105. At the right rear of the chronometer shelf a terminal strip for the 

 time control cable is mounted. Another terminal strip is mounted on the 

 inside bottom of the chronometer box; the chronometer circuit terminates on 

 this strip „ 



106 „ The Chronometer supplied as station equipment is a standard Navy type 

 Hamilton 12-hour Marine chronometer, designed to run a maximum of 56 hours 

 on a full windings It should be placed into operating service only_ by 

 qualified personnel. Navy procedure for handling, ■winding, and setting a 

 chronometer should be carefully adhered to, A description of this procedure • 

 lies outside the scope of this Maintenance Manual „ 



107o The following three rules must be strictly followed by station personnel: 



1, Never let the chronometer run down; always wind it at regular 

 intervals, preferably once each day 



2, Never touch or interfere with the second hand, Never move the 

 hour and minute hands counterclockwise,, 



3, Never remove the chronometer from its case except for winding. 



Further details concerning this type of marine Chronometer can be obtained 

 from the booklet entitled "Care and Handling of the Hamilton Marine Chronom- 

 eter," published by the Hamilton Watch Company at Lancaster, Pennsylvania, 

 U,ScA<, This booklet is available from the manufacturer on request, 



SHOT ARRIVAL TIME EVALUATOR 



108,. The accuracy with which the source of an explosion signal in a given 

 area of triangulation can be determined depends upon the SOFAR station 

 operator's ability to time the arrival of the peak of each shot. The shot 

 arrival time evaluator (Fig, 27) is designed to enable the operator to do 

 this timing accurately to one tenth of a seconds 



109, The shot arrival time evaluator resembles a slide rule. It has a 

 body of wood with gates on each end. to clamp the paper tape from the graphic 

 level recorder tightly in place* The sliding indicator is of lucite. It 

 has two scales engraved upon it — one for use with 5 mm, /sec, tape speed, 

 and the other for use with 10 mm, /sec, tape speed. Two small metal posts 

 are located at one end of the body. These are designed to fit into the 

 sprocket holes on each edge of the waxed-paper tape, and thus eliminate 

 error due to improper positioning of the tape in the evaluator, 



110, One of the engraved scales on the cursor is labeled 



This scale is used when. analyzing tapes from the "slow-speed" graphic level 



- 25 



