56 THE OCEAN FLOOR 



the equipment, which was then installed on the 

 "Albatross," Weibull himself supervising the work 

 during the first transatlantic crossing.- Since then the 

 method has been much improved by introducing the 

 wire recorder for the immediate registering of the 

 echoes, a transfer to oscillograms being made later in 



Wa/*r surface. 



Fig. 22. Weibull's scheme for re- 

 flection measurements 



the laboratory on shore. A highly simplified explanation 

 of how the method works is given in Figure 22, while 

 23 is a reproduction of one of WeibulFs most interest- 

 ing oscillograms, obtained in the central Atlantic Ocean 

 between Madeira and the Mid-Atlantic Ridge. We can 

 see three breaks in the record, due to deep echoes thrown 

 back by three different reflecting layers in the bottom, 

 the uppermost at a sediment depth of 5,150 feet and the 



