knowledge. Civilization became impregnable: the ascendant of civilized nations over the other parts of the human species was no longer capable of being shaken; and, from the beginning of this new career of society, it became impossible to arrest its progress, or permanently to enslave the understanding. In the general history of the human mind, the Verulamian reformation of philosophy, may doubtless be regarded as a portion of that great revolution by which the fourth epoch is distinguished. But in the history of science it may, with propriety, be separated from the general movement of society, and considered apart as forming a fifth epoch in the progress of knowledge. Columbus, Luther, and Bacon are, perhaps, in modern times, the men of whom it may be said, with the greatest probability, that, if they had not existed, the whole course of human affairs in after ages would have been varied. So much has been said of the genius of Bacon, and of the reformation which he effected in philosophy, that I should prove it to be vain to attempt any additional observation on that subject. But the most important of Bacon's writings has been illustrated by a commentary, small indeed in extent, but, in my opinion, of inestimable value, as it exhibits a perfect model of the method by which the whole of that great work might be adapted to the present state of science. I allude to Mr. Playfair's observations on those parts of the Novum Organum which relate to the various sorts of prejudice, and the comparative value of facts in physical enquiry, contained in his admirable discourse on the progress of the physical and mathematical sciences. He thus eloquently describes the mind, and genius, and character of that extraordinary man :— "The power and compass of his (Bacon's) mind, which could form such a plan before hand, and trace not merely the outline, but many of the most minute ramifications, of sciences which did not yet exist, must be an object of admiration to all succeeding ages. He is destined, if indeed any thing in the world be so destined, to remain an instantia singularis among men; and, as he has had no rival in the times which are past, so is he likely to have none in the times which are to come. Before any parallel to him can be found, not only must a man of the same talents be produced, but he must be placed in the same circumstances; the memory of his predecessor must be effaced, and the light of science, after being entirely extinguished, must be again beginning to revive. If a second Bacon is ever to arise, he must be ignorant of the first. The range which Bacon's speculations embraced was altogether immense. He cast a penetrating eye on the whole of science, from its feeblest and most infantine state, to that strength and perfection from which it was then so remote, and which it is perhaps destined to approach to continually, but never to attain. More substitutes might be found for Galileo than for Bacon. More than one could be mentioned, who, in the place of the former, would probably have done what he did; but the history of human knowledge points out nobody of whom it can be said, that, placed in the situation of Bacon, he would have done what Bacon did; no man whose prophetic genius would have enabled him to delineate a system of science which had not yet begun to exist!—who could have derived the knowledge of what ought to be from what was not, and who could have become so rich in wisdom, though he received from his predecessors no inheritance but their errors." I am inclined, therefore, to agree with D'Alembert, "that when one considers the sound and enlarged views of this great man, the multitude of the objects to which his mind was turned, and the boldness of his style, which unites the most sublime images with the most rigorous precision, one is disposed to regard him as the greatest, the most universal, and the most eloquent of philosophers. LESSON THE FIRST. DIVISIONS OF TIME. 1. Chronology is the science which relates to time, and treats of the division of it into certain portions, as days, months, years. 2. The principal divisions of time are those marked out by the revolutions of the heavenly bodies, viz. days, lunar months, and years. 3. A day, in common speech, means that period of time during which the sun remains above the horizon : but in a philosophical sense it denotes the time of a complete revolution of the earth about its axis. 4. The beginning of the day is variously reckoned by different nations: some reckon it from sun-rise, and some from sun-set. In most European nations the day is computed from midnight, but modern astronomers count the day from noon. 5. By the Jews and Romans the day and night were divided into four watches: the first commenced at six in the morning; the second at nine; the third at twelve; and the fourth at three in the afternoon. The night was divided in a similar manner. 