ivisible only into individual persons or things. (See further
DIVISION.) In astronomy the term is used for the aspect of the moon or
of a planet when apparently half illuminated, so that its disk has the
form of a semicircle.

DICK, ROBERT (1811-1866), Scottish geologist and botanist, was born at
Tullibody, in Clackmannanshire, in January 1811. His father was an
officer of excise. At the age of thirteen, after receiving a good
elementary education at the parish school, Robert Dick was apprenticed
to a baker, and served for three years. In these early days he became
interested in wild flowers--he made a collection of plants and gradually
acquired some knowledge of their names from an old encyclopaedia. When
his time was out he left Tullibody and gained employment as a journeyman
baker at Leith, Glasgow and Greenock. Meanwhile his father, who in 1826
had been removed to Thurso, as supervisor of excise, advised his son to
set up a baker's shop in that town. Thither Robert Dick went in 1830, he
started in business as a baker and worked laboriously until he died on
the 24th of December 1866. Throughout this period he zealously devoted
himself to studying and collecting the plants, mollusca and insects of a
wide area of Caithness, and his attention was directed soon after he
settled in Thurso to the rocks and fossils. In 1835 he first found
remains of fossil fishes; but it was not till some years later that his
interest became greatly stirred. Then he obtained a copy of Hugh
Miller's _Old Red Sandstone_ (published in 1841), and he began
systematically to collect with hammer and chisel the fossils from the
Caithness flags. In 1845 he found remains of _Holoptychius_ and
forwarded specimens to Hugh Miller, and he continued to send the best of
his fossil fishes to that geologist, and to others after the death of
Miller. In this way he largely contributed to the progress of geological
knowledge, although he himself published nothing and was ever averse
from publicity. His herbarium, which consisted of about 200 folios of
mosses, ferns and flowering plants "almost unique in its completeness,"
is now stored, with many of his fossils, in the museum at Thurso. Dick
had a hard struggle for existence, especially through competition during
his late years, when he was reduced almost to beggary: but of this few,
if any, of his friends were aware until it was too late. A monument
erected in the new cemetery at Thurso testifies to the r