Permanence of the Rutherfurd Photographic Plates. 269 



Reduction of Special Standard Measures. 



Plate. 



Coor- 

 dinate. 



Rot'n 

 Nos. 



Scale Reading. 



Diff. 



Angle 

 Corr'n. 



Corr'd 

 Diff. 



Adopted 

 Mean. 



A 34 



18 m 



l6 



16/ 



i8 



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. 



a; 



X, rev. 



2/ 



2/, rev. 



173.174 

 171,172 

 175,176 

 169,170 



173.174 

 171,172 



175,176 

 169,170 



21,22 



23.24 

 19,20 

 25,26 



85,86 

 83.84 

 87,88 

 81,82 



129,130 

 127,128 

 131,132 

 125,126 



28 9624 



101.4077 



96.2734 



34. 1000 



28.9624 



TOI.4077 



96.2734 



34. 1000 



29.2054 



IOI.1554 

 94.9802 

 35.3816 



32.7652 

 97.6076 



93.0331 

 37.3382 



27.9004 



102.4740 



93.9676 



36.4047 



100.8026 



29.5574 



20.5656 



109.8025 



100.8026 



29-5574 



20.5656 



109.8025 



100.9409 

 29.4260 

 19.1614 



III. 2032 



104.5176 

 25.8464 

 17.2642 



113.1101 



99.6263 

 30.7484 

 18.1783 



1X2. 1966 



71.8402 



71.8503 

 75.7078 

 75.7025 



71.8402 



71.8503 

 75.7078 



75.7025 



71.7355 

 71.7294 

 75.8188 

 75.8216 



71.7524 

 71.7612 

 75-7689 

 75.7719 



71.7259 

 71.7256 

 75-7893 

 75-7919 



— 4 

 

 

 



— 4 

 

 

 



— 7 



— 4 

 + 3 



— 7 



+ 7 







— 10 



—14 



+ 7 



— 4 

 

 



71-8398 

 71.8503 

 75.7078 

 75.7025 



71 8398 

 71-8503 

 75.7078 



75-7025 



71-7348 

 71.7290 



75-8191 

 75.8209 



7I-753T 

 71.7612 

 71.7679 

 71.7705 



71.7266 

 71.7252 

 75.7893 

 75.7919 



71.8450 

 75.7052 



71.8450 

 75.7052 



71.7319 

 75.8200 



71.7572 

 71.7692 



71.7259 

 75.7906 



The reductions are continued in the next Table. The numbers 

 in the columns " Stars Coordinate " are obtained from the Table 

 containing the original measures, by simplj^ subtracting the scale 

 reading corresponding to the central star from that belonging to 

 the star in question. In doing this, of course the means of the 

 measures were used, both for the central star and for the other; 

 the very small angle corrections were computed in the manner 

 already explained. The quantity in the column headed " Differ- 

 ence " ought to be equal to the quantity corresponding to it in 

 the column " Adopted Mean " of the preceding Table. A.wy ex- 

 cess has been taken to be caused by a change in the temperature 

 of the scale between the days when the special standard measures 

 and the other measures were made. Such differences are set 

 down in the column "Excess over Adopted Mean." The last 

 column is headed " Correction Factor," and gives the factor by 

 which each of the coordinates as measured must be multiplied, in 



