the general publication 

 scales. This is substantial evidence that the detailed knowledge 

 of the topography has a far greater economic value than the gen- 

 eral knowledge. If it were not so, the great expense of the large- 

 scale surveys would not be incurred. 



In the following table I have added to Mr. Baker's figures the 

 scales on which the surveys are first mapped. 



India 



Russia 



Germany 



Norway 



Portugal 



Austria Hungary, 



England 



Sweden 



Italy 



Denmark 



Switzerland 



Publication Scales. 



: 75000 

 : 63360 

 : 50000 



: 50000 



Scale of Surveys, 



63360 

 15840 

 3960 



5000 to 1 : 25000 



50000 and larger 



loooo " 1 : 40000 



25000 " I : 28800 



2500 " 1 : 10560 



: 25000 and t : 50000 



It is more instructive as now compiled, and shows among other 

 things that the scale of a map depends upon the character of the 

 subject, as well as the purpose for which it is constructed ; and we 

 thus see how a complete topographic survey will furnish maps for 



