with great simplicity, account for all the 
phenomena of the milky way, which, accord- 
ing to this hypothesis, is no other than the 
appearance of the projection of the stars 
contained in this stratum, and its secondary 
branch. See Galaxy. 
In another paper on the same subject, he 
says, that the milky way is a most extensive 
stratum of stars of various sizes admits no 
longer of the least doubt ; and that our sun 
is actually one of the heavenly l)odies be- 
longing to it is as evident. 
We will now, says the Doctor, retreat to 
our own retired station in one of the planets 
attending a star in the great combination, 
with numberless others ; and in order to in- 
vestigate what will be the appearances from 
this contracted situation let us begin with 
the naked eye. The stars of the first mag- 
nitude, being in all probability the nearest, 
will furnish us with a step to begin our 
scale; setting off, therefore, with the dis- 
tance of Sirius or Arcturus, for instance, as 
unity, we will at present suppose, that those 
of the second magnitude are at double, and 
those of the third at treble the distance, and 
so forth. Taking it, then, for granted, that 
a star of the seventh magnitude is about 
seven times as far from , us as one of the first, 
it follows that an observer, who is enclosed 
in a globular cluster of stars, and not far 
from the centre, will never be able, with 
the naked eye, to see to the end of it : for 
since, according to the above estimations, 
be can only extend his view about seven 
times the distance of Sirius, it cannot be 
expected that his eyes should reach the 
borders of a cluster, which has, perhaps, 
not less than fifty stars in depth every 
where around him. The whole universe, 
therefore, to him, will be comprised in a set 
of constellations, richly ornamented with 
scattered stars of all sizes. Or if the united 
brightness of a neighbouring cluster of stars 
should, in a remarkably clear night, reach 
his sight, it will put on the appearance of a 
small, faint, nebulous cloud, not to be per- 
ceived without the greatest attention. Al- 
lowing him the use of a common telescope 
he begins to suspect that all the milkyness 
of the bright path which surrounds the 
sphere may be owing to stars. By increas- 
ing his power of vision, he becomes certain 
that the milky way is, indeed, no other than 
a collection of very small stars, and the ne- 
bulae nothing but clusters of stars. 
Dr. Herschel then solves a general pro- 
blem for computing the length of the visual 
ray : that of the telescope, which he uses, 
will reach to stars 497" times the distance of 
Sinus. Now, according to the Doctor’s 
reasoning, Sirius cannot be nearer than 
100.000 X 194,000,000 miles, therefore his 
telescope will, at least, reach to 100,000 x 
194,000,000 X 49? miles. And Dr. Her- 
schel says, that in the most crowded part of 
the milky way, he has had fields of view 
that contained no less than 588 stars, and 
these were continued for many minutes, so 
that, in a quarter of an hour, he has seen 
116.000 stars pass through the field view of 
a telescope of only 1.5' aperture : and at 
another time, in 41 minutes, he saw 258,000 
^ars pass through the field of his telescope. 
Every improvement in his telescopes has 
discovered stars not seen before, so that 
there appears no bounds to their number, 
or to the extent of the universe. 
The sun, like many other stars, has pro- 
bably a progressive motion, directed to- 
wards the constellation Hercules. Dr. 
Herschel, on this subject, observes that 
the apparent proper motions of 44 stars out 
of 56 are nearly in the direction which 
would be the result of such a real motion of 
the solar system ; and that the bright stare 
Arcturus and Sirius, which are probably 
the nearest to us, have, as they ought, ac- 
cording to this theory, the greatest apparent 
motions. Again, the star Castor, appears 
when viewed with a telescope, to consist of 
two stars, of nearly equal magnitude ; and 
though they have both an apparent motion 
they have never been found to change 
their distance with respect to one another 
a single second, a circumstance which is ea- 
sily understood if both their apparent mo- 
tions are supposed to arise from the real 
motion of the sun. 
The sun revolves on his axis in 25'' 10 ^ 
with respect to the fixed stars ; this axis is 
directed towards a point about halfway be- 
tween the pole star and Lyra, the plane of 
the rotation being inclined a little more 
than 7“ to that in which the earth revolves. 
The direction of this motion is from west 
to east. All the rotations of the different 
bodies which compose the solar system as 
far as they have been ascertained, are in 
the same direction, and likewise all their 
revolutions, excepting those of some of the 
comets, and those of some of the satellites of 
the Herschel planet. 
The time and the direction of the sun’s 
rotation are ascertained by the change of 
the situation of the spots, which are usually 
visible oil his disc, and which some astro- 
nomers supposed to be elevations, and 