6. The Greeks divided their time into portions of ten days each; the Chinese into those of fifteen days, and the Mexicans into those of thirteen days. But the Jews, Oriental nations, and other civilized people, have made use of weeks of seven days each. 7. In the Old Testament the term week is sometimes applied to a period of seven years, as well as of seven days. 8. The month was at first suggested by the phases of the moon, and hence months were originally lunar. 9. Months are divided into astronomical and civil: astronomical months are measured by the revolutions of the moon, which are either periodical or synodical. 10. The periodical lunar month is computed by the time which elapses between the departure of the moon from any part of her orbit to her return to the same point, which is 27 days, 7 hours, 43 minutes. 11. The synodical month is reckoned from one conjunction of the sun with the moon to another, and its average length is about 29 days, 12 hours, 44 minutes. 12. The civil month is that space of time by means of which the solar year is divided into twelve parts. 13. The solar year is divided into 12 months of 30 and 31 days, excepting February, which contains 28 days, but every fourth year February contains 29 days. 14. The year is measured by the motion of the earth round the sun, and it formerly consisted of 12 lunar months, supposed to contain 30 days each. 15. By Julius Cæsar the year was ordained to consist of 365 days, 6 hours, which is about 11 minutes too long; the true length of the year is 365 days, 5 hours, H 48 minutes, 48 seconds: upon this the new style is reckoned. 16. The common year contains, therefore, 365 days, but every fourth year, called leap year, consists of 366 days; to avoid the excess which this would occasion, every hundredth year is common, and contains only 365 days, excepting every four hundredth year, which is to have 366 days. 17. The new style commenced in England in the year 1752, when it it was determined that the year should begin on the 1st day of January, instead of in March, as it had formerly. Note.-As the form of the year is various among different nations, so is likewise its beginning. The Jews, like other nations of the East, had a civil year, which commenced with the moon in September; and an ecclesiastical year, which began from the new moon in March. The Persians begin their year in the month answering to June. The Chinese and most of the Indian nations begin it with the first moon in March; and the Greeks with the new moon that happens next after the summer solstice. In England, the civil, or legal, year formerly commenced on the 25th of March, and the historical year on the first day of January. But, since the alteration of the style in 1752, as is above observed, the civil year in this country has likewise begun on the first of January. At the diet of Ratisbon, in 1700, it was decreed by the body of Protestants of the empire, that eleven days should be retrenched from the old style, in order to accommodate it to the new, and the same regulation has since passed into Sweden, Denmark, and England, where it was established by the 24th Geo. II. c. 23; which enacts, that the supputation, according to which the year of our Lord begins on the 25th day of March, shall not be used from and after the last day of December, 1751; and that from thenceforth the first day of January every year shall be reckoned the first day of the year, and that the natural day next and immediately following the 2nd day of September 1752 shall be called and reckoned the 14th day of September, omitting the eleven intermediate days of the common calendar; and the several natural days succeeding the 14th day, shall be called and reckoned in numerical order. The adoption of the Gregorian computation accordingly took place in 1752, and is now recognized throughout the United Kingdom. QUESTIONS FOR EXAMINATION. 1. What is chronology? 2. What are the principal divisions of time? 4. How is the beginning of the day reckoned? 5. How did the Jews and Romans divide their day and night? 9. How are months divided? 10. How is the periodical lunar month computed, and what is its length? 11. How is the synodical month reckoned? 12. What is the civil month? 13. Into how many months is the solar year divided? 14. How is the year measured, and of what did it formerly consist? 15. What was the length of the year as determined by Julius Cæsar, and what is its true length? 16. Explain the length of different years according to the new style. 17. When did the new style commence in England? LESSON THE SECOND. CYCLES. 1. The Romans reckoned by lustra, periods of five years, so called from a tax required to be paid every fifth year. 2. The Greeks reckoned by Olympiads, periods of four years, which derived their names from the public games celebrated every fourth year at Olympia in the Peloponnesus: they are computed from the year 776 before Christ. 3. Cycles are fixed intervals of time composed of the successive revolutions of a certain number of years; there are several cycles in use among chronologists. 4. The lunar cycle is a period of nineteen solar years, at the end of which interval the sun and moon return to very nearly the same part of the heavens. 5. The lunar cycle, on account of its utility in deter |