584 NATURE 
With a mirror I should not have found the large 
nebulae in Cygnus, the large nebulosities of Taurus, of 
Cassiopeia, of Aquila, of Orion, and of many other 
regions. I only could find them on the ample field of 
the portrait lens. 
The very small doublets—for instance the small lantern 
enses, which have been used by myself, and afterwards 
yy Prof. Barnard—are in certain cases inferior to larger 
enses. The smaller lenses crowd the nebulous masses, 
found the nebulosities in Taurus, and the America nebula 
for the first time, on plates which were exposed for only 
a very short time. A second way is to use a mono- 
chromatic light to examine the plates; then slight 
differences in brightness can be easily seen. j 
Orion was a good subject for the finding of such 
diffused nebulee. Besides the well-known nebulz around 
¢ and @ Orionis, and besides the many small nebulz, there 
are feeble and widespread nebulosities, some of which 
have been discovered by Profs. W- 
Pickering, Barnard, and the 
writer, with the aid of portrait 
lenses. These would still be 
unknown but for the portrait 
lens, because a plate taken with 
a reflector would cover only a 
minute part of the nebulosities, 
and there would be no parts 
free from nebulosity in this small 
field, to be compared with the 
nebulous parts. 
I may here remark that I dis- 
covered easily the interesting 
connection between the nebulz 
of @ Orion and ¢ Orion (Fig. 1). 
This seems a most important 
example of the connection of two 
large and far distant nebule ; 
and because the connection is 
effected over a wide field, it 
promises to bring new light on 
the knowledge of the situation 
of the nebule in the universe. 
Fig. 1 is a slightly enlarged 
print of a plate of this part of 
the sky, taken with a 6-inch 
Voigtlander lens of 30-inch focus. 
The broad long-spread train ot 
nebulosity, which appears in this 
marvellous bay running from 
¢ Orionis nearly in a straight line 
against S.S.E., becomes broader 
and broader growing southwards, 
and at the same time fainter and 
fainter. It makes a wide curve, 
and runs much more south than 
the brighter parts of the @ Orion 
nebula. Now, in every direction 
we see streams of nebulosity run- 
ning from north, east, and south 
from the (nebula to the @ nebula. 
Especially from the north come 
down many lacerated and finely- 
drawn ribbons of nebulosity con- 
necting the ¢ Orion nebula with 
the @ nebula. The most mar- 
vellous connection is by the 
above-named broad stream, 
which runs much more south 
than the @ nebula, and passes 
over to it from south-east in a 
large arch. 
the and 
hide j 
nebulosity less clear than a slightly larger portrait lens 
would do. 
If the plates are not exposed long enough, various 
devices have to be employed to discover the faint nebu- 
rifts, consequently make the trains of 
losities on the plate. One simple way of doing this, is to 
press the plate ina printing-frame upon smooth white 
paper, and to examine it in the sunlight. In&this way I | 
NO. 1434, VOL. 55] 
Besides these nebule lie very 
extended relatively bright nebu- 
losities to the west of the @ Orion 
nebula, connected with it by 
many streams ; and also mighty nebulosities are situated 
to the east of the circular train, which comes down from 
¢ Orion nebula. These are likewise connected together 
at almost every possible place. 
The picture is a beautiful and marvellous one, yet we 
see only the roughest connections and streams. 
It needs long-sustained efforts and much work before 
we shall be able to know this region, so that we can 
