r of these doublets, for he found that they were slowly
revolving round each other. There are a certain number of merely optical
or accidental doublets, but the majority of them are real pairs of suns
revolving round each other.

This relative method of mapping micrometrically a field of neighbouring
stars, and comparing their configuration now and six months hence, was,
however, the method ultimately destined to succeed; and it is, I
believe, the only method which has succeeded down to the present day.
Certainly it is the method regularly employed, at Dunsink, at the Cape
of Good Hope, and everywhere else where stellar parallax is part of the
work.

Between 1830 and 1840 the question was ripe for settlement, and, as
frequently happens with a long-matured difficulty, it gave way in three
places at once. Bessel, Henderson, and Struve almost simultaneously
announced a stellar parallax which could reasonably be accepted. Bessel
was a little the earliest, and by far the most accurate. His, indeed,
was the result which commanded confidence, and to him the palm must be
awarded.

He was largely a self-taught student, having begun life in a
counting-house, and having abandoned business for astronomy. But
notwithstanding these disadvantages, he became a highly competent
mathematician as well as a skilful practical astronomer. He was
appointed to superintend the construction of Germany's first great
astronomical observatory, that of Koenigsberg, which, by his system,
zeal, and genius, he rapidly made a place of the first importance.

Struve at Dorpat, Bessel at Koenigsberg, and Henderson at the Cape of
Good Hope--all of them at newly-equipped observatories--were severally
engaged at the same problem.

But the Russian and German observers had the advantage of the work of
one of the most brilliant opticians--I suppose the most brilliant--that
has yet appeared: Fraunhofer, of Munich. An orphan lad, apprenticed to a
maker of looking-glasses, and subject to hard struggles and privations
in early life, he struggled upwards, and ultimately became head of the
optical department of a Munich firm of telescope-makers. Here he
constructed the famous "Dorpat refractor" for Struve, which is still at
work; and designed the "Koenigsberg heliometer" for Bessel. He also made
a long and most skilful research into the solar spectrum, which has
immortalized his name. But his health was broken by early trials, and he
died at the age of thirty-ni