INTRODUCTION 



The U. S. Navy Electronics Laboratory thermistor chain was 

 obtained in 1961. x (See list of references at end of report. ) With 

 the new thermistor chain it has become possible to measure verti- 

 cal sections of the temperature structure from the surface down to 

 800 feet. USS MARYSVILLE (EPCE(R) 857), from which the chain 

 is operated, is capable of steaming anywhere in the oceans (fig. 1). 



The first cruise with the thermistor chain was made in June 

 1961 in order to test the equipment over the nearby San Diego 

 Trough. The results of this cruise have already been reported. 



The second cruise, the subject of the present report, was 

 made between 10 and 14 July 1961 off Southern California. The 

 purpose was to investigate the nature of internal waves in the deep 

 ocean regions. The ship's course was three-directional, consist- 

 ing of a run of about 12 hours directly offshore, another of 12 

 hours parallel to shore, and a third of 12 hours directly toward 

 shore (fig. 2). In addition to this course, four circles of 2-mile 

 diameter and two of 6-mile diameter were traversed in an at- 

 tempt to determine the direction of internal-wave propagation 

 from the doppler effect created through changing the direction of 

 tow. 



EQUIPMENT 



The oceanographic chain hoist, ' the thermistor chain, and 

 the drum on which the chain is wound are large and rugged, weigh- 

 ing 37, 500 pounds. The chain is composed of flat links about 1 

 foot long, 10 inches wide, and 1 inch thick. At the end of the 

 chain is a 2300-pound streamlined weight, called a "fish, " to hold 

 it down. 



About 100 pairs of insulated electrical leads fit through 

 grooves inside the flat links. Every 27 feet the electrical wires 

 connect with the temperature sensors, or thermistor beads. 



