36G 
MR WATT ON THE HOIllZONTAL 
thread with great rapidity to the length of several feet or 
yards, and in such a manner as to strike against a particu- 
lar part of any body that may be within the reach of the 
thread. I have very often observed the geometric spiders 
in the act of performing this curious operation ; and I can 
affirm, that the larger individuals seem to be able to hit 
any spot they intend to attach the end of their thread to, 
with almost the same precision that the jaculator fish strikes 
a fly with the drop of water it ejects from its mouth. In- 
deed, the regular disposition of the threads that radiate 
from the centre of the web of these spiders, is a proof that 
they must be capable of directing their lines to a given 
point, as these threads are often five and six feet long. 
The method I at first adopted to discover this very in- 
teresting faculty of the spider, was to place a pretty large 
stone in the centre of a broad plate, and fill the plate with 
water, leaving the upper part of the stone dry : then by 
means of a little clay or putty I placed a slip of wood or a 
straw, a foot or two high, perpendicularly on the stone ; 
some spiders were then placed on the dry part of the stone. 
By this method I perceived the spiders, which have an 
aversion to the water (as they cannot move upon it), make 
their escape from the confinement, by the upper end of the 
piece of wood, or the straw. 
After examining the circumstances of their situation, 
they uniformly had recourse to one of two methods by 
which they made their escape. They either let themselves 
drop down by their lines about two inches from the top of 
the stick, and, turning their spinners towards the wall of 
the apartment, they threw out their threads with great ra- 
pidity till they touched the wall, where they stuck, and the 
instant they struck the wall, they turned round and fastened 
the other ends of the threads to the stick, and thus ran 
across ; — or they ejected a line upwards^ which its buoyancy, 
