LIMJTATIOXS OF KNOWLEDGE OE DEEP SEA 79 



the information would be very incomplete. Such a cror<'-e 

 as the Grand Canon of Colorado would have but a bare 

 chance to be noted ; a volcanic peak like /Etna, though it 

 rises two miles above its base, would most likely escape 

 observation. 



If our imagined super-terrestrial beings should limit tlieir 

 inquiries to the facts developed by the plummet, they would 

 have but the most general notions as to the form of the sur- 

 face they were exploring. We can conceive them using the 



Diagram showing the Position of a Deep-sea Dredge as the Line is Paid Out from the Stern of ihe Ship 



The letters G, G', etc., show the position and effect of the weight which is used to bring the dredge into 



the proper attitude. 



Other aids in their research which have been devised b\- the 

 explorers of the deep sea : the dredge, a contrivance like a 

 scoop, which is dragged over the bottom, so as to collect a 

 sample of the deposits which arc forming there. A few thou- 

 sand essays with this instrument would certainly give some 

 notion as to the nature and variety of the organic forms which 

 people the surface of this sphere, and are contributing their 

 bodies to its dust on sea-floor and land. Yet we readily fancy 

 that these observations would afford but an inadequate basis 



