150 LETTERS ON ENTOMOLOGY. 
is composed of at least four thousand others ! 
The house spider fixes her thread to one side of 
a corner, and walking along the wall to the 
other, draws it across and fixes the other end. 
This thread she renders strong by repeating the 
operation two or three times, and then draws 
threads from it in various directions, the inter- 
stices of which she fills up by running from one 
to the other, and thus connecting them. You 
may often see the garden spiders at work in the 
mornings of autumn, and it is highly amusing 
to watch them. They often have to extend their 
main line across places apparently unconnected, 
between branches of trees, between buildings, 
and even plants growing in the water. The 
way in which they perform this is shown by 
putting a spider on the top of a stick, having 
the lower end in a vessel of water. After try- 
ing all other modes of escape, it will dart out 
numerous fine threads, so light as to float in 
the air, some one of which attaching itself to a 
neighbouring object, furnishes a bridge for its 
escape. This is probably the means by which the 
geometric spiders form their astonishing webs. 
The threads of the house spider's web are all of 
the same kind of silk, but the garden spider's is 
composed of two sorts ; the radii are not ad- 
