V. MAPS, ETC. 811 



3226. Terrestrial Globe of 34 cm. diameter. 



Dietrich Reimer, Berlin. 



3227. Terrestrial Globe on an iron stand with semi-meri- 

 dian. Dietrich Reimer, Berlin. 



3228. Terrestrial Globe. Dietrich Reimer, Berlin. 



3231. Terrestrial Globe, 48 cm. diameter. 



Ernst Schotte, Berlin. 



3232. Pour Maps. M. Dclesse, Paris. 



1. Agricultural Map of France. On this map the various cultures or crops 

 are shown by conventional colours, the shades of which are proportionately 

 darker according as the returns or yields are more important. 



If we consider the arable lauds, which occupy the largest portion of France,, 

 they will of course vary yearly in their produce, but it is possible to form 

 a money estimate of their average annual return per hectare. 



By studying the figures for the cantons, taking into account their shape, 

 as well as their elevation, and the mineral composition of the soil, curves 

 have been traced showing the annual revenues of 20, 40, 60, 80, 100, and 120 

 francs. 



For the woods, meadows, and vineyards, where the culture is permanent, 

 there have also been traced curves of equal revenues, showing the average 

 returns per hectare. 



Giving to the cultivated lands, the woods, fields, and vineyards, their con- 

 ventional colours, the depth of shade of these has been graduated according 

 to the various curves to which they correspond. 



Although the map is on a scale of 1:4,000,000, it nevertheless enables an 

 estimate to be formed of how the agricultural riches of France is subdivided. 



2. Hydrological Map of the Seine and Marne. The hydrological map of 

 the departments of the Seine and Marne is on a scale of 1:100,000, ,and shows 

 the underground stores of water of the region of La Brie. These water 

 supplies are represented by certain conventional colours, and their form has 

 been determined by the geological investigation of the subsoil, from surveys 

 and borings made over a network of wells. In fact, the surface represents the 

 levels which have been ascertained for each well below the level of the sea, 

 and these are shown by horizontal curves of 20 metres distance, so that it is 

 very easy to trace the course of the flow of the water supplies. 



In the region of La Brie, the principal subterranean water beds correspond 

 with the most important argillaceous strata, that is to say, the green clays, 

 the plastic clays, and in certain points, the building limestones of La Beauce. 



Moreover the subterranean water-bearing beds known as those of infiltra- 

 tion correspond to the various watercourses which traverse La Brie, and 

 especially the rivers, such as the Seine and Marne. 



The water-bearing beds over the green clays is by far the most important 

 in the plateau of La Brie, whilst in the valleys the wells are supplied by the 

 beds of infiltration. 



The hydrological map of the Seine and Marne enables a judgment to be 

 formed of the depth it would be necessary to attain in order to obtain a 

 water supply, and an opinion can also be formed of the geological nature of 

 the soil which would be met with in boring. A judgment can also thus be 

 formed of how the water sources and beds act in an absorbent soil like 'chalk ; 

 a question which is of considerable interest at the present time, -when a- tunnel 

 is proposed between France and England. 



