CHAPTER Xlll. 

 ENGINEERlXf! SKTT.L OF SPIDERS. 



I. 



Tt is a generally received opinion, even among well informed natural- 

 ists, and is certainly a fixed pojjular tradition, that Orbwea\ing spiders 

 construct a web that is jierfectly true in its geometric arrange- 

 Imperfect ment. Tliis lias highly redounded to the praise of tiie little 

 Geomet- weaver, particularly as she may spin by the sense of touch with- 

 out the aid of sight. ^ It seems a pitv to destroy any notion 

 ment *'''^^ ^^^'"^^ throw around despised Arachne a greater measure of 



respect in the popular mind, in which her standing is, as a rule, 

 anything but favorable. However, in the interests of truth it must be said 

 that concerning this point the popular opinion is only true in a general 

 sense. There is nuich irregularity in the execution of many geometric 

 webs. 



The radii are not laid out witii absolute mathematical accuracy, but 

 arc separated from each other by distances varying considerably. If, for 

 example, one carries the eye around the circumference of this large orb, 

 he will find liere two radii terminatiiig upon their marginal foundation 

 lines at jioints lialf an incli apart, and there two others tiu-ce-fuui'ths of 

 an incli apart, and in yet another place two others separated by one and 

 a half inciies. It is true that all orbs are not laid out as irregularly as 

 tliis from whose measurements I have quoted, l)ut more or less irregularity 

 will be found on almost every web, particularly upon those spun Ijy adult 

 sjiiders. Again, the radii will be found blending with one another at 

 various points instead of converging regularly upon a central point ; and 

 more or less departures of a like kind from mathematical accuracy char- 

 acterize the spiral concentrics. Howcn'cr that may be, the actual facts in 

 the case are sufficiently striking, and (lie general regularity of plan ami 

 the frequent close approach to geometric accuracy in special oil is 

 Symme- ^.g remarkable enough without resorting to exaggerations. in 

 p .. , fact, it may well be doubted that absolute regularity, in tiie 

 sense of symmetry, would be the most desirable for the uses of 

 a web. The departures from mathematical accuracy may mark, and I 

 have reason to believe do mark, a higher measure of utility, and 



' See Wood's " Homes without Hands," page 321. 



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