CHAPTER XI 



NATIONAL SURVEYS AND MODERN 

 ATLASES 



Cartography since the early decades of the nineteenth 

 century is characterized by the execution of regular topo- 

 graphical surveys as national undertakings. Most has been 

 accomplished in Europe, in some countries of Asia (e.g. India, 

 Japan, the Dutch East Indies); in the United States and 

 Canada; and in Egypt and parts of North Africa. Though 

 similar surveys have been begun elsewhere, progress has not 

 been rapid, and great areas of the earth's surface are still 

 unmapped at medium scales on a systematic trigonometrical 

 framework. For these the cartographer depends upon miscel- 

 laneous and unco-ordinated material of varying quality, 

 produced by travellers, boundary commissions, railway and 

 road development, settlement schemes, and mining and 

 similar concessions. To these must now be added rapid recon- 

 naissance surveys, mainly from the air, of considerable areas 

 carried out during the last war. 



The second major advance has been in the enlarged scope 

 of atlases, and the increasing use of mapping as a technique in 

 dealing with a wide variety of problems in physical and human 

 geography, and in administration. This progress was con- 

 siderably assisted by the change from engraving on copper 

 plates to colour lithography and its modern developments, 

 which allow a great variety of detail to be clearly shown. 



The great national surveys of the nineteenth century rested 

 upon methods resembling in general those of the Cassinis. 

 These were gradually refined as instrumental design pro- 

 gressed, and corrections were applied to the observations to 

 allow for factors previously neglected. These included correc- 

 tions for refraction and the curvature of the earth's surface, 

 for changes in temperature and other conditions affecting the 



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