how Spiders effect their aérial Excursions. | 451 
complicated structure, resembling ravelled silk of the finest qua- 
lity and clearest white. They were of various shapes and di- 
mensions, some of the largest measuring upward of a yard in 
length, and several inches in breadth in the widest part; while 
others were almost as broad as long, presenting an area of a few 
square inches only. 
These webs, it was quickly perceived, were not formed in the 
air, as is generally believed, but at the earth’s surface. ‘The 
lines of which they were composed being brought into contact 
by the mechanical action of gentle airs, adhered together, till by 
continual additions they were accumulated into flakes or masses 
of considerable magnitude, on which the ascending current, 
occasioned by the rarefaction of the air contiguous to the heated 
ground, acted with so much force as to separate them from the 
objects to which they were attached, raising them in the atmo- 
sphere to a perpendicular height of at least several hundred 
feet. I collected a number of these webs about mid-day as they 
rose, and again in the afternoon, when the upward current had 
ceased and they were falling, but scarcely one in twenty con- 
tained a spider; though on minute inspection I found small 
winged insects, chiefly aphides, entangled in most of them. 
From contemplating this unusual display of gossamer, my 
thoughts were naturally directed to the animals which produced 
it; and the countless myriads in which they swarmed almost 
created as much surprise as the singular occupation that en- 
grossed them. Apparently actuated by the same impulse, all 
were intent upon traversing the regions of air; accordingly, 
after gaining the summits of various objects, as blades of grass, 
stubble, rails, gates, &c., by the slow and laborious process of 
climbing, they raised themselves still higher by straightening 
their limbs; and elevating the abdomen, by bringing it from the 
usual 
