(36 THE ELEMENTS 



and are found among the rocks near 

 the shore, in the Mediterranean and 

 Indian Ocean. 



The Argonauta argo is the Nauti- 

 lus so famous amongst the ancients, 

 and often mentioned in the writings 

 of Pliny and others. It is supposed 

 that in the earliest ages of society, 

 this shell suggested to men the first 

 idea of usinff sails. In calm weather 

 it rises to the surface of the water, 

 (which it does by discharging a quan- 

 tity of fluid, that rendered it specifi- 

 cally heavier than the sea-water,) and 

 spreads its arms over the shell, which 

 answer the purpose of oars ; it then 

 throws out and expands a double 

 membrane, which it can oblique in any 

 direction at pleasure, this answers the 

 purpose of a sail, and by this it is im- 

 pelled forward by the breeze, like a 

 ship under sail; two of its arms hang 

 over the shell, and serve as rudders 

 or oars, to direct its course. In the 



