Fig. 5- Preformed harness: (a) preformed bead and (b) lead for bead. 



The lower quarter of the chart (Fig. 6) is 

 marked every 6 minutes with a vertical row of 

 16 dots by means of timing pips . For tempera- 

 ture readings the dots represent temperatures 

 at 2-degree intervals from 0° to 30°C. A con- 

 tinuous line marks the temperature of the 

 selected sensor. When the temperature of the 

 bead is known the upper isotherm on the record 

 and all other isotherms are easily identified. 



The depth of the pressure transducer near the 

 end of the thermistor chain varies with ship 

 speed and with subsurface currents . For recording 

 this depth on the lower part of the chart the 

 16 vertical dots represent depth at 60-foot inter- 

 vals from the surface. There is no possibility 

 of confusing the depth record with the tempera- 

 ture record for the values are simulataneously 

 shown on 2 of the dial indicators at the base of 

 the instrument (Fig. 6). Moreover, the depth 

 reading is likely to decrease as the speed of 

 the ship increases. A third dial indicator at 

 the base of the instrument is connected with the 

 scanning mechanism which prints temperature con- 

 tours on the upper part of the chart and shows 

 the temperature currently being plotted. 



The recorder uses the helical-drum-and-blade 

 principle and writes on electrosensitive paper 

 such as Westrex Timemark Wo. 118 or Westrex 

 Wo. hk. It can accommodate rolls of paper 19 

 inches wide and 400 feet long. The paper speed 

 may be varied from 2 to 12 inches per hour but 



the most satisfactory speed for presenting 

 internal waves is approximately 6 inches per hour. 

 At this speed a ^00-foot roll should last approx- 

 imately 33 days . 



Several difficulties were experienced with the 

 temperature contours due to shorts or open cir- 

 cuits in the harness and connecting leads. Other 

 troubles in the recorder were caused by skewed 

 paper feed, burning of paper, shorts in the cir- 

 cuit, smudging of records and improper scanning 

 of the input resulting in flat isotherms. 



Most of the difficulties were eliminated by 

 proper tuning, adjustments and replacement of 

 parts . One improvement was in the change from 

 Westrex Wo. kh paper to Westrex Timemark Wo. 118 

 paper which gave a better quality of trace and 

 reduced handling and recording smudges. Malfunc- 

 tions still occur but sufficient spare parts now 

 insure a successful cruise. 



Beeorder Schematics 



The thermistors are arranged in an array. Each 

 thermistor forms one arm of a voltage divider 

 similar to those used at USWEL on other tempera- 

 ture measuring devices.-' The voltage at the 

 junction of any thermistor with its load resistor 

 is the analog function of the temperature of that 

 thermistor. Several such thermistors equally 

 spaced on the chain produce analogs of temperature 



56 



