S92 ON THE ASCENT OF THE SPIDER 
I first began my experiments and observations on this 
curious subject on the 2d of June 1822. One of these spi- 
ders alighted on me, and glanced off from my hand with 
considerable rapidity : thermometer IT in the shade. 
It is impossible to walk in the fields without being sa- 
luted by several of these insects ; they will be chiefly no- 
ticed by alighting on the hat, and descending by a thread 
before the face : in this way they are easily caught, as they 
will drop into a chip-box, and may be secured. Received 
on a pencil, or the like, they will soon be perceived to 
oscillate like the pendulum; oftentimes rising from the 
perpendicular into the horizontal plane, at each ascent pro- 
jecting a thread into the atmosphere; and, finally, by a 
twitch or jerk, the insect breaks from its anchorage, and 
ascends. It is difficult to determine whether the insect 
bites off' the connecting thread, or breaks it off by main 
physical strength ; but from the sudden twitch which ap- 
pears to detach it, I am inclined to believe that the latter 
is the fact. 
Sometimes the aeronautic spiders will take their flight 
immediately from the surface on which they alight, if the 
day be warm and sultry; but generally they descend to 
from 6 to 18 inches^ perhaps the better to insulate them, 
and that, suspended by a pliant thread in free space, they 
may more freely propel their threads into the atmosphere. 
Not unfrequently the propulsion of a solitary thread will 
bear them aloft, but the air must then be very warm, and 
its electric character be high. Sometimes the ascent is rapid, 
and cannot be followed by the eye ; at other times it is slow 
and majestic. Occasionally the ascent is quite vertical, and 
at other times the animal sails on the bosom of the air, ei- 
ther in the horizontal plane, or at angles more or less acute. 
It will be also found that there are particular seasons of 
the year best calculated for this singular exhibition : spring 
