210 



Prof. C. Pritchard. 



Table VI. — Discordant Measures of the Six Stars on the Disturbed 

 Film. Plate IV. 



Number of plate. 



Atlas. 



Pleione. 



Star 29. 



Plate I 



u II 



„ HI 



„ IV discordant . . . 



1391*14 

 1391 -46 

 1391 -42 



1402 - 67 



1403- 50 

 1403 -08 



1202 -23 

 1202 -29 

 1202-31 



1391 -34 



1403 08 



1202 -28 



1391 77 



1403 -95 



1203 -04 



Number of plate. 



Star 31. 



Star 32. 



Star 33. 



Plate I 



„ II 



„ HI 



„ IY discordant . . . 



1806-11 

 1807 -39 

 1806-99 



1832-58 

 1832-89 

 1833 -02 



1678- 39 



1679 - 56 

 1679 -24 



1806 -83 



1832 -83 



1679 -06 



1808-55 



1834-15 



1680 -34 



It may be noticed that the discordances for Atlas and 29 are not so conspicuous 

 as for the remaining stars, indicating that the principal disturbance of the film has 

 taken place in the neighbourhood of 31, 32, and 33. The maximum discordance 

 applies to the Star 31, where it is l'7 ,f ; and the least disturbances applies to Atlas, 

 where it does not reach half a second of arc. 



The accordance of the measures given in Tables IV and V inter se, 

 is quite equal to that exhibited by the measures of the illustrious 

 astronomer of Konigsberg. I confess that, having already had a long 

 experience of the results of repeated measures of distances of spots on 

 the moon as obtained from lunar photographs (" Mem. Roy. Astron. 

 Soc.," vol. 47 (1883)), and being at the same time aware also of Dr. De 

 La Rue's great success in measuring solar photographic images, I was 

 not altogether surprised, but agreeably satisfied by the removal of all 

 doubt and uncertainty. But, in reference to this question, we must 

 not overlook the fact of the generic distinction which exists between 

 the circumstances attending the production of these solar and lunar 

 photographs and these stellar images formed on photographic films of 

 a totally different description, and which latter films do necessarily 

 present difficulties and suspicions not applicable to the former. In 

 the former case the collodion plates were exposed for at most a very 

 few seconds, or even for fractions of a second ; but in the case of the 

 star plates, the exposures last, not only through very many minutes, 

 but the several star images make their appearance, according to their 



