170 Transactions.— Miscellaneous. 
The blue Planetary Nebula near the Southern Cross.—This object, 
No. 8365 in Sir John Herschel’s Catalogue, is in R. A. 11hrs. 44min., and 
decl. 56° 31'S. The colour of this strange object is a bright unmistakable 
blue. This nebula, like other planetary nebule that have been examined 
in the Northern Hemisphere, gives a spectrum of one bright line. Possibly, 
in a larger instrument, more lines might be seen. It is, of course, 
impossible with my apparatus to determine the position of this line, as 
there are no landmarks, so to speak, to guide one to a decision. It is most 
probable, however, that it is one of the hydrogen or of the nitrogen lines, 
and that this planetary nebula is a spherical mass of one or both these 
gases in an incandescent state. 
a Crucis.—This superb pair of stars, by far the finest in the sky, con- 
sists of two stars, bluish white in tint, and very nearly equal in size, each 
being of the second magnitude. There is a distant six-magnitude com- 
panion, of a sea-green colour, as well as three smaller comites of magni- 
tudes, 121, 14, and 18 respectively. These latter are well seen in the 8}- 
inch reflector, but a small telescope of course does not show them. I have 
made a very great number of measures of the angle of position of this star, 
and having weighted the observations with reference to the state of the 
atmosphere, etc., at the time when the measures were taken, I find the 
angle of position for the year 187877 to be 118:5?. This, by a very singular 
coincidence, is exactly the same angle as that obtained by Powell in the 
year 1863. Herschel gives the angle for 1885-38 as 120-6". I may say 
that, if I had rejected two of my observations, which were made in rather 
bad weather, and which exceeded the average of the rest by 14° and 34° 
respectively, the angle obtained, taken in connection with Powell's and Sir 
John Herschel’s, would have indicated, I believe, a very slow but really 
regular angular motion, in a retrograde direction, since Herschel's time, 
and would, with the measures of distance given below, have convinced me, 
at all events, that a Crucis is a binary star of very long period. The temp- 
tation in such cases to ‘‘ cook one's accounts” a little, to omit taking into 
aecount facts or numbers which do not square with one's own views or 
wishes, is very strong, but the man who cannot resist it had better give up 
science altogether and take to something else in which it is not of vital 
importance that he should tell the truth, the whole truth, and nothing but 
the truth, with regard to his observations. The distance between the two 
stars at the epoch, 1836:36, was 5°65"; in 1863, Powell made it 4-98"; and 
at the end of last month, 1879-75, the distance, a mean of several measures, 
was 4°79". a Crucis is a hydrogen star, but its spectrum is very difficult to 
observe, except in the finest weather. Even then the only lines that I can 
make out are the hydrogen lines, and they are by no means very easy to see. 
