baskets of provision, evidently going to gipsy in
the fields close by."

THE CASTLE, PARSONSTOWN,
_1848, Aug. 29_.

After tea it was voted that the night was likely to be fine, so we all
turned out. The night was uncertain: sometimes entirely clouded,
sometimes partially, but objects were pretty well seen when the sky
was clear: the latter part was much steadier. From the interruption by
clouds, the slowness of finding with and managing a large instrument
(especially as their finding apparatus is not perfectly arranged) and
the desire of looking well at an object when we had got it, we did not
look at many objects. The principal were, Saturn and the Annular
Nebula of Lyra with the 3-feet; Saturn, a remarkable cluster of stars,
and a remarkable planetary nebula, with the 6-feet. With the large
telescope, the evidence of the quantity of light is prodigious. And
the light of an object is seen in the field without any colour or any
spreading of stray light: and it is easy to see that the vision with a
reflecting telescope may be much more perfect than with a
refractor. With these large apertures, the rings round the stars are
insensible. The planetary nebula looked a mass of living and intensely
brilliant light: this is an object which I do not suppose can be seen
at all in our ordinary telescopes. The definition of the stars near
the zenith is extremely good: with a high power (as 800) they are
points or very nearly so--indeed I believe quite so--so that it is
clear that the whole light from the great 6-feet mirror is collected
into a space not bigger than the point of a needle. But in other
positions of the telescope the definition is not good: and we must
look to-day to see what is the cause of this fault. It is not a fault
in the telescope, properly so-called, but it is either a tilt of the
mirror, or an edge-pressure upon the mirror when the telescope points
lower down which distorts its figure, or something of that kind. So I
could not see Saturn at all well, for which I was sorry, as I could so
well have compared his appearance with what I have seen before. I
shall be very much pleased if we can make out what is the fault of
adjustment, and so correct it as to get good images everywhere. It is
evident that the figuring of the mirror, the polishing, and the
general arrangement, are perfectly managed.