296 IXSECT AECHITECTURE. 



pound tlie main cord. The preceding figure exhibits this 

 ingenious contrivance. 



Those who may be curious to examine this contrivance, 

 will see it best when the line is attached to any black 

 object, for the threads, being whitish, are, in other cases, 

 not so easily perceived. 



Shooting of the Lines, 



It has long been considered a curious though a diilicult 

 investigation, to determine in what manner spiders, seeing 

 that they are destitute of wings, transport themselves from 

 tree to tree, across brooks, and frequently through the air 

 itself, without any apparent starting point. On looking 

 into the authors who have treated upon this subject, it is 

 surprising how little there is to be met with that is new, 

 even in the most recent. Their conclusions, or rather their 

 conjectural opinions, are, however, worthy of notice; for 

 by unlearning error, we the more firmly establish truth. 



1. One of the earliest notions upon this subject is that of 

 Blancanus, the commentator on Aristotle, which is partly 

 adopted by Eedi, by Henricus Eegius of Utrecht, by Swam- 

 merdain,* by Lehmann, and by Kirby and Spence.f " The 

 spider's thread," says Swammerdam, "is generally made 

 up of two or more parts, and after descending bj^ such a 

 thread, it ascends by one only, and is thus enabled to waft 

 itself from one height or tree to another, even across run- 

 ning waters; the thread it leaves loose behind it being 

 driven about by the wind, and so fixed to some other body." 

 "I placed," says Kirby, "the large garden spider (^Epeira 

 diadema) upon a stick about a foot long, set upright in a 



vessel containing water It let itself drop, not 



by a single thread, but by tico, each distant from the other 

 about the twelfth of an inch, guided, as usual, by one of its 

 hind feet, and one apparently smaller than the other. 

 AVhen it had suffered itself to descend nearly to the surface 

 of the water, it stopped short, and by some means, which 

 I could not distinctly see, broke off, close to the spinners, 



* Swammerdam, part i. p. 24. f Intr. vol. i. p. 415. 



