READING TELESCOPE 



The 20X erecting telescope (fig. 3) can focus to 

 a minimum distance of 10 inches. At a 13-inch distance 

 its field is about 1 inch^ and the main and auxiliary ther- 

 mometers can be read without lateral adjustment. The 

 assembly of telescope and traveler was aligned to make 

 the telescope precisely perpendicular to the axis of the 

 thermometers which eliminates error due to parallax. 



THERMOMETER RACK 



Two disks of 1/ 2-inch-thick Micarta, held 15 

 inches apart and rigidly fastened to a stainless-steel shaft 

 passing through their centers, form the thermometer rack 

 (fig. 4a). Spring-loaded, rubber-faced cups are positioned 

 at the perimeter of one disk with matching rubber-faced 

 screw-adjustable cups on the other. The assembly will 

 hold 24 deep-sea reversing thermometers, and smaller 

 holes are provided for supporting the same number of 

 ordinary stem thermometers. Both ends of the shaft have 

 a coupling designed to engage a slotted yoke on the lower 

 end of a drive shaft coming through the lid from the Geneva 

 movement. Power supplied by a 1/10-hp reduction-gear 

 indexing motor on the tank lid rotates the rack to bring 

 each thermometer in front of the reading telescope. 



In the original design, reversal of the thermometer 

 rack was accomplished by throwing a "Reversing-Start" 

 switch followed by a "Reversing" switch on the control panel. 

 Problems were encountered in reversing. To overcome 

 these problems, a solenoid-actuated locking plunger was 

 installed to engage one of the notches of the detent wheel 

 at the precise moment the motor current is cut off by the 

 rack driving lug (fig. 4a). Because the microswitch and 

 solenoid system which lifted the indexing yoke was exposed 

 to the humid conditions present in the tank, its action was 

 erratic with occasional mechanical binding and electrical 

 failure. This assembly was removed and a simple, manually 

 operated, yoke release lever (fig. 2) installed to perform the 

 same function. Its retractable handle is just above the tank 

 lid within easy reach of the operator. As a safety feature a 



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