38 



Observations and Measurements of Ocean Waves 



movement of the staff (see Fig. 23). The construction of the instrument built 

 by Paris is fundamentally similar, except that it is somewhat more stable. 

 A ring-shaped float around the lath is pushed up and down by each wave. 

 These motions are recorded by an automatic recording device affixed to the 

 top of the staff. Pabst (1933) (Hamburg ship-building laboratory) developed 



VJcw§ 



crest 



Fig. 23. Wave height meter by Froude. 



a buoy which proved to be satisfactory for measuring waves, but it seems 

 to be very difficult to make it work when the sea is rough. No measurements 

 with this device have been published. 



Recently wave-recording instruments have been developed or built which 

 either record approaching waves at a point not too far distant from the coast 

 or from aboard a ship. Such instruments have been described by Deacon 

 (1946, p. 13) for the Admirality Research Laboratory, Teddington, and 

 almost simultaneously by Klebba (1945) for the Woods Hole Oceanographic 

 Institution. Although the various instruments which were developed differ 



