ARGONAUT AND GEOMETELi. 207 



nature, working similar ends by analogous principles of 

 action implanted within creatures most widely sepa- 

 rated in organization and endownnents. Surely there 

 could be nothing humiliating in that ?" 



" We were presently joined by a party of gentlemen, 

 among whom was one of Mr. Roebling''s assistants upon 

 the Brooklyn Bridge. He was greatly interested in our 

 conversation, and I ventured to carry my analogy a 

 little further. This gentleman, on a previous occasion, 

 had given me a detailed account of the building of the 

 caissons upon which the immense stone piers had been 

 constructed. I asked him : 



"Am I right, Mr. Assistant, in supposing that the 

 principles upon which these caissons have been built are 

 those of the diving-bell and compression of air ?" 



" Yes ; I suppose that we might say that very truly." 

 " Well, then, I will venture to say that I can find the 

 same principles embodied in, I will not say anticipated 

 l)y the work of a spider. 



"Well, sir," said the Assistant, "you may, doubt- 

 less, succeed ; but haven't you undertaken a pretty 

 heavy contract ?" 



" You shall judge the issue. Here now," taking a 

 note-book from my pocket, "is a rough sketch of the 

 cell or nest of the water spider {An/i/roneki aqwitka)^ 

 which is found in some of the streams of England. It 

 is an egg-shaped silken sac, about the size of an 

 acorn, which is ^voven upon water-plants underneath 

 the surface. In the bottom part of the cell is a small 

 circular opening. The; cell, as fii-.-^t WM)ven, is simply a 



