44 C. Abbe—Nebule of Herschel’s Catalogue. 
Having computed the right ascensions and declinations of the 
south poles of the fifty-nine nebule in question, as given in 
columns six and seven of the accompanying table, I have also 
tila them upon equal surface charts similar to those used by 
essrs. Proctor and Waters, on which also have been drawn 
the limits of the Milky Way as given by those same gentlemen, 
according to Heis and Herschel. Owing to the fact that the 
unresolved nebule are, as a rule, far more numerous near the 
poles of the Milky Way than elsewhere, it follows at once that 
the greater number of the nebule now under consideration are 
near these poles, and therefore our poles of rotation, if we may 
presume to use that term, lie near the Milky Way itself: buta 
careful enumeration shows us that in the northern hemisphere 
these poles lie to the southward of the central portion of the 
Milky Way, while in the southern hemisphere the reverse holds 
good; in fact, there exists a media] plane about which the poles 
of these nebule cluster, and which is itself inclined to the 
plane of the Milky Way at an angle of about 80°, so that if the 
north pole of the Milky Way be in right ascension 12 h. 45 m. — 
and declination 30°, the pole of the plane near which the rota _ 
tion axes of the nebule lie will have about the same right 
ascension, but a declination of about 60°. Numerically expressed, — 
this latter plane is so situated that of fifty nine nebule twenty- _ 
nine have their axes inclined to it by less than 10°, and forty- 
two have their axes inclined by less than 20°. . 
It is, I conceive, quite desirable that we should, on the 
one hand, have more accurate determinations of the position 
angles of these extended and ray-like nebule, and that, on the 
other hand, the reversion spectroscope of Zéilner should be — 
applied to determine whether or no they be really in a state of © 
rotation. 
By adopting some average value for the oblateness of the — 
spheroids, that appear to us as elliptical or oval nebule, it will 
be possible to obtain a certain approximate estimate of the — 
probability that the plane here determined has some bearing — 
upon the general question of the arrangement of the three or four — 
thousand known nebule (the clusters being included); butsuch — 
a computation involves too much of hypothesis to be of interest — 
at present. ; 
It may then in general be stated, that so far as we are able — 
to determine the positions of planes of rotation among the 
nebulz, they do not show any such tendency to agree with each — 
other as is shown in the orbits and equators of the major plan- 
ets of the solar system; that, on the contrary, they are inclined at — 
all possible angles to each other, but have this remarkable — 
feature, that their mutual nodes cluster about a point in right — 
ascension 12 h. 45 m. and north declination 60°. 
