232 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



Resists 

 Wind. 



of Foun- 

 dation 

 Lines. 



and Epeira triaranea in the full sweep of a strong gale, blowing over a 

 near by bay of the sea, and are scarcely damaged. Sometimes, it is true, 

 the webs are blown away or lashed into threads wholly or in 

 part ; but frequently they will stand all the ordinary high winds 

 and even some of the extraordinary ones wliich blow oif the 

 ocean. This is true even when they are spun quite near the beach, and 

 have little protection under the lee of surrounding objects. 



An illustration of the remarkable strength and elasticity of the founda- 

 tion lines of orbwebs appears in a biographical notice of the distinguished 



astronomer, the late Gen. 

 Ormsby M. Mitchell, printed 

 with an edition of 

 Strength his lectures, i Prof. 

 Mitchell directed 

 his great ingenuity 

 to the problem of 

 causing a clock to record its 

 beats telegraphically, and at 

 the same time perfectly per- 

 form the work of a time- 

 keeper. The required makes 

 and breaks in the battery 

 were effected by means of a 

 cross of delicate wire and a 

 mercury cup. ]\hiny obstacles 

 having been overcome, there 

 arose the great difficulty of 

 procuring a fibre 

 sufficiently minute 

 and elastic to con- 

 stitute the physical 

 union between the top stem 

 of the cross and the clock 

 l)endulum. Various materials 

 were tried, among others a 

 delicate human hair, the very 

 finest that could be obtained, but this was too coarse and stiff. Its waul 

 of pliancy and elasticity gave to the minute "wire cross" an irregular 

 motion, and caused it to rebound from the globule of mercury into 

 which it should have plunged. " After many fruitless attempts," says 

 Prof. Mitchell, "an appeal was made to an artisan of wonderful dexter- 

 ity ; the assistance of the si)ider was invoked ; his web, perfectly elastic 



Prof. 



Ormsby 



Mitchell. 



Fig. 218. Section of a dew laden orbweb. (.Magailied.) 



^ The A.stronoiny of Uu' IJible', piige 35. 



