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OCCULTATION—OCEAN AND OCEANOGRAPHY
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his moralized tales of “Jereslaus' Wife” and of “Jonathas,” both from the Gesta Romanorum, which, with his “Learn to die,” belong to his old age. After finally retiring from his privy seal clerkship, he was granted in 1424 sustenance for life in the priory of Southwick, Hants, on which, with his former annuity, he appears to have lived till about the middle of the century. A “Balade to my gracious Lord of Yorke” probably dates from 1448 or later.

The main interest for us in Occleve's poems is that they are characteristic of his time. His hymns to the Virgin, balades to patrons, complaints to the king and the king's treasurer, versified homilies and moral tales, with warnings to heretics like Oldcastle, are illustrative of the blight that had fallen upon poetry on the death of Chaucer. The nearest approach to the realistic touch of his master is to be found in Occleve's “Male Regle.” But these pictures of 15th-century London are without even the occasional flash of humour that lightens up Lydgate's London Lackpenny. Yet Occleve has at least the negative virtue of knowing the limits of his powers. He says simply what he means, and does not affect what he does not feel. A Londoner, to whom the country was evidently a bore, he has not afflicted us with artificial May mornings; and it is doubtful whether a single reference to nature can be found among his poems. He has yet another distinction among his contemporaries: he wrote no allegory. Whether we ascribe it to his lack of “engine,” or to the influence of Chaucer when in his later years he had discovered the limitations of this poetic form, we cannot but be grateful to the poet who has spared us. As a metrist Occleve is also modest of his powers. He confesses that

Fader Chaucer fayn wolde han me taught,
But I was dul and learned lite or naught;

and it is true that the scansion of his verses seems occasionally to require, in French fashion, an accent on an unstressed syllable. Yet his seven-line (or rime royale) and eight-line stanzas, to which he limited himself, are perhaps more frequently reminiscent of Chaucer's rhythm than are those of Lydgate.

A poem, “Ad beatam Virginem,” generally known as the “Mother of God,” and once attributed to Chaucer, is copied among Occleve's works in MS. Phillipps 8151 (Cheltenham), and may thus be regarded as his work. Occleve found an admirer in the 17th century in William Browne, who included his “Jonathas” in the Shepheards Pipe (1614). Browne added a eulogy of the old poet, whose works he intended to publish in their entirety (Works, ed. W. C. Hazlitt, 1869, ii. 196-198). In 1796 George Mason printed six Poems by Thomas Hoccleve never before printed . . .; “De Regimene Principum” was printed for the Roxburghe Club in 1860, and by the Early English Text Society in 1897. See Dr F. J. Furnivall's introduction to Hoccleve's Works; I. The Minor Poems, in the Phillipps MS. 8151, and the Durham MS. III. 9 (Early English Text Society, 1892).  (W. S. M.) 

OCCULTATION (from Lat. occultare, the frequentative of occulere, to hide), in astronomy, the hiding of one celestial body by another passing in front of it; commonly the passage of the moon or of a planet between the observer and a star or another planet.

OCEAN AND OCEANOGRAPHY. “Ocean” is the name applied to the great connected sheet of water which covers the greater part of the surface of the Earth. It is convenient to divide the subject-matter of physical geography into the atmosphere, hydrosphere and lithosphere, and in this sense the ocean is less than the hydrosphere in so far as the latter term includes also the water lying on or flowing over the surface of the land. The conception of an encompassing ocean bounding the habitable world is found in the creation myths of the most ancient civilizations. The Babylonians looked on the world as a vast round mountain rising from the midst of a universal sheet of water. In the Hebrew scriptures the waters were gathered together in one place at the word of God, and the dry land appeared. The Ionian geographers looked on the circular disk of the habitable world as surrounded by a mighty stream named Oceanus, the name of the primeval god, father of gods and men, and thus the bond of union between heaven and earth. The Greek word ὠκεανός is related to the Sanskrit açāyanas, “the encompassing.” Philologists do not know of any related word in Semitic languages. Pictet, however, recognizes allied forms in Celtic languages, e.g. the Irish aigean and Cymric eigiawn.

Since the Pythagorean school of philosophy upheld the spherical as against the disk-shaped world, some of the ancient geographers, including Eratosthenes and Strabo, looked upon the hydrosphere as forming two belts at right angles to each other, one belt of ocean following the equator, the other surrounding the earth from pole to pole as in the terra quadrifida of Macrobius; while others, including Aristotle and Ptolemy, looked upon the inhabited land, or oikumene, as occupying the greater part of the earth's surface, so that the Indian Ocean was an enclosed sea and India (i.e. eastern Asia) was only separated from Europe by the Atlantic Ocean. The latter view prevailed and was as a rule held by the Arab geographers of the middle ages, so that until the discovery of America and of the Pacific Ocean the belief was general that the land surface was greater than the water surface, or that at least the two were equal, as Mercator and Varenius held. Thus it was that a great South Land appeared on the maps, the belief in the prodigious extension of which certainly received a severe shock by Abel Tasman's voyage of circumnavigation, but was only overthrown after Cook's great voyages had proved that any southern land which existed could not extend appreciably beyond the polar circle. Only in our own day has the existence of the southern continent been demonstrated within the modest limits of Antarctica.

Oceanography is the science which deals with the ocean, and since the ocean forms a large part of the earth's surface oceanography is a large department of geography. The science is termed talassografia by the Italians, and attempts have been made without success to introduce the name “thalassography.” Of recent years the use of “hydrography” as the equivalent of physical oceanography has acquired a certain currency, but as the word is also used with more than one other meaning (see Surveying) it ought not to be used for oceanography.

Like geography, oceanography may be viewed in two different ways, and is conveniently divided into general oceanography, which deals with phenomena common to the whole ocean, and special oceanography, which has to do with the individual characteristics of the various divisions of the ocean. This article is restricted to general oceanography in its physical aspects, the closely-related meteorological, biological and economic aspects being dealt with elsewhere.

Methods of Research.—When research in oceanography began, the conditions of the sea were of necessity observed only from the coast and from islands, the information derived from mariners as to the condition of parts of the sea far from land being for the most part mere anecdotes bearing on the marvellous or the frightful. In recent times, especially since the rapid increase in the study of the exact sciences during the 19th century, observations at sea with accurate instruments have become common, and the ships' logs of to-day are provided with headings for entering daily observations of the phenomena of the sea surface. The contents of the sailors' scientific logs were brought together by the American enthusiast in the study of the sea, Matthew Fontaine Maury (1806-1873), whose methods and plans were discussed and adopted at international congresses held in Brussels in 1853 and in London in 1873. By 1904 more than 6800 of these meteorological logs with 7,000,000 observations had been accumulated by the Meteorological Office in London; 20,000 with 10,600,000 observations by the German Marine Observatory at Hamburg; 4700 with 3,300,000 observations by the Central Institute of the Netherlands at de Bilt near Utrecht. The Hydrographic Office of the United States had collected 3800 meteorological logs with 3,200,000 entries before 1888; but since that time the logs have contained only one observation daily (at Greenwich noon) and of these 2,380,000 entries had been received by 1904. In the archives of the French Marine in Paris there were 3300 complete logs with 830,000 entries and 11,000 abstract logs from men-of-war. The contents of these logs, it is true, refer more to maritime meteorology than to oceanography properly so-called, as their main purpose is to