pected
to find they had crossed each other at this apparition, but to my
surprise I find they have become a fair round disc, which my highest
powers will not elongate--in fact, _a single star_! I shall watch
with no little interest for the reappearance of the second [Greek: g].

My dear madam,
Your truly obliged servant,
W.H. SMYTH.

* * * * *

This eclipse was also seen by Sir John Herschel at the Cape of Good
Hope, as well as by many astronomers in Europe provided with instruments
of great optical power. In 1782 Sir William Herschel saw one of the
stars of Zeta Herculis eclipse the other.

In the "Connexion of the Physical Sciences" I have given an abridged
account of Sir John Herschel's most remarkable discoveries in the
southern hemisphere; but I may mention here that he determined the
position and made accurate drawings of all the nebulae that were
distinctly visible in his 20 ft. telescope. The work he published will
be a standard for ascertaining the changes that may take place in these
mysterious objects for ages to come. Sir William Herschel had determined
the places of 2,500 nebulae in the northern hemisphere; they were
examined by his son, and drawings made of some of the most remarkable,
but when these nebulae were viewed through Lord Rosse's telescope, they
presented a very different appearance, showing that the apparent form of
the nebulae depends upon the space-penetrating power of the telescope, a
circumstance of vital importance in observing the changes which time may
produce on these wonderful objects.

[Long afterwards Lord Rosse wrote in reply to some questions which
my mother had addressed to him on this subject:--]

FROM THE EARL OF ROSSE TO MRS. SOMERVILLE.

CASTLE, PARSONSTOWN, _June 12th, 1844_.

DEAR MRS. SOMERVILLE,

I have very reluctantly postponed so long replying to your
inquiries respecting the telescope, but there were some points upon
which I was anxious to be enabled to speak more precisely. The
instrument we are now using is 3 feet aperture, and 27 feet focus,
and in the greater proportion of the nebulae which have been observed
with it some new details have been brought out. Perhaps the most
interesting general result is that, as far as we have gone,