38 SPIDERS [CH. 



Very likely it was not obvious to the reader why 

 he Avas recommended to select a particularly calm, 

 sunny autumn day for his study of spider aeronautics ; 

 a strong steady breeze might well appear more 

 suitable for the purpose. Yet he would find these 

 operations at a standstill on a windy day, and the 

 best possible conditions are a still warm morning 

 after a spell of cooler weather. The lightest air- 

 currents serve to float the delicate silken threads, and, 

 what is more important, the increase of temperature 

 causes an upward draught which rapidly carries the 

 spider to a useful height where it sails gently away 

 instead of being swept roughly over the surface of 

 the ground. 



CHAPTER VI 



AGELENA 



BEFORE going farther afield, let us investigate 

 one of the spinners of the sheet-webs that are so 

 unpleasantly familiar in the house. We object to 

 them on very obvious grounds, first as evidence 

 of neglect and bad housewifery, and secondly as 

 repulsive objects when covered by accumulations 

 of dust which their firm texture and their durability 

 make inevitable. 



