322 



RUDDER TRIALS, U. S. S. STERETT. 



of |-inch chain was secured in the dynamometer with 3 or 4 inches of slack 

 between the grips. The free ends were shackled to the straining heads of 

 the testing machine. The recording gear was rigged exactly as it was to 

 be used on the actual turning trials. 



The procedure during calibration was as follows : — ^Af ter setting up a 

 spring in the dynamometer, and throwing a load on and oflf several times 

 to loosen up the gear, the beam of the testing machine was set at 300 lbs. 



aTl^AKMING HCAO 



|3e& Ot= TSSTlMfe MftCMINE* 



The paper-recordfroU was then started and the load brought up until an 

 exact balance was obtained on the testing machine. The base-line pen was 

 then set to coincide with the tracing of the force-recording pen in this con- 

 dition. This insured a constant, definite reference line which was main- 

 tained for all succeeding^tests for this spring. The load was then increased 

 by steps of 200 lbs. (500 lbs. for springs Nos. 62, 63, and 67) at a uniform 

 rate of the straining-head of .025 foot per minute (.052 foot per minute for 

 the three heavier springs) to the maximum loads shown in the foregoing 



