OF NEBULAE AND CLUSTERS OF STARS. 
11 
observer, to advertise him of what sort of object he may expect to see, the following 
scale may be taken as conveying a general idea of the magnitudes intended by the con- 
ventional words used. Thus, a round nebula of 3" or 4" in diameter would be called 
extremely small ; 
one of 10" or 12", very small-, 
20" or 30", small , or considerably small ; 
50" or 60", pretty small , or pretty large; 
3' or 4', considerably large , or large ; 
8' or 10', very large; 
20' and upwards, extremely large. 
In estimating clusters of stars (that is to say, of well separated and scattered stars) a wider 
acceptation must be understood, so that, for instance, a cluster of only 1' in extent would 
be considered extremely or very small; one of 15' or 20' large , and one of 30' or 40' very 
large. This amplification of scale, however, must not be held applicable to those 
resolved or resolvable clusters of a “ globular ” character marked in the descriptions 
as 0, which must be understood as belonging to “ nebulae ” and not to “ clusters,” so 
far as the conventional terms used in the descriptions are concerned. I should observe 
also, that when in making out the average appropriate phrase in size I have found any 
extravagant discordance between the estimate in words and that in figures, as, for 
instance, where a nebula has been described in words as very large , and the diameter 
then set down as 2', a compromise has usually been made, and the word modified, as, for 
instance, to large or considerably large. 
The abbreviations employed in the column of descriptions and elsewhere, in the notes, 
&c., are as follows : — 
ab. 
about. 
ch. 
chevelure. 
aim. 
almost. 
com. 
cometic. 
am. 
among. 
cont. 
in contact. 
app. 
appended. 
C. 
Compressed. 
att. 
attached. 
Cl. 
cluster. 
Auw. 
Auwers. 
C.G.H. 
“ Results of observations, &c. at the Cape of 
A.S.C. 
Astronomical Society’s Catalogue. 
Good Hope.” 
b. 
brighter. 
C.H. 
Miss Carolina Herschel. When it occurs in 
bet. 
between. 
column 4 it indicates that the object was 
biff. 
binuclear. 
discovered by her. 
bn. 
brightest towards the north side. 
d. 
diameter. 
bs. 
brightest towards the south side. 
dist. 
distance. 
bp. 
brightest towards the preceding side. 
distant. 
bf. 
brightest towards the following side. 
dif. 
diffused. 
B. 
Bright. 
diffic. 
difficult. 
Br. 
Brisbane (Sir T.’s) Catalogue of Stars. 
D. 
double. 
Bo. 
Bode. 
D’Arr. 
D ’Arrest. 
B.A.C. 
British Association Catalogue. 
A. 
Dunlop. 
c. 
considerably. 
def. 
defined. 
CO. 
coarse, coarsely. 
e. 
extremely. 
c 2 
