Objective Screw Thread. 



231 



Length of Thread on Objective, ' 1 25 in. ( = 3 • 1750 mm.). 



Plain Fitting above Thread of Objective, 01 in. (= 2-5400 mm.) 

 long, not to exceed 0*759 in. (= 19*2784 mm.) in diameter. 



Length of Screiv of Nose-piece to be not less than 0*125 in. 

 (= 3-1750 mm.). 



Limits. 



Nose-piece : — 



Gore Diameter of Thread {A) not toexceedO • 7674 in. ( = 19 ■ 4918 mm.), 

 or be less than 0*7644 in. (= 19*4156 mm.). 



Full Diameter of Threat (B) not to exceed ■ 803 in. ( = 20 * 3960 mm.), 

 or be less than 0*800 in. (-20*3198 mm.). 



- /J 



B —+•- 



■/ 



*- 



I2S 



Fig. 29. 



Objective : — 



Full Diameter of Thread (C) at top of thread not to exceed ' 7982 in. 

 (= 20*2741 mm.), or- to be less than 0*7952 in. (20*1979 mm.). 



Core Diameter of Thread (D) at bottom of thread not to exceed 

 0*7026 in. (=19*3699 mm.), or to be less than 0*7596 in. 

 (= 19*2937 mm.). 



