478 Royal Society : — 



eclipse, previous to those printed off for general distribution by 

 Senor Aguilar. I was agreeably surprised to rind that the photo- 

 graph of the first phase of totality showed not only this prominence 

 very distinctly, but also other details, presently to be described, which 

 were quite invisible in Senor Aguilar' s copies. I had in fact experi- 

 enced some difficulty in comparing measurements of my photographs 

 with those of Senor Aguilar' s, on account of the indistinctness (wool- 

 liness) of the latter, which I have attributed to Padre Secchi's tele- 

 scope not having followed the sun's motion perfectly. A careful 

 examination of the prints in Padre Secchi's possession has, however, 

 convinced me that this was not the case during the period of expo- 

 sure of the first negative ; for 1 have been able to identify with a mag- 

 nifier many minute forms which could only have been depicted by the 

 most perfect following of the sun's apparent motion. For instance, 

 my statement that the prominence H (the fallen tree) was not seen 

 from having been mixed up with the prominence Gr, is not appli- 

 cable to Padre Secchi's copy of the first phase of totality, for in it 

 every detail of the fallen tree can be made out. 



On expressing to Professor Secchi my surprise at the great discord- 

 auce between the copy of the first phase of totality sent to me by 

 Senor Aguilar and that of the same phase in his possession, I was 

 informed that after a few positive prints had been taken from the 

 then unvarnished negative, it was strengthened by the usual photo- 

 graphic process with nitrate of silver. This I look upon as an unfor- 

 tunate mistake, as the images of the prominences were increased and 

 their details hidden, and the beauty of the negative for ever lost. 



It occurred to Padre Secchi and myself-that although there was no 

 hope of procuring more satisfactory prints from the original negative 

 of the first phase of totality, yet some advantage would arise from 

 taking an enlarged negative from the positive print in his possession, 

 although it could not be expected to yield as perfect an impression 

 as might have been obtained by enlarging from the original photo- 

 graph. The enlargement has been successfully accomplished in my 

 presence ; and although Padre Secchi will take such means as he 

 may think proper to make known the results of comparisons he may 

 make between my photographs and his own, it will not be out of 

 yjlace for me to add a few remarks by way of appendix to my paper. 



Taking the prominences in the order in my index map, Plate 

 XV. :— 



Prominence A (the cauliflower or wheatsheaf) has the same form 

 in Padre Secchi's photograph as in mine. It extends considerably 

 less in height above the moon's edge in this copy than in that printed 

 off from the strengthened negative (Senor Aguilar's copy) ; the bright 

 points of the two branching streams which issue from the summit 

 towards the North are well depicted in the Secchi photograph, but 

 not the fainter parts. 



There exists a faint indication of the minute prominence B in 

 the S. photograph. 



The convolutions of the prominence C (the floating cloud) are 

 seen in the S. photograph, and its form coincides absolutely with 



