ully,
H.W. HERSCHEL.

TO WILLIAM SOMERVILLE, ESQ.

* * * * *

Spectrum analysis has shown that there is a vast quantity of
self-luminous gaseous matter in space, incapable of being reduced into
stars, however powerful the telescope through which it is observed.
Hence the old opinion once more prevails, that this is the matter of
which the sun and stellar systems have been formed, and that other
stellar systems are being formed by slow, continuous condensation. The
principal constituents of this matter are, the terrestrial gases,
hydrogen, and nitrogen. The yellow stars, like the sun, contain
terrestrial matter. The nebulous and stellar constituents were chiefly
discovered by Dr. Huggins.

Somerville and I were always made welcome by Sir James South, and at
Campden Hill I learnt the method of observing, and sometimes made
observations myself on the double stars and binary systems, which,
worthless as they were, enabled me to describe better what others had
done. One forenoon Somerville and I went to pay a visit to Lady South.
Sir James, who was present, said, "Come to the observatory, and measure
the distance of Mercury from the sun; for they are in close
approximation, and I wish to see what kind of observation you will
make." It was erroneous, as might have been expected; but when I took
the mean of several observations, it differed but little from that which
Sir James South had made; and here I learnt practically the importance
of taking the mean of approximate quantities.

* * * * *

Dr. Wollaston, Dr. Young, and the Katers died before I became an author;
Lord Brougham was one of the last of my scientific contemporaries, all
the rest were younger than myself, and with this younger set, as with
their predecessors, we had most agreeable and constant intercourse.
Although we lived so much in scientific society we had all along been on
the most friendly and intimate terms with the literary society of the
day, such as Hallam, Milman, Moore, Malthus, &c., &c. The highly
intellectual conversation of these was enlivened by the brilliant wit of
my early friend, Sydney Smith, who was loved and admired by every one.
His daughter married our friend Sir Henry Holland, the distinguished
physician, well known for his eminent literary and scientific
acquirements as well as for his refined taste.

No house in London was mo