60 STUDIES, SCIENTIFIC AND SOCIAL CHAP. 



which would be a quarter of a mile in circumference ; but 

 the visibility of inequalities of surface depends not on their 

 actual magnitude so much as on their steepness or abrupt- 

 ness, and most hills and mountains rise with considerable 

 abruptness from nearly level plains. All irregularities of 

 surface are appreciated by us owing to the effects of light 

 and shade produced by them ; and by a proper arrange- 

 ment of the illumination the smallest deviations from a 

 plane can be easily rendered visible. Again, the slopes of 

 mountains are always much broken up by deep valleys, 

 narrow gorges, or ranges of precipitous cliffs, which give 

 a distinct character to mountainous countries, thus pro- 

 ducing striking contrasts with lowlands and plateaux, which, 

 when brightened by appropriate colouring and brought to 

 view by a suitable disposition of the sources of light, would 

 give them any desired amount of distinctness. 



It is proposed that the globe shall always be kept up to 

 the latest knowledge of the day, by adding fresh details 

 from the results of new explorations in every part of the 

 world ; so that, by means of photography, maps of any 

 country or district could be formed on any scale desired ; 

 and for a small fee the globe might be available to all map- 

 makers for that purpose. Such maps would be more 

 accurate than those drawn by any method of projection, 

 while the facility of their construction would render them 

 very cheap, and would thus be a great boon to the public, 

 especially whenever attention was directed to any particu- 

 lar area. 



M. Reclus states the scientific and educational value of 

 such a globe as due to the following considerations (1) 

 its accuracy of proportion in every part, as compared with 

 all our usual maps, especially such as represent continents 

 or other large areas ; (2) the unity of presentation of all 

 countries, by which the erroneous ideas arising from the 

 better-known countries being always given on the largest 

 scale will be avoided ; and (3), that the true proportions of 

 all the elevations of the surface \yill be made visible, and 

 thus many erroneous ideas as to the origin, nature, and 

 general features of mountain ranges, of valleys, and of 

 plateaux, will be corrected. He has fixed upon the scale 



