270 Permanence of the Rutherfurd Photographic Plates. 



order to get the scale correction, which must be added to the 

 measured coordinate. This factor is computed by dividing the 

 quantity in the column " Excess over adopted mean " by the 

 quantity in the adjacent column headed " Diff." 



Computation of Scale Correction Factors. 



Plate. 



Coor- 

 dinate. 



Rot'n 



Nos. 



Star's Coordinate, and Angle 

 Correction. 



Diff. 



Excess 



over 



Adopted 



Mean. 



Corr'n 



Factor. 



Xio* 



A 34 



18 m 



I6 



16/ 



18 



22 



24 



X 



X, rev. 



y 



y, rev. 



X 



X, rev. 



y 



y, rev. 



X 



X, rev. 



y 



y, rev. 



X 



X, rev. 



y 



y, rev. 



X 



X, rev. 



y 



y, rev. 



133,134 

 151,152 

 142,143 

 160,161 



177,178 



195,196 

 186,187 

 204,205 



1,2 

 27,28 

 10,11 

 36,37 



45,46 

 63,64 

 54,55 

 72,73 



89,90 

 107,108 



98,99 

 116,117 



+37-3767 

 +37-3740 

 — 26.9182 

 — 26.9152 



+37-3770 

 +37-3780 

 — 26.9202 

 — 26.9122 



+37-3343 

 +37-3326 

 —26.9846 

 — 26.9810 



+37-3393 

 +37-3384 

 —26.9479 

 —26.9528 



+37-3296 

 +37-3314 

 —26.9631 

 —26.9622 



— I 

 



— 4 

 



— I 



— I 

 + 2 







+ 3 

 + 10 



— 2 

 + 9 



— 3 



— I 



— 7 

 + 4 



+10 

 

 



— 2 



—34.4636 

 —34.4680 

 +48.7850 

 +48-7859 



—34-4656 

 —34.4691 



+48.7837 

 +48.7912 



—34-3981 

 —34-3955 

 +48.8400 

 +48.8404 



—34-4183 

 —34-4193 

 +48.8156 



+48.8137 



—34.3932 

 —34.3936 

 +48.8246 

 +48.8281 



+ 2 

 



+ 3 

 



+ 2 

 + 2 



— 2 

 



— 5 

 —19 



+ 2 



— 8 



+ 5 

 + 2 

 + 7 



— 3 



—19 

 

 



+ 2 



71.8400 

 71.8420 



75.7039 

 75.7011 



71.8423 

 71.8468 

 75-7035 

 75-7034 



71-7332 

 71.7310 

 75-8250 

 75-8197 



71-7568 

 71-7574 

 75-7649 

 75-7658 



71-7257 

 71-7250 

 75-7877 

 75-7907 



—.0050 

 —.0030 

 — -0013 

 — .0041 



— .0027 

 +.0018 

 — .0017 

 — .0018 



+-0013 

 — .0009 

 +-0050 

 —.0003 



— .0004 

 +.0002 

 — -0043 

 —.0034 



— ,0002 

 — .0009 

 — .0029 



+ .0001 



+.70 

 +.42 

 +-17 

 +.54 



+.38 

 —•25 



+ .22 

 + -24 



—.18 



+.13 



—.66 



+.04 



+.06 

 —-03 



+-57 

 +-45 



+-03 

 +.13 

 +-38 

 — .01 



8- The foregoing calculations put us in possession of all the 

 materials needed for the reduction of the measures of the several 

 stars treated in the present research. The following Table con- 

 tains the computation of the final adopted coordinates of all these 

 stars. The corrections applied in the Table to the mean measured 

 coordinates are the angle correction already explained, and the 

 scale correction. This latter is obtained, as we have already 

 stated, by multiplying the correction factor contained in the last 

 column of the preceding Table by the coordinate whose correc- 

 tion is sought. The final adopted values in the last column are 

 simply the means of the corrected results, as given in the preced- 

 ing column for the direct and reversed positions. 



