282 Permanence of the Rutherfurd Photographic Plates. 



Final Table of Discordances, 



RUTHERFUED MEASURES minus NeW MEASURES. 



Star. 



Plate 10. 



Plate 18. 



Plate 22. 



Plate 24. 



Means. 



Mag. 



Angle. 



Dist. 



Angle. Dist. 



Angle. 



Dist. 



Angle. Dist. 



Angle. 



Dist. 



A 34 



0.00 



— 0.12 



— 0.24 — 



.21 



+0 



/ 

 07 



H-0 



"26 



— 0.20 j — 0.02 



— ^'09 



— .02 



7.2 



i8 m — .06 



— .06 \-\- .12 



+ 



•o.S 



— 



08 





•34 



— 



.14- 



.02 



—.04 



—.09 



6.3 



A 12 



— .01 



— .18 + .40 



+ 



.14 



+ 



16 



— 



.10 



-f 



.27 



+ 



.1.3 



+.20 



.00 



7^5 



A 22 



— .04 



+ -27, 



— .06 



— 



.08 



— 



06 



+ 



• iq 





.04 



+ 



.06 



—•05 



+.11 



7.0 



A 24 



— .02 



+ .16 



.00 



+ 



•30 



— 



13 



+ 



.10 



+ 



.07 



+ 



•30 



— .02 



+ .22 



7.0 



A 28 



+ .08 



— .fo 



+ .18 



— 



.13 



— 



12 



— 



• 13 



— 



.14 



— 



•43 



.00 



— .20 



7.0 



A 30 



— .02 



— .01 



- .45 H- 



.08 



+ 



17 



— 



.01 



— 



•17 





.00 



— .12 



+.02 



8.4 



A 39 



+ .41 



+ .03 



+ .14 



— 



.18 



+ 



39 



H- 



.02 



+ 



.20 



— 



.01 



+.28 



—.04 



7-7 



A 34 



^o'i4 



— o''i5 ' 















1 





// 



+.14 



—•15 



7.2 



18 m 



+ -03 



— -17 i 















1 





+.03 



—.17 



6.3 



A 5 — .26 



+ .06 























—.26 



+ .06 



9.1 



A 6 — .05 



+ .03 





















—■05 



+ •03 



9.0 



A II + .04 



+ .06 



■ 1 

















1 +.04 



+ .06 



9-1 



A 26 ;+ .19 



+ .12 



















+.iq 



+.12 



9.0 



A27 + .03 



+ -03 





















+.03 



+.03 



8.5 



A 36 — .26!+ .02 





















—.26 



4.02 



8.5 



If we regard the numbers iii the above Table as residuals we 

 get by the formula 



V 



n — I 



the values : 



r = ± o" . 1 6, for the distances, 



r r= zb o" . 19, for the position angles. 



As these numbers involve the uncertainty of both the old and the 

 new measures, we may draw the conclusion that the positions of 

 the individual stars on the plates are determined by either set of 

 measures with a mean error which will not differ much from O'^.l. 

 We may further conclude that measures of the Rutherfurd 

 plates made at the present time will furnish results practically 

 identical with those that would have been obtained if the plates 

 had been measured twenty years earlier. 



