384 ANNUAL OF SCIENTIFIC DISCOVERY. 



of its previous discovery in Italy. It was seen by Mr. H. P. Tuttle, on the 

 evening of the 28th of June, and an accurate determination of its place was 

 made on the same night at the observatory of Harvard College. On the 

 29th, it was detected by H. M. Parkhurst, Esq., of Perth Amboy, N. J. ; and 

 on the 1st of July, by Miss Mitchell, of Xantucket. 



Three geocentric positions, obtained on the 7th, llth, and 13th of June, 

 furnished Donati with the means of computing approximate elements of the 

 comet's motion, from which its interesting character was quickly recognized. 

 Considerable difficulty was experienced in fixing the precise time of perihe- 

 lion passage, a most necessary condition in predicting its path as seen from 

 the earth. While in other respects the results deduced by various com- 

 puters were sufficiently accordant, they showed wide discrepancies in desig- 

 nating the place of the comet in the orbit. By the middle of August, how- 

 ever, its future course, and great increase of brightness in September and the 

 early part of October, had been ascertained with entire certainty. 



Up to this time it had remained a faint object, not even discernible by the 

 unassisted eye. It was distinguished from ordinary telescopic comets only 

 by the extreme slowness of its motion, in singular contrast with its subse- 

 quent career, and by the vivid light of the nucleus; the latter peculiarity 

 was of itself prophetic of a splendid destiny. 



Traces of a tail were noticed on the 20th of August, and on the 29th it was 

 seen with the naked eye as a hazy star. For a few weeks it occupied a posi- 

 tion in the heavens where it rose before the sun and set after it, becoming 

 thus a conspicuous object both in the morning and evening sky. This cir- 

 cumstance gave rise to the erroneous notion that two different comets had 

 appeared. The statement, which was widely circulated, that this was the 

 return of the comet of 1264 and of 1556, supposed by some to be identical, 

 is equally incorrect. If it has ever before been seen by man, it must have 

 been far back in history, since the most recent computations assign a time 

 of revolution of about twenty -four hundred years. 



On the 6th of September was first noticed the curvature of the tail, which 

 subsequently, at the time of its greatest expansion, became one of its most 

 impressive features. It is remarkable that this peculiarity should have been 

 strongly enough exhibited to be distinguished at the above date, when the 

 earth was close to the plane of the comet's orbit. The observation cannot, 

 in fact, be reconciled with the commonly received opinion that the curvature 

 of the tail lies in the plane of motion about the sun. 



On the 20th, the first of a series of extraordinary phenomena manifested 

 itself in the region contiguous to the nucleus. A crescent-shaped outline, 

 obscure and very narrow, was interspersed, like a screen, between the nucleus 

 and the sun; within this, instead of a softly blended nebulous light, indic- 

 ative of an undisturbed condition of equilibrium, the fiery mass was in a state 

 of apparent commotion, as though upheaved by the action of violent inter- 

 nal forces. On the 23d, two dark outlines were traced more than half way 

 round the nucleus, and on the next evening still another. Each of these 

 was evidently the outer boundary of a luminous envelope, the brightest be- 

 ing that nearest the nucleus. 



On the 25th four envelops were seen, and others were subsequently 

 formed, almost under the eye of the observer, their motion of projection 

 from the nucleus being evident from night to night. The rapidity of their 

 formation, and the enormous extent to which they are ultimately expanded, 

 are phenomena extremely difficult to explain. The scene of chaotic con- 



