622 THE POPULAR SCIENCE MONTHLY. 



are frequently and deeply flooded over, and yet the cholera never 

 comes ! 



Just as the disposition to cholera in time and place may be due to 

 two causes, so may the immunity from cholera be dependent either on 

 the physical nature of the soil, as is the case in parts of Traunstein and 

 Kienberg, or on the condition of the soil as regards moisture, as hap- 

 pened in the low-lying parts of Munich during the summer epidemic 

 of 1873, or at Augsburg during the summer and winter of 1873, or at 

 Munich in 1866. Such a degree of wetness as prevailed on those oc- 

 casions may be a constant condition in some places ; to this latter group 

 the low-lying districts of Lyons belong. Indeed, both factors are at 

 work in Lyons. In the high-lying parts the granite comes to the sur- 

 face in many parts, and so a very efficient and natural drainage is 

 secured. These districts may always be said to be free from cholera. 

 The soil of the low-lying parts, situated on the banks of the Rhone 

 Brotteaux, Guillotiere, and Perroche, has always a certain degree of 

 humidity, which cholera when imported has to encounter. This moist- 

 ure of the soil of parts of Lyons is dependent not only on rain, but also 

 on the river Rhone. The impermeable bottom of its bed is of solid 

 granite, to which fact I could bear personal testimony. This stratum 

 of granite stretches from the left bank of the Rhone far inward, so 

 that Lyons is built upon it ; all the springs lie below the level of the 

 surface of the waters of the Rhone, and so rise and fall with the 

 river. In Paris, in Munich, and in Berlin the conditions are otherwise. 

 Here the level of the subsoil water is above the level of the waters 

 of the Seine, Isar, and Sj^ree, respectively ; this relation is the most 

 general, so that Lyons is exceptional. In Lyons it may be said that a 

 part of the Rhone runs subterraneously, so that the soil receives water 

 from the river ; whereas in Paris, Munich, and Berlin the direction of 

 the water is constantly from the soil to the river. When the water 

 rises in the beds of the Seine, Isar, and Spree, there is no penetration 

 of the water into the porous soil, but rather a damming and stagnation 

 in the discharge of the subsoil water. The granite of the Rhone, 

 chiefly composed of large blocks of quartz, contains also much fine 

 sand, which is able to suck up water to a considerable height in its 

 capillary spaces, possibly as high as the zone of evaporation. I inves- 

 tigated the hardness and moisture of this quartz by actual digging. 

 This part of Lyons is only at times free from cholera, and would be 

 susceptible of an epidemic were some of its water taken away. That 

 Lyons may be fatally visited was shown in the year of cholera, 1854. 

 As I was studying the conditions of cholera in Lyons, I found that in 

 1854 no less than 500 deaths occurred from the disease ; while at other 

 times the town escaped with a dozen deaths. It also transpired that 

 nearly three fourths of the deaths happened in Guillotiere, and I must 

 say, therefore, that in the year 1854 at least a part of Lyons suffered 

 from an epidemic of cholera. The Lyonese were not pleased with this 



