Naval Photo Interpretation 
TRANSVERSE AND DIVERGING WAVE SYSTEMS 
Every ship on her way through the water is accompa- 
* * nied by a pressure system generating groups of waves, con- 
sisting partly of transverse waves having their crest lines 
at right angles to the direction of motion, and partly of 
slightly curved waves, called the diverging system, see 
Fig. l. The wave pattern shown in the diagram was first 
   
  
    
  
  
  
  
  
   
  
   
  
  
/9°28° 
* * PRESSURE 
POINT uni 
" « 
ê + " 
DIVERGING Te 
Fig. 1. 
e . arrived at mathematically by Lord Kelvin, who presented 
the theory of the disturbance caused by a travelling 
"pressure point', the bow of a ship moving in deep water 
in a straight line at constant speed. The outer limits of 
the waves form an angle of 19? 28^ with the course of the 
ship, regardless of her size, shape, or speed. 
William Froude, the inventor, who determined the 
resistances of ships from measurements of the resistances