It was decided to try a spai^ Mark III pressure head (with bhe 

 Heceta Head shore recorder) as a surge recorder. The normal felt 

 damping on the air chamber of the !,!ark III was replaced with a single 

 thickness of felt and some washers which cut the effective opening 

 to about 3/16 inches. As the pressure head was to be placed in less 

 than four feet of water (below !ff,nO this Tras necessary so that the 

 instniinant vrouid centar and yet not folloT/ the tides. It must be 

 rsmambsred tliat only the sur^ carv.^ through the bay opening and that 

 the short period waves were mechanically damped out by the nature of 

 the entrance. The head was placed st the mouth of the bay (as shown 

 on the sketch map) at the point of maximum surge amplitude and con- 

 veniently' located with respect to the recorder shack and power supply. 

 It operated from about I6OO to 2200 on October 29 and from 0930 to 

 1200 on October 30. The installation w^s hastily put together and 

 co"ld adTTiittpdly b? improved uponj however, it did give a record of 

 lue sui'ge which had only been recorded visually before. The records 

 and observations seem to indicate that (1) certain locations such as 

 Depoe Bay may make ideal places for the installations of long pariod 

 wave recorders because of their natural ability to dan^) out short 

 period waves; (2) there is enough vertical movement in some surging 

 to allow a vertical (pressure) type instrument to make a record; 

 (3) surging and long period waves may be related to large local 

 storms as well as to mora distant storms; and (^) records of long 

 period waves are much like those of short period waves — they seem to 

 have maximum arrivals of 3-5 waves at correspondingly longer time 

 intervals , 



The results are inconclusive for the following reasons: (1) 

 Since only one recorder unit was available there was no simultaneous 

 record of ocean swell, (2) The maximum surging had died down before 

 the recorder vras operating. (3) A somawhat different type of 

 instrument might have given a better response (by measuring the more 

 intense horizontal component). 



3^ 



