ENGINEERING SKILL OF SPIDERS. 213 



to the geometrical part of the web was scarcely perceptible. 1 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 2 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 



A Scotch p j ge( j j n jnidai^ 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. 3 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- a ] 3OU t half an inch long, three-eighths wide, and one-eighth 

 ican . 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 

 T) ht 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. 4 

 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." 5 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, 

 ij 1 " M viz., that when Epeira makes a web in the path of a garden or 

 Case 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. 



2 J. F. D., id., page 283. 



3 J. E. 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. Civ. Di Genova, Ser. 1, IV., 1873, page 39. 



