Fig. 5. Meteor "glass-tube" tjrpe of bottom sampler 



Fig. 7. The Wenner salinity bridge. An apparatus 

 giving the salt content in a sample of sea water 

 by measuring the resistance it offers to the pas- 

 sage of an electric current , 



Fig. 6. Paul at the plankton pump. 

 This device makes a census of 

 the microscopic life floating at 

 any desired depth 



Fig. 8. The radio receiver designed by the Naval Research Laboratory and 

 used on the Carnegie , bringing us messages from home and keeping us in 

 touch with headquarters through radio amateurs in all countries 



20 



