frequencies into the temperature record. This contamina- 

 tion can be reduced somewhat by thermal lagging of the 

 thermistors, but it cannot be completely eliminated. A 

 high thermal gradient corresponds to a high stability fre- 

 quency and internal waves can progress at a high frequency. 

 If internal waves are to be passed at full amplitude, then 

 surface-wave frequencies cannot be completely eliminated 

 from the record by thermal lagging. 



An important advantage to jetting transducer supports 

 into the bottom is that relative accuracy approaching labora- 

 tory accuracy can be obtained. Transducer placement for 

 measuring internal waves is analogous to the design of a 

 directional radio antenna or a directional sound transducer; 

 that is, with a certain placement, a certain response can be 

 obtained. An array of transducers can be installed, depend- 

 ing on the requirements, as an antenna with a given response. 

 Transducer spacing can be controlled by the diver, and the 

 scientist can be assured of the accuracy he desires. 



In May 196 3 the Marine Environment Division of NEL 

 requested the installation of a circular array of thermistor 

 beads on the shallow ocean floor adjacent to the existing 

 NEL oceanographic tower. The array was to be used in a 

 study of internal-wave vectors and was to consist of forty- 

 eight vertical stanchions, 29 feet apart, forming a circle 

 with a 1395-foot circumference (fig. 1). Each stanchion 

 was to rise 31 feet off the bottom and be capable of support- 

 ing the necessary thermistors and cables. The tripod 

 method of installation was deemed unfeasible for a job of 

 this magnitude and rejected in favor of the jetting method. 



This report describes the devices used to carry out 

 this installation and the method of placement as well as the 

 diving procedures involved, with further applications of 

 these techniques. 



