64 MR JOHN AITKEN ON DEW. 



of turnips, for instance. The Swedish variety exudes freely, the liquid forming 

 little drops fringing the leaves, while the moisture exuded by the other varieties 

 spreads itself over the leaves. One result of this is, that after dewy nights the 

 softer varieties dry sooner than the Swedish, because the exuded moisture, by 

 spreading itself over the surface of the leaves, dries up much more quickly 

 than the drops on the others. This seems to be the explanation of a fact fre- 

 quently observed by sportsmen and others who have occasion to walk through 

 turnip fields on autumn mornings, namely, that the softer varieties generally 

 wet them much less than the swedes. Again, after rain the swedes take longer 

 to dry than the others, because their surfaces do not get wet, but the water col- 

 lects in drops, imperfectly attached to them, and also fills the hollows of their 

 leaves ; whereas the other kinds get wet, and the water runs off them, leaving 

 only a thin film on their surface, which dries up much more quickly than the 

 drops on the others. Further, when we walk through turnips immediately after 

 rain, our feet brush the drops from the swedes in showers, which rapidly wet 

 us, while the water adheres to and does not so easily leave the surfaces of the 

 others. 



This last part of the investigation takes us a step further, and shows us that 

 not only is the dew-drop a result of the vitality of those plants on which it 

 forms, but that much of the wetness spread over the leaves of others on dewy 

 nights is produced by moisture exuded by the plants. 



