in the table of oceanographic data have a probable error of about 

 ±0.01° C. 



The new TD mentioned above is a self-contained instrument of 

 rapid response which traces a continuous curve of temperature against 

 depth on a scale of approximately 11.2 mm. per degree C and 13.6 

 mm. per 100 meters. The temperature scale accommodates 35 centi- 

 grade degrees and the depth range is limited to 1,800 meters. The 

 temperature element is an electrical resistance thermometer which 

 controls the axial position of the pencil carriage. The depth element 

 is a helical Bourdon tube which controls the angular position of the 

 drum holding the record chart. The movements of pencil and drum 

 are the electronically magnified changes in balance of the alternating 

 current thermometer bridge and of the changes in shape of the Bour- 

 don tube followed up by means of a linear differential transformer 

 (Schaevitz). A frequency of 400 cycles is used in the servo balancing 

 systems and a 12 volt lead nonspUl battery is the primary power 

 source. 



The instrument is made up in 3 sections which are assembled in a 

 steel pressure case 6 feet long and having an outside diameter of 8 

 inches and a wall thickness of three-eighths of an inch. The assembled 

 instrument weighs 337 pounds in air and about 200 pounds in water. 

 The forward or lower section contains the battery which must be 

 removed periodically for charging. The rear or upper section contains 

 the recording drum and must be removed, at least partially, to change 

 the record chart. The center or control section need be removed only 

 infrequently. Figiu-e 12 shows the three sections assembled outside 

 the pressure case. A block diagram of the instrument is shown in 

 figure 13. A more detailed description is contained in Woods Hole 

 Oceanographic Institution's unpublished report of February 1953 

 "The Deep Electronic Bathythermograph" by Karl E. Schleicher 

 (Reference No. 53-10). 



In use the TD was shaclded, in lieu of a sinker, to the lower end of 

 the oceanographic wire rope to which the Nansen bottles and reversing 

 thermometers were attached. As the instrument had been used on 

 only a small number of lowerings previously, no standard handling 

 procedure had been developed. Because of its weight and size the 

 TD was very difficult to control in launching it from and returning 

 it to its cradle on deck. On numerous occasions the side of the case 

 hit the side of the ship with varying degrees of impact resulting in 

 displacements of the atmospheric pressure position of the Shaevitz 

 transformer core. On one occasion the thermal element hit the A 

 frame and this probably was responsible for the eventual failure of the 

 instrument when it filled with water through the thermal element. 

 In all, 26 casts were made. Many of these were trials after unsuccess- 

 ful attempts to remedy faults. As a result 14 traces were obtained 



4? 



