14 
The temperature bridges were adjusted so as to read from 9°C to 
19°C, and the pressure bridge adjusted so as to produce the follow- 
ing five ranges which are given in feet: 0-100, 50-150, 100-200, 
150-250, and 200-300. Another strip chart recorder was used to 
record continuously the relatively fast temperature fluctuations of 
one uncoated thermistor. This single-channel recorder was a 
Minneapolis-Honeywell Model 153 x 16, potentiometer type with a 
1/4 second full scale pen speed, and a range of 0-10 millivolts. 
DIGITAL DATA RECORDING SYSTEM. Since data analysis on a 
digital computer was necessary, these records on strip chart 
paper had to be transferred to an input system compatible with the 
computer. This was done by transferring the temperature, depth, 
and associated time readings onto punched cards. However, this 
job is extremely tedious and laborious, which was one of the main 
reasons for the acquisition of a digital data recording system that 
could provide the output directly in punched tape form having a 
format compatible with the input system of the CDC 1604 computer. 
Before describing this new system, it should be noted that the sys- 
tem involving the strip chart recorders is still used, but primarily 
as a visual monitor. Thus, it is used for determining the desired 
running depth based on the temperature structure. 
The block diagram of the digital data recording system is 
shown in fig. 8. The bridges were built at this Laboratory; the 
associated digital system was built according to our specifications 
by Electro-Instruments, Inc.* Most of the components are well 
tested, off-the-shelf items which, in general, were only slightly 
modified to fit into the over-all system. In general, the system 
sequentially records (on punched tape and/or printed tape) the 
temperature of 26 thermistor sensors, depth, and associated time 
of day. Listed below are some of the main features, functions, 
and limitations of the components: 
1. Temperature sensors -- 26 coated or thermally lagged therm- 
istor units. 
*Electro-Instruments, Inc., 8611 Balboa Ave., San Diego 11, Calif. 
