Optics, is the same with the divergency of the rays of light.

Point of Dispersion is the point from which refracted rays begin to diverge, where their refraction renders them divergent.

Dispersion of Mankind, in the history of the world, was occasioned by the confusion of tongues, and took place in consequence of the overthrow of Babel at the birth of Peleg (whence he derived his name); and by the account given of his ancestors (Gen. chap. xi. 10-16) this appears to have happened in the 101st year after the Flood, according to the Hebrew chronology, and by the Samaritan computation in the 401st. However, various difficulties have been suggested by chronologists concerning the true era of this event. Sir John Marsham and others, in order to reconcile the Hebrew and Egyptian chronologies, maintain a dispersion of mankind before the birth of Peleg; whilst others, unable to find numbers sufficient for the plantation of colonies in the space of 101 years, according to the Hebrew computation, fix the dispersion towards the end of Peleg's life, thus following the computation of the Jews. Petavius assigns the 153d year after the Flood; Cumberland the 180th; and Usher, though he generally refers it to the time of Peleg's birth, in one place assigns the 131st after the Flood for this event. Mr Shuckford supposes the dispersion to have been gradual, and to have commenced with the separation of some companies at the birth of Peleg, and to have been completed thirty-one years afterwards. According to the calculation of Petavius, the number of inhabitants on the earth at the birth of Peleg amounted to 32,768; but Cumberland makes them 30,000; Mr Mede states them at only 7000 men, besides women and children; and Mr Whiston, who supposes that mankind now double themselves in about 400 years, and that they doubled themselves between the deluge and the time of David in sixty years at a medium, when their lives were six or seven times as long as they have been since, by his computation produces about 2389; a number much too inconsiderable for the purposes of separating and forming distinct nations. This difficulty induced Mr Whiston to dispense reject the Hebrew and adopt the Samaritan chronology, as many others have done; which, by allowing an interval of 401 years between the Flood and the birth of Peleg, furnishes, by the last-mentioned mode of computation, more than 240,000 persons.

As to the manner of the dispersion of the posterity of Noah from the plain of Shinar, it was undoubtedly conducted with the utmost regularity and order. The sacred historian informs us that they were divided in their lands, every one according to his tongue, according to his family, and according to his nation (Gen. x. 5, 20, 31); and thus, as Mr Mede observes, they were ranged according to their nations, and every nation was ranged by its families, so that each nation had a separate lot, and each family a separate share in what fell to every nation. The following abstract will serve to give a general idea of their respective settlements. Japhet, Noah's eldest son, had seven sons. Of these, Gomer was he whose descendants inhabited those parts of Asia which lie upon the Ægean Sea and Hellespont northward, containing Phrygia, Pontus, Bithynia, and a great part of Galatia. The Galatians, according to Josephus, were called Gomeræi; while the Cimmeri, according to Herodotus, occupied this track of country; and from these Gomerians, Cimmeri, or Celtæ, Mr Camden derives our ancient Britons, who still retain the name Cymer or Cymeri. Magog, the second son of Japhet, was probably the father of the Scythians on the east and north-east of the Euxine Sea. Madai planted Media, though Mr Mede assigns Macedonia to his share. Javan was the father of the Græcians about Ionia, whose country lies along the coast of the Mediterranean Sea; the radices of Javan and Ionian being the same. To Tubal and Meshoch belonged Cappadocia and the country which lies on the borders of the Euxine Sea; and from them, migrating over Caucasus, it is supposed the Russians and Muscovites are descended. Tiras occupied Thrace. The sons of Shem were five: Elam, whose country lay between the Medes and Mesopotamians, and was called by the Gentile writers Elamæi (Josephus calls the Elamites the founders of the Persians); Ashur, who was driven out of Shinar by Nimrod, afterwards settled in Assyria, and there built Nineveh and other cities; Arphaxad, who gave name to the country which Ptolemy calls Arraphætia, a province of Assyria, though Josephus makes him the father of the Chaldees; Lud, who inhabited and gave name to the country of Lydia, about the river Maeander, remarkable for its windings, in Asia Minor; and Aram, the father of the Syrians. Ham, the youngest son of Noah, had four sons: Cush, whose posterity spread into the several parts of Arabia over the borders of the land of Edom, into Arabia Felix, up to Midian and Egypt; Mizraim, the father of them who inhabited Egypt and other parts of Africa; Phut, to whom Bochart assigns the remaining part of Africa, from the Lake of Tritonides to the Atlantic Ocean, called Libyæ; and Canaan, to whom belonged the land of Canaan, whence the Phœnicians derived their origin.

Dr Bryant has advanced a new hypothesis on this subject, and supported it with his usual acuteness and learning. He maintains that the dispersion as well as the confusion of tongues was local, and limited to the inhabitants of the province of Babel; that the separation and distribution recorded to have taken place in the days of Peleg (Gen. x. 25, 31, 32), which was the result of divine appointment, occasioned a general migration; and that all the families amongst the sons of men were concerned in it. The house of Shem, from which the Messiah was to spring, was particularly regarded in this distribution. The portion of his children was near the place of separation; they