REVIEWS—DONATI’S COMET. 63 
supposition inconsistent with the observations, and we may add that 
this result of a constant deviation being throughout preserved, is a 
priori very unlikely. Some remarkable irregularities presented them- 
selves, however, in this comet. Shortly after the first appearance of 
the tail, the curvature it assumed was in the direction opposite to that 
above stated and which it afterwards had, and at the same time the 
following branch was brighter than the preceding one; observations 
so abnormal that one would have been inclined to refer them to a de- 
lusion of the observers, had they not been strangely confirmed by a 
recurrence of the same phenomenon, not long before the disappear- 
ance of the tail as the comet was going away. There was also noticed 
for some time a change in the curvature of the outlines, both branches 
being bent inwards about the middle of their lengths, making the tail 
somewhat of a lozenge shape, or like a willow-leaf. In connection 
with this may be noted the irregular termination of the inner branch 
as it gradually faded into a shapeless mass of light. We will here 
quote the observations themselves. 
Oct. 8, Powriu at Mapras.—“ Outline of envelope ragged, the 
tail reaching a little beyond a Coronz Borealis. On the lower side 
the light shades off almost imperceptibly ; on the upper, though rag- 
ged, it terminates comparatively abruptly. The darkness down the 
envelope scarcely so clear as before. Nucleus about as bright as Mars 
ora Lyre. The shape of the envelope bears a resemblance to a pen, 
being narrow at the head, and after a short space suddenly spreading 
on the lower side like the feather of a quill.” 
Oct.8, Wrens at TreTIRE, EnG.—“ The general impression of this 
(the under) side of the tail was that of spreading out like a feather, as 
compared with the more definite aspect of the convex edge.” 
Oct. 10, Same observer.—‘ The curvature appeared regular as far 
as a line Joining a Corone and ¢ Herculis, or perhaps a little farther ; 
thence a fainter ray of considerable breadth was deflected at a large 
angle, perhaps 60°, as far as the stars of Quadrans Muralis, This 
portion was very feeble, but certain, and looked quite like a scattered 
and abandoned vapor.” 
And special note may be taken of the following : 
Oct. 8, Seccui at the Cottegio RoMano.—‘“Si conserva pure 
all’ osservatorio un disegno della cometa come era visibile ad occhio 
nudo, ove si ebbe cura di far rilevare la forma curva dell’ estremitd 
della coda, e quella specie di materia sparsa che accompagnava, irre- 
golarmente diffusa che si potrebbe credere affatto useita dalla sfera d’ 
