ures on the Reunion of the Churches_; _The Vatican Decrees;
Studies in European History_ (tr. M. Warre, 1890); _Miscellaneous
Addresses_ (tr. M. Warre, 1894).

See _Life_ by J. Friedrich (3 vols. 1899-1901); obituary notice in
_The Times_, 11th January 1890; L. von Kobell, _Conversations of Dr
Dollinger_ (tr. by K. Gould, 1892). (J. J. L.*)

DOLLOND, JOHN (1706-1761), English optician, was the son of a Huguenot
refugee, a silk-weaver at Spitalfields, London, where he was born on the
10th of June 1706. He followed his father's trade, but found time to
acquire a knowledge of Latin, Greek, mathematics, physics, anatomy and
other subjects. In 1752 he abandoned silk-weaving and joined his eldest
son, Peter Dollond (1730-1820), who in 1750 had started in business as a
maker of optical instruments. His reputation grew rapidly, and in 1761
he was appointed optician to the king. In 1758 he published an "Account
of some experiments concerning the different refrangibility of light"
(_Phil. Trans._, 1758), describing the experiments that led him to the
achievement with which his name is specially associated, the discovery
of a means of constructing achromatic lenses by the combination of crown
and flint glasses. Leonhard Euler in 1747 had suggested that achromatism
might be obtained by the combination of glass and water lenses. Relying
on statements made by Sir Isaac Newton, Dollond disputed this
possibility (_Phil. Trans._, 1753), but subsequently, after the Swedish
physicist, Samuel Klingenstjerna (1698-1765), had pointed out that
Newton's law of dispersion did not harmonize with certain observed
facts, he began experiments to settle the question. Early in 1757 he
succeeded in producing refraction without colour by the aid of glass and
water lenses, and a few months later he made a successful attempt to get
the same result by a combination of glasses of different qualities (see
TELESCOPE). For this achievement the Royal Society awarded him the
Copley medal in 1758, and three years later elected him one of its
fellows. Dollond also published two papers on apparatus for measuring
small angles (_Phil. Trans._, 1753, 1754). He died in London, of
apoplexy, on the 30th of November 1761.

An account of his life, privately printed, was written by the Rev.
John Kelly (1750-1809), the Manx scholar, who married one of his
granddaughters.

DOLMAN (from Turk. _d[=o]l[=a]m[=a]n_), originally a long and loose