ENGINEERING SKILL OF SPIDERS. 213 
to the geometrical part of the web was scarcely perceptible.t The fact is 
not questioned, but the inference here made that the spider purposely drew 
up the stone as a counterpoise is wholly gratuitous. 
Another correspondent? contributes a similar case observed by a lady 
in Scotland. She was walking through a wood when she suddenly noticed 
at some distance from the ground a small stone apparently 
poised in midair, but which, on closer examination, was seen 
to be suspended by a long thread from a spider’s web, built 
between two trees. 
Yet another fact is recorded in the same journal, although it is quoted 
from an American magazine. A gentleman, while passing along one of 
his garden walks in Brooklyn, saw, upon a cherry tree, a spider’s web 
which was spun within foundation lines that stretched from the trunk to 
fastenings that ran out upon a large limb. The web rose at an angle of 
perhaps thirty degrees from the earth. The spider had by some means 
formed a corner downwards and suspended from it a little stone 
An Amer- about half an inch long, three-eighths wide, and one-eighth 
ican Ex- 
eragley thick. This was well secured, and hung some eight or ten 
inches below. This weight kept the web taut, and swung 
slightly as the wind affected it, and there it remained for several days. 
Still another correspondent declares that, like many other persons, he 
has observed a small stone suspended from a spider’s web, but expresses 
his doubt as to the suspension being an intentional act of the 
spider, and gives what I regard to be the true explanation, name- 
ly, that by the shrinking of the threads, or some change in the 
position of the web supports, the stone had been raised from the ground. 
In all the above cases it will be observed that the evidence for intentional 
engineering is simply the fact of the stone’s position, which is equally ex- 
plained as above. 
Professor Pavesi has recorded a similar experience in his “Spiders of 
the Canton Ticino.”® His attention was first called to the fact by a friend, 
and he was at the outset incredulous, but had confirmed his original obser- 
vation. He begins with a statement which I can corroborate, 
A Scotch 
Case. 
A 
Doubter. 
ae .,. Viz, that when Epeira makes a web in the path of a garden or 
hae other sites between trees, it is her custom to drop a thread from 
the lower angles of the polygonal foundation lines of her net, 
which lines converge upon this single cord. Further, he declares (which is 
contrary to my experience) that upon this cord the spider ties a counter- 
1 John Hepworth, ‘Science Gossip,” November, 1868, page 262. 
2J. F. D., id., page 283. 
8 J. R. S. Clifford, “Science Gossip,” April, 1869, page 94. Quoted from the “New York 
Gardener’s Magazine,” 1841. 
4 George Guyon, id., page 118. 
5 Ragni del Canton Ticino: Annali Mus. Ciy. Di Genova, Ser. 1, IV., 1873, page 39. 
