VISUAL SENSATION. 186 VITAL STATISTICS. discovered until nearly middle age that he was himself a dichromate. Consult: Elibinghaus, Grimdzuge d-cr Psycholo- gic (Leipzig, 18!)7) ; Konig, Gesammcltc Ahhand- lungai -III- physiologisclicn Oijlik (ib., liW'^l; Calkins, IntroducUoit to Psychology (Xew ork, 1901); Baldwin. Dictionary of Philosophy and Psychology (New York and Loudon, 1902). VISVAMITBA, vish-vii'mit-ra. A celebrated priest and sage of ancient India. He belonged orig- inally to the Kshatrya or warrior caste, being King of Kanauj (q.v.), but by,extraordinary acts of religious austerity he e.xalted himself to the dignity of the priestly class, an example without parallel in ancient India. In the Pig-Veda, espe- cially in the third book, a number of hymns are ascribed to him as author, and his bitter rivalry with the sage Vasishtha (q.v.) for the position of chief priest at the court of King Sudas, to- gether with his competitor's greater success, form incidents that are reflected on an historic back- ground. The traditional rivalry between the two Appears likewise in the epic and in the Puraiias (q.v.). The first book of the Ildmayana (q.v.) gives a legendary account of the way in which Visvamitra rose. An incident of Visvamitra's life during this period forms the subject of Kshemis- vara's Canda-Ktuisika, or 'Wrath of the Descend- ant of Kusika,' which is one of the best of the Sanskrit dramas. Consult: Muir, Original San- skrit Texts, vol. i. (2d ed., London, 1SG8) ; Kaegi-Arrowsmith, The Rigveda (Boston, I88I1) ; Wilkins, Hindu Mythology (2d ed., London, 1900). See Haeischaxde.. VIS-VIVA. A term devised by Leibnitz (1095) and formerly used to denote the product of the mass of a body into the square of its velocity. It was applied to one-half this quan- tity, or i/2mi;', by Coriolis. This is now known ask'inetie'energy. See ExEBGETlcs. VITACE.ffi (Neo-Lat. nom. pi., from Lat. vitis, vine, from viere, to twine, twist ; ultimately connected with Eng. u-ithy), or The Vine Fam- ily; also called Ai[PELID.ce.s;. A natural order of dicotyledonous plants, of which the grape may be rcga'rded as the type. About 450 species are known, natives of warm and temperate cli- mates, all shrubs, mostly climbing. The only genus of the order of much economic value is Vitis, the grape, but species of the genus Cissus and of Ampelopsis (which many unite with Vitis) are widely planted for ornament. VITA'LIA'NUS. Tope 657-672. He was bom in Campania and came to the Papal throne when the fireck Emperor Constans 11. (d. 668) was persecuting those who opposed monothe- litism. Tactfully ho ignored this ojiposition and cultivated friendly relations with the Emperor, with such success that the latter made him a visit at Komo in G63. He also juit Constans's suc- cessor C'onstantine IV. under obligation to the Papal See l)y helping him in his campaign against a rival. This Pope is also reinembercd as the Bender of the distinguishecl Thecidoro (see TiiE- ODORK oi- Ta1!SUS) lo the See of C;mterbiry. VITALIS, vf-tii'lis. The nom-de-jdume of Sjijberg. the Swedish pnet. VITA'LIS OKDER'ICUS ( lO-S-cllW) . A Norman historian. He was the son of Odelerius, confessor to Roger of Montgomery, and was born at Atcham, near Shrewsbury, England. He enteretl the Jlonastery of Saint Evroult in Nor- mandy in 1085, and with the exception of short intervals spent' the remainder of his life there. At the suggestion of Rober du Sap and Gufrin des Essarts he began to compose the annals of Saint Evroult, and afterwards expanded his work into a general history of thirteen books, bearing the title Historiu Ecclesiastica. The work, which begins with the Apostolic era, is of value cUietty for the period in which Ordericus himself lived. The orisiinal manuscript is now in the Biblio- thfeque Rationale at Paris. It was first pub- lished in Duchesne's Historice Sormanorum Hcriptores in 1619. It is contained in iligne's Patrologia Latina, and an English translation of it was published in four volumes in Bolm's Antiquarian Library (1853-55). ■TTAL STATISTICS (Lat. vitalis, relating to life, from cita, life, from vivere, to live). That branch of statistics which studies the growth and changes of population. The facts which it seeks to interpret are derived from two main sources, censuses and registration reports. Censuses give information regarding population at a certain day, and sliow the changes and growth of population only by com- parison between the results of two or more censuses. Registration reports are obtained by tabulating the records of certain important events made at or near the time of their occur- rence. The scope and accuracy of these registra- tion reports vary greatly with time and place. They usually include deaths, marriages, and births, and sometimes divorces, with various sta- tistical facts about each. The number of such occurrences is controlled mainly by the number of people in the community for which the report speaks. To exclude tins, the most im- portant cause of dillerence in the figures, it is usual to compute the average number of births, deaths, or marriages occurring in a fixed unit of time, usually a calendar year, and in a fixed unit of population, usually 1000. The result of such a computation has been named a rate. The death rate means the average number of persons dying in a year to each 1000 of the population. The Tnarriage rate and the birth rate have simi- lar meanings, except that the first term of the ratio is the number of persons marrying or the numl>er of children born, respectively. Rates of this class are sometimes known as crude or simple rates in distinction from refined or ciu-reeted rates in which the unit of population may be a o-roup eaeli of whom possesses certain sjiecified characteristics. Thus death rates are computed for a specified age and sex and occupation and race, botli terms of the ratio being corresjiond- ingly limited, as for example the death rate of negro married women between twenty-five and thfrty-four years of age. Tlio main statistical facts regarding the popu^ lation being found under the heading Statistics, the present article is confined to the statistical results derived from rates. ({EXERAi, Death Rate. Perhaps the highest deatli rate for great countries where records are kept occurs in Russia, with 33.5 per 1000 on the average for 1884-93; Chile, with 33.3: and Hungary, with 32.4. The lowest death rates are found ill Great Britain, tlu- Scandinavian coun-
