VOL. IV.] PHILOSOPHICAL thansactions. 3/9 



These snails are to be found frequently under the loose bark of trees, as old 

 willows, and in the ragged clefts of elms and oaks, &c. but no where else, that 

 I could observe. 



All spiders that spin a thread, (those which we call shepherds or long-legged 

 spiders never do,) produce these threads observable in the air in summer in 

 such infinite quantities every where, especially towards September. I had ex- 

 actly marked all the ways of weaving used by any sorts of them, dYid in those 

 admirable works I had always observed that they still let down the thread they 

 made use of, and drew it after them. At length, inclose attending on one that 

 wrought a net, I saw her suddenly in the mid-work to desist, and turning her 

 tail into the wind, to dart out a thread with the same violence that water spouts 

 out of a spring ; this thread, taken up by the wind, was in a moment emitted 

 some fathoms long, still issuing out of the belly of the animal; by and by the 

 spider leaped into the air, and the thread mounted her up swiftly. 



After this first discovery, I made the like observation in almost all the sorts 

 of spiders I had before distinguished; and I found the air filled with young and 

 old, sailing on their threads, and undoubtedly seizing gnats and other insects 

 in their passage ; there being often as manifest signs of slaughter, as legs, wings 

 of flies, &c. on these threads as in their webs below. Many of these threads 

 that came douTi out of the air were not single, but snarled and with complica- 

 ble woolly locks, now more now less ; on these I did not always find spiders, 

 though many times I had found two or three upon one of them ; whereas when 

 they first flew up, the thread was always single, or but little tangled, or thicker 

 in one place than another. I observed them get to the top of a stalk or bough, 

 or some such thing, where they exercise this darting of threads into the air, and 

 if they had not a mind to sail, they either swiftly drew it up again, winding it 

 up with their fore feet over their head into a lock, or break it off short, and let 

 the air carry it away. This they will do many times together, and you may see 

 those that have chains of these locks or snarled thread before them, and not 

 yet taken flight. 



Again, I found, that after the first flight, all the time of their sailing they 

 make locks, still darting forth fresh supplies of thread to sport and sail by. It 

 is further to be noted, that these complicated threads are much more tender 

 than our house webs. 



In winter, about Christmas, I have observed them busied in darting ; but few 

 of them sail then, and therefore but single threads only are to be seen ; and be- 

 sides, the young ones only of last autumn's hatch are then employed, and it is 

 more than probable that the great ropes of autumn are made only by the large 

 ones, and upon long passages and summer weather, when great numbers of prey 

 may invite them to stay longer up in the air. 



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