with Remarks on the Construction of its different Parts. 125 
The Curvature of the Tail. 
The shape of the tail with respect to its curvature is gene- 
rally considered only as it relates to the direction of the motion 
of the comet; it is nevertheless subject to variations arising 
from causes that will be noticed in the next article, but which 
are not taken into the account of the following observations. 
The 9th and 10th of September the curvature of the tail 
was very considerable. 
The 18th, I remarked, that towards the end of the tail its 
curvature had the appearance as if, with respect to the motion 
of the comet, that part of the tail were left a little behind the 
head. 
The 17th of October the tail appeared to be more curved 
than it had been at any time before. 
Dec. 2, the flexure of the curvature of the tail, contrary to 
its former direction, was convex on the following side. 
The general Appearance of the Tail. 
On account of the great length and breadth of the tail of 
the comet, a night glass with a large field of view is the most 
proper instrument for examining its appearance. Mine takes 
in 4 0 41'. 
By viewing the comet with this glass I found the tail to be 
inclosed at the sides by the two streams which I have de- 
scribed as the continuation of the bright arch, or envelope 
surrounding the head. 
Sept. 18 , 1 observed that the two streams or branches aris- 
ing from the sides of the head scattered a considerable portion 
of their light as they proceeded towards the end of the tail, 
