The Butherfurd Photographic Measures. 131 



Table XYII. — Parallax Equations. 

 Comparison Stars 39 and 6 













Residuals 



Plate. 











Scale. 



Arc. 



1 



1.00.C 



—1.142/ 



— 1.30II 



+3.01=0 



4-0.52 



+".15 



2 



1. 00 



— 1.13 



—1-37 



4-1.92 = 



—0.68 



— .19 



3 



1. 00 



— 1.13 



—1-37 



4-1.84 = 



—0.76 



— .21 



6 



1. 00 



—0.04 



■ — 1.76 



4-5.00 = 



4-2. IO 



4- .59 



9 



1. 00 



+0.88 



—1-43 



4-1.82 = 



-0.29 



.— .08 



10 



1. 00 



+0.89 



—1-52 



4-1.20 = 



—1.05 



— -29 



11 



1. 00 



+0.90 



—1-55 



4-1.27 



—1.03 



— .29 



13 



1. 00 



+0.90 



—1-55 



4-3.27 = 



4-0.97 



4- -27 



15 



1. 00 



+ 1.42 



4-1-73 



— 2.21 =0 



4-0.92 



4- .26 



16 



1. 00 



+1-45 



+ 1. 81 



— 1.16 = 



4-2.09 



4- -59 



17 



1. 00 



+ 1-45 



4-i. 81 



—4.87=0 



— 1.61 



— -45 



18 



1. 00 



+1-45 



4-i. 81 



— 2.30 = 



4-0.96 



4- -27 



19 



1. 00 



4-1.45 



+1.81 



—3.98 = 



— -0.72 



— .20 



20 



1. 00 



+I-45 



+1.81 



— 4.70 = 



—1.44 



= 20.23 



— .40 



Normal Equations. 



4-14.0000x4- 8.80003/ — 1.0700II4- 0.1100 = 



+19.5704 +14.8265 —28.9273 = o 



4-37.o75i —63.9392 = 



Solution. 



In units of 2d dec. place of scale. In Arc. 



IT = 4-1.6054 ±0.2051 n = 4-o // .4497 ±o // .o575 



y = 4-0.2941 ±0.3330 y = 4-o .0821 ±0 .0933 



x = — 0.0694 ±0.3291 x = — o .0194 ±0 .0922 



Scale. Arc. 



Probable error of one equation = ±0.9145 = ±o // .2562 



