Permanence of the Rutherfurd Photographic Plates. 281 



Plate 24. 



star. 



Mag. 



Position Angle. 



Old Measures minus New Measures. 1 



Old Measure. 



New Measure. 



Obs'd. 



Corr'd. 



In Sec. 



A 34 

 i8 m 



A 12 

 A 22 



A 24 

 A 28 

 A 30 

 A 39 



7.2 

 6.3 

 7-5 

 70 

 7.0 

 7.0 

 8.4 

 7-7 



I 25° 50 23" 

 324 50 28 

 347 49 5 

 175 38 27 

 9 49 34 

 161 4 28 

 117 39 16 

 61 3 15 



50' 22" 

 50 19 

 48 9 



38 20 

 48 53 



4 21 



39 18 

 2 43 



+0 01 

 +0 09 

 +056 

 +0 7 

 +0 41 

 +0 7 

 -0 2 

 +0 32 



// 



—17 

 — 9 

 +38 

 — II 



+23 

 — II 

 — 20 



+ 14 



— 0.20 

 — -14 



+ .27 



— .04 

 + .07 



— -H 



— -17 

 + .20 









Distance. 





Old Measures minus 



Star. 



Mag. 









New Measures. 



Old Measure. 



New Measure. 



New Meas. 







A 34 





Ru. Scale. 



Millimeters. 



Ru. Scale. 



Scale. 



In Sec. 



7.2 



86.9350 



46.0503 



86.9358 



— .0008 



— 0.02 



18 m 



6.3 



112.7509 



59-7251 



II2.7517 



— .0008 



— .02 



A 12 



7-5 



52.9480 



28.0443 



52.9432 



-i-.oo48 



+ .13 



A 22 



7.0 



25-9598 



13-7499 



25.9577 



+.0021 



+ .06 



A 24 



7.0 



22.4990 



11.9121 



22.4882 



+.0108 



+ .30 



A 28 



7.0 



93-9391 



49.7681 



93-9544 



— -0153 



— -43 



A 30 



8.4 



61.7977 



32.7345 



61.7976 



+.0001 



.00 



A 39 



7-7 



103-3731 



54-7575 



103.3736 



—.0005 



— .01 



SUD 



a 



560.2026 



296.7418 









10. The final result of the whole research is contained in the 

 following Table, which requires little or no explanation. It may 

 be well to repeat, however, that the discordances in position an- 

 gle have been corrected by a constant, so as to make the sum of 

 the discordances zero for any given plate. This is equivalent to 

 correcting the orientation of the plate in its holder, so as to make 

 it the same for the old and new measures. The position angle 

 discordances were turned into arc of a great circle, by multiplying 

 each discordance by the sine of the distance of the star in ques- 

 tion from the central star. This operation has caused the sum of 

 the position angle discordances to difier somewhat from zero in the 

 Table. The distance discordances have also been computed 

 in such a way as to make their sum zero. 



