[1] The divan in this sense has been known in Europe certainly since
about the middle of the 18th century. It was fashionable, roughly
speaking, from 1820 to 1850, wherever the romantic movement in
literature penetrated. All the boudoirs of that generation were
garnished with divans; they even spread to coffee-houses, which were
sometimes known as "divans" or "Turkish divans"; and a "cigar divan"
remains a familiar expression.
DIVER, a name that when applied to a bird is commonly used in a sense
even more vague than that of loom, several of the sea ducks or
_Fuligulinae_ and mergansers being frequently so called, to say nothing
of certain of the auks or _Alcidae_ and grebes; but in English
ornithological works the term diver is generally restricted to the
Family known as _Colymbidae_, a very well-marked group of aquatic birds,
possessing great, though not exceptional, powers of submergence, and
consisting of a single genus _Colymbus_ which is composed of three, or
at most four, species, all confined to the northern hemisphere. This
Family belongs to the _Cecomorphae_ of T. H. Huxley, and is usually
supposed to occupy a place between the _Alcidae_ and _Podicipedidae_;
but to which of these groups it is most closely related is undecided.
Professor Brandt in 1837 (_Beitr. Naturgesch. Vogel_, pp. 124-132)
pointed out the osteological differences of the grebes and the divers,
urging the affinity of the latter to the auks; while, thirty years
later, Professor Alph. Milne-Edwards (_Ois. foss. France_, i. pp.
279-283) inclined to the opposite view, chiefly relying on the
similarity of a peculiar formation of the tibia in the grebes and
divers,[1] which indeed is very remarkable, and, in the latter group,
attracted the attention of Willughby more than 230 years ago. On the
other hand Professor Brandt, and Rudolph Wagner shortly after (Naumann's
_Vogel Deutschlands_, ix. p. 683, xii. p. 395), had already shown that
the structure of the knee-joint in the grebes and divers differs in that
the former have a distinct and singularly formed _patella_ (which is
undeveloped in the latter) in addition to the prolonged, pyramidally
formed, procnemial process--which last may, from its exaggeration, be
regarded as a character almost peculiar to these two groups.[2] The
evidence furnished by oology and the newly-hatched young seems to favour
Brandt's views. The abortion of the _rectrices_ in the gerbes, while
these feathers are fairly developed in the divers, is another point that
helps to separate the two Families.
The commonest species of _Colymbus_ is _C. septentrionalis_, known as
the red-throated diver from an elongated patch of dark bay which
distinguishes the throat of the adult in summer dress. Immature birds
want the bay patch, and have the back so much more spotted that they are
commonly known as "speckled divers." Next in size is the black-throated
diver, _C. arcticus_, having a light grey head and a gular patch of
purplish-black, above which is a semicollar of white striped vertically
with black. Still bigger is the great northern diver, _C. glacialis_ or
_torquatus_, with a glossy black head and neck, two semicollars of white
and black vertical stripes, and nearly the whole of the black back and
upper surface of the wings beautifully marked with white spots, varying
in size and arranged in belts.[3] Closely resembling this bird, so as to
be most easily distinguished from it by its yellow bill, is _C. adamsi_.
The divers live chiefly on fish, and are of eminently marine habit,
though invariably resorting for the purpose of breeding to freshwater
lakes, where they lay two dark brown eggs on the very brink; but they
are not unfrequently found far from the sea, being either driven inland
by stress of weather, or exhausted in their migrations. Like most birds
of their build, they chiefly trust to swimming, whether submerged or on
the surface, as a means of progress, but once on the wing their flight
is strong and they can mount to a great height. In winter their range is
too extensive and varied to be here defined, though it is believed never
to pass, and in few directions to approach, the northern tropic; but the
geographical distribution of the several forms in summer requires
mention. While _C. septentrionalis_ inhabits the north temperate zone of
both hemispheres, _C. arcticus_ breeds in suitable places from the
Hebrides to Scandinavia, and across the Russian empire, it would seem,
to Japan, reappearing in the north-west of North America,[4] though its
eastern limit on that continent cannot be definitely laid down; but it
is not found in Greenland, Iceland, Shetland or Orkney. _C. glacialis_,
on the contrary, breeds throughout the north-eastern part of Canada, in
Greenland and in Iceland. It has been said to do so in Scotland as well
as in Norway, but the assertion seems to lack positive proof, and it may
be doubted whether, with the exception of Iceland, it is indigenous to
the Old World,[5] since the form observed in North-eastern Asia is
evidently that which has been called _C. adamsi_, and is also found in
North-western America; but it may be remarked that one example of this
form has been taken in England (_Proc. Zool. Society_, 1859, p. 206) and
at least one in Norway (_Nyt Mag. for Naturvidenskaberne_, 1877, p.
134). (A. N.)