i 3 4 PHYSICAL SCIENCE BK. in 



a twig or bough and a few days after you can 



4 take out a stone. The mud surrounds the object 

 and gradually coats it over. This will seem the 

 less surprising if you have remarked that the Albula, 

 and, generally speaking, all water charged with 

 sulphur, deposit a coating of it on the banks of their 

 channels and streams. Some one or other of the 

 foregoing causes accounts for the peculiarities of 

 those lakes, whereof who tastes with the lips, in the 

 words of the same poet, 



Goes raving mad or endures a sleep of wondrous depth. 



5 The effect is like that of strong drink, only more 

 violent. Drunkenness is madness until its effects pass 

 off; with a weight like lead it bears down its victim 

 into sleep. In the like manner the strong infusion 

 of sulphur in this water contains a sort of poison 

 that is more potent owing to the noxious atmosphere, 

 and either goads the mind to madness or weighs 

 it down in deep sleep. The river in Lyncestis 

 likewise possesses this baleful power : 



For whoso with intemperate lips has drained a draught, 

 Staggers as if having drunk deep of wine undiluted. 



XXI 



THERE are certain caves a glance down into which 

 has cost people their life. So swift is their destruc 

 tive power that it kills in flight the birds that cross 

 them. That is the kind of air and the kind of 

 place from which waters of death escape. If the 

 infection of the air and place is less severe, the 

 damage is less fatal too, merely affecting the sinews 

 like men overpowered by intoxication. I am not 



