Test Results 



The negatives for test B were read only 

 once because of the short time available . Sim - 

 ilarly, the negatives for positions 1, 2, 3, 7, 8 

 and 9 of test A. were read only once. The re- 

 sults are listed in table 1. 



Figure lT>»niust ration abovlDg general locetton of poeltlono ^1 throu^ #9 a 

 baoe for testo Ai , A2, and A3.. Meat of the Tcrtlcel grid llneo 

 have been ooltted to elmplify the stetcb. 



The negatives of positions 4, 5 and 6 

 (the positions of the bar on the orientation line 

 of tests A , A , and A ) were read 5 times by a 

 first reader. The same negatives of test A. and 

 A were read three times and those of test A,, 

 2 •^ 



read twice by a second reader. Tlie results are 



listed in table 2 . 



Table 1 shows that in test A, the range 

 of the errors for all positions was from -0.01 to 

 +0.04 centimeters. In test B the range of the 

 errors for all positions was from -0.03 to -t-0.04 

 centimeters. These results indicate that the 

 error for a subject of any length lying anywhere 

 on the grid will not be radically different from a 

 subject of any other length lying anywhere along 

 the orientation line. 



The range of all the errors shown in 

 table 2 is from -0.05 to -1-0.05 centimeters in- 

 dicating that the positions of the two cameras do 

 not change enough from one assembly to the next 

 to cause an error that greatly exceeds the toler- 

 ance limits of -1-0.05 centimeters. The range of 

 errors for Reader No. 1 is -0.05 to -K).05 centi- 

 meters while the range of errors for Reader No . 2 

 is -0.02 to +0.05 centimeters. In general, the 

 errors obtained by Reader No . 2 were well on 

 the positive side, since only 2 of the 24 readings 



TsUa 1.— IMMlt* or t«*t Aj ■ 



1 iMt fi. All *mli»* K 



TBhljt 2.»ReMlt. for pMltLou ^, 3. and 6 oT t^wtu Aj, 

 e«Dtalii. tta. c^vuted Im^^ oT b tnr that 1. t 

 loot' 1%— error A dlff.TV.ce betireen Uie c^ 

 l.^tb 1. aiela.m 1a par.oU«al. . All ..lue. 



A2f ..d Ai. Ikch e.11 

 letttOl; 2S.20 emtlMUra 



obtained by this reader were negative. On the 

 other hand, Reader No. 1 had 18 negative read- 

 ings out of 45 . Though neither reader had any 

 errors that exceeded -MD. 05 centimeters (when 

 rounded to two places) the results indicate that 

 there is a significant difference between readers. 

 Analyzing table 2 by position, it is seen that 

 while the errors for position 4 and 5 are com - 

 parable, those of position 4 tend more toward 

 the negative direction than 5. The errors for 

 position 6, on the other hand, tend more toward 

 the positive direction than position 5. This gen- 

 eral pattern is shown more clearly in the read- 

 ings taken by Reader No . 1 . 



In summary, the results indicate that 

 (1) the magnitude of the error for a subject of 

 any length lying anywhere on the base is in the 



12 



