[1] Besides these islands there are a few small islands farther N.,
and W. of Antelope, Stansbury Island, which, like Antelope and
Fremont Islands, is connected with the mainland by a bar sometimes
uncovered, and rarely in more than a foot of water.
GREAT SLAVE LAKE (ATHAPUSCOW), a lake of Mackenzie district, Canada. It
is situated between 60 deg. 50' and 62 deg. 55' N. and 108 deg. 40' and
117 deg. W., at an altitude of 391 ft. above the sea. It is 325 m. long,
from 15 to 50 m. wide, and includes an area of 9770 sq. m. The water is
very clear and deep. Its coast line is irregular and deeply indented by
large bays, and its north-eastern shores are rugged and mountainous. The
western shores are well wooded, chiefly with spruce, but the northern
and eastern are dreary and barren. It is navigable from about the 1st of
July to the end of October. The Yellow-knife, Hoarfrost, Lockhart
(discharging the waters of Aylmer, Clinton-Colden and Artillery Lakes),
Tchzudezeth, Du Rocher, Hay (400 m. in length), and Slave rivers empty
into Great Slave Lake. The bulk of its water empties by the Mackenzie
river into the Arctic Ocean, but a small portion finds its way by the
Ark-i-linik river into Hudson's Bay. It was discovered in 1771 by Samuel
Hearne.
GREAT SOUTHERN OCEAN, the name given to the belt of water which extends
almost continuously round the globe between the parallel of 40 deg. S.
and the Antarctic Circle (66-1/2 deg. S.). The fact that the southern
extremity of South America is the only land extending into this belt
gives it special physical importance in relation to tides and currents,
and its position with reference to the Antarctic Ocean and continent
makes it convenient to regard it as a separate ocean from which the
Atlantic, Pacific and Indian Oceans may be said to radiate. (See OCEAN.)
GREAVES, JOHN (1602-1652), English mathematician and antiquary, was the
eldest son of John Greaves, rector of Colemore, near Alresford in
Hampshire. He was educated at Balliol College, Oxford, and in 1630 was
chosen professor of geometry in Gresham College, London. After
travelling in Europe, he visited the East in 1637, where he collected a
considerable number of Arabic, Persian and Greek manuscripts, and made a
more accurate survey of the pyramids of Egypt than any traveller who had
preceded him. On his return to Europe he visited a second time several
parts of Italy, and during his stay at Rome instituted inquiries into
the ancient weights and measures. In 1643 he was appointed to the
Savilian professorship of astronomy at Oxford, but he was deprived of
his Gresham professorship for having neglected its duties. In 1645 he
essayed a reformation of the calendar, but his plan was not adopted. In
1648 he lost both his fellowship and his Savilian chair on account of
his adherence to the royalist party. But his private fortune more than
sufficed for all his wants till his death on the 8th of October 1652.
Besides his papers in the _Philosophical Transactions_, the principal
works of Greaves are _Pyramidographia, or a Description of the
Pyramids in Egypt_ (1646); _A Discourse on the Roman Foot and_
_Denarius_ (1649); and _Elementa linguae Persicae_ (1649). His
miscellaneous works were published in 1737 by Dr Thomas Birch, with a
biographical notice of the author. See also Smith's _Vita quorundam
erudit. virorum_ and Ward's _Gresham Professors_.
GREBE (Fr. _grebe_), the generally accepted name for all the birds of
the family _Podicipedidae_,[1] belonging to the group _Pygopodes_ of
Illiger, members of which inhabit almost all parts of the world. Some
systematic writers have distributed them into several so-called genera,
but, with one exception, these seem to be insufficiently defined, and
here it will be enough to allow but two--Latham's _Podiceps_ and the
_Centropelma_ of Sclater and Salvin. Grebes are at once distinguishable
from all other water-birds by their rudimentary tail and the peculiar
structure of their feet, which are not only placed far behind, but have
the tarsi flattened and elongated toes furnished with broad lobes of
skin and flat blunt nails.
[Illustration: Great Crested Grebe.]
In Europe are five well-marked species of _Podiceps_, the commonest and
smallest of which is the very well-known dab-chick of English ponds, _P.
fluviatilis_ or _minor_, the little grebe of ornithologists, found
throughout the British Islands, and with a wide range in the old world.
Next in size are two species known as the eared and horned grebes, the
former of which, _P. nigricollis_, is a visitor from the south, only
occasionally showing itself in Britain and very rarely breeding, while
the latter, _P. auritus_, has a more northern range, breeding
plentifully in Iceland, and is a not uncommon winter-visitant. Then
there is the larger red-necked grebe, _P. griseigena_, also a northern
bird, and a native of the subarctic parts of both Europe and America,
while lastly the great crested grebe, _P. cristatus_ or gaunt--known as
the loon on the meres and broads of East Anglia and some other parts of
England, is also widely spread over the old world. North America is
credited with seven species of grebes, of which two (_P. griseigena_ and
_P. auritus_) are admitted to be specifically inseparable from those
already named, and two (_P. occidentalis_ and _P. californicus_) appear
to be but local forms; the remaining two (_P. dominicus_ and _P.
ludovicianus_) may, however, be accounted good species, and the last
differs so much from other grebes that many systematists make it the
type of a distinct genus, _Podilymbus_. South America seems to possess
four or five more species, one of which, the _P. micropterus_ of Gould
(_Proc. Zool. Society_, 1858, p. 220), has been deservedly separated
from the genus _Podiceps_ under the name _Centropelma_ by Sclater and
Salvin (_Exot. Ornithology_, p. 189, pl. xcv.), owing to the form of its
bill, and the small size of its wings, which renders it absolutely
flightless. Lake Titicaca in Bolivia is, so far as is known at present,
its only habitat. Grebes in general, though averse from taking wing,
have much greater power of flight than would seem possible on
examination of their alar organs, and are capable of prolonged aerial
journeys. Their plumage is short and close. Above it is commonly of some
shade of brown, but beneath it is usually white, and so glossy as to be
in much request for muffs and the trimming of ladies' dresses. Some
species are remarkable for the crests or tippets, generally of a
golden-chestnut colour, they assume in the breeding season. _P. auritus_
is particularly remarkable in this respect, and when in its full nuptial
attire presents an extraordinary aspect, the head (being surrounded, as
it were, by a _nimbus_ or aureole, such as that with which painters
adorn saintly characters), reflecting the rays of light, glitters with a
glory that passes description. All the species seem to have similar
habits of nidification. Water-weeds are pulled from the bottom of the
pool, and piled on a convenient foundation, often a seminatant growth of
bogbean (_Menyanthes_), till they form a large mass, in the centre of
which a shallow cup is formed, and the eggs, with a chalky white shell
almost equally pointed at each end, are laid--the parent covering them,
whenever she has time to do so, before leaving the nest. Young grebes
are beautiful objects, clothed with black, white and brown down,
disposed in streaks and their bill often brilliantly tinted. When taken
from the nest and placed on dry ground, it is curious to observe the way
in which they progress--using the wings almost as fore-feet, and
suggesting the notion that they must be quadrupeds instead of birds.
(A. N.)