706 CHRONOLOGY.

the most celebrated of them all, mentions nothing like a formalcalendar in any part of his writings. In the most early periods,the only measurement of time was by the seasons, the involutionsof the sun and moon ; and many ages seem to have elapsed beforethe mode of computation by dating events t ame into general use.Several centuries intervened between this era of the ol\ mpic gamesand the first historians : and several more between these and thefirst authors of chronology. When time first began to be reckon-ed, we find its measures very indeterminate. The succession ofJuno’s priestesses at Argos sorted Ilellanicus for the regulation ofhis narrative ; while Ephorus reckoned his matters by generations,Even in the histories of Herodotus and Times didos, we find noregular dales for the events recorded. No attempt appears to havebeen made to establish a fixed era, until the time of Ptolemy Phila-delphia,, who attempted it by comparing and correcting the datesof the olympiads, the kings of Sparta, and the succession of thepriestesses of Juno at Argos. Eratosthenes and Apollodorus di-gested the events recorded by them according to the succession ofthe olympiads and of 'the Spartan kings. The uncertainty of themeasures of time in the most early periods renders the histories ofthose times equally uncertain ; and even after the invention ofdates and eras, we find the ancient historians very inattentive tothem, and inaccurate in their computations. Frequently their erasand years wen: reckoned differently without their being sensibleof it, or ijt least without giving the reader any information con-cerning it; a circumstance which has rendered the fragments oftheir works now remaining of very little use to posterity. TheChaldean and Egyptian writers are generally acknowledged to hefabulous ; and Strabo acquaints us, that Diodorus, Siculus, and theother early historians ol Greece, were ill informed and credulous.Hence the disagreement among the ancient historians, and the ex-treme confusion and contradiction we meet with on comparingtheir works. Ilellanicus and Acusilaus disagreed about their ge-nealogits; the latter rejected the traditions of Hesiod. Tinnitusaccused Epliorus of falsehood, and the rest of the world accusedTiinteus. The most fabulous legends were imposed on the worldby Herodotus ; and even Thucydides and Diodorus generally ac-counted able historians, have been convicted of error. Thechronology of the Latins is still more uncertain. The records ofthe Romans were destroyed by the Gauls; and Kahilis Pictor, themost ancient of their historians was obliged to borrow the greatestpart of his information from the Greeks. In other European na-tions the'chronology is still more imperfect and of a later dale;and even in modern times, a considerable degree of confusion andinaccuracy lias arisen from want of attention in the historians, toascertain the dates and epochs with precision. It is obvious, there-fore, how necessary a proper system of chronology must be forthe right understanding of history, and likewise how very difficultit must be to establish such a system. In that, however, severallearned men have excelled, particularly Julius Africamis, Euse-bius of Ciesarea, George Cvncelle, John of Antioch, Dennis,Vetau, Cluviar, Calvisius, I’sslier, Simsoii, Marsliam, Blair, Play-fair, &c. Chronology is founded, 1. On agronomical observa-tions, particularly ot the eclipses of the sun and moon, combinedwith the calculations of the eras and years of different nations. 2,The testimonies of credible authors. 3. Those epochs in history,which are so well attested and determined, that they have neverbeen controverted. 4. Ancient medals, coins, monuments, andinscriptions. None of these, however, can be sufficiently intelligi-ble without an explanation of the first part, which considers the di-visions offline, ami of which therefore we shall proceed to treat of.

Of the Divisions of Time.

Of Days. The most obvious division of time is derived from theapparent revolutions of the celestial bodies, particularly of the sun,which, by the vieis-ijudes of day and night becomes evident tothe most barbarous and ignorant nations. In strict propriety ofspeech the word day signifies only that portion of time duringwhich the sun diffuses light on any part of the earth; lnit in themost comprehensive sense, it includes the night also, and is calledbv elironologers a civil dav ; by astronomers ; natural, and some--times an artificial, day. By a civil day is meant the interval be-twixt the Min’s departure from any given point in the heavens•and his return to it; with as much more as answers to his diurnalmotion eastward, which is at the rate of 5!) minutes and eightseconds of a degree, or three minutes and 57 seconds of time. It

is also called a solar day, and is longer than a siderial one, inso-much that, if the former be divided into 24 equal parts or hours,the latter will consist only of 23 hours 56 minutes. The apparentinequality ol the sun’s motion, likewise arising from the obliquityof Hie ecliptic, produces another inequality in the length of thedays; and hence the difference betwixt real and apparent time,so that the apparent motion of the sun cannot always be a truemeasure of duration. Those inequalities, however, are capable ofbeing reduced to a general standard, w'liiih furnishes an exactmeasure throughout the year; whence arises the differences be-tween mean and apparent time. See Astronomy. The com-mencement and conclusion of the day have been very differentlyreckoned by difierent nations. T he beginning of the dav wascounted from sunrise by the Babylonians, Syrians, Persians", andIndians. The civil day of the Jews was begun from sunrise, andtheir sacred one from sunset; the latter mode of computationbeing followed by the Athenians, Arabs, ancient Gauls, and otherEuropean nations. According to some, the Egyptians began theirduy at sunset, while others are of opinion that they computed fromnoon or from sunrise; Pliny informs us that they computed theircivil day from one midnight to another. It is probable, however,that they had difierent inodes of computation in difierent provincesor cities. The Atisoniaiis, the most ancient inhabitants of Italy,computed the day from midnight; and the Astronomers of Cathayand Oighur in the East Indies reckoned in the same manner. Thismode of computation was adopted by Hipparchus, Copernicus,and other astronomers, and is now iu common use among our-selves. The astronomical day, however, as it is called, on ac-count of its being used in astronomical calculations, commences atnoon, and ends at the same time the following day. The Mo-hammedans reckon from one twillight to another. A very singu-lar method of computation takes place in Italy. The civil daycommences at some indeterminate point after sunset; whence thetime of noon varies with the season of the year. At the summersolstice, the clock strikes 16 at noon, and 19 at the time of the win-ter solstice. Thus the length of each day differs by several mi-nutes from that immediately preceding or following it. Phis vari-ation requires a considerable difficulty in adjusting their time byclocks. It is accomplished, however, by a sudden movement whichcorrects the difference when it amounts to a quarter of an hour;and this it does sometimes at the end of eight days, sometimes atth« end of 15, and sometimes at the end of 40. Information of allthis is given by a printed calendar, which announces, that from the16th of February, for instance, to the 24th, it w ill be noon at aquarter past 18 ; from the 24th of February to the 6th of March,it will be noon at 18 o’clock precisely; from the first of June tothe 13th of July, the hour of noon will be at 16 o’clock ; on the13th of July it will be at half an hour after 16; and so on through-out the different months of the year. The subdivisions of the dayhave not been less various than the computations of the day itself.The most obvious division, and which could at no time, nor in noage, be mistaken, was that of morning and evening. In process oftime the two intermediate points of noon and midnight were detersmined : and this division into quarters was in use long before theinvention of hours. From this subdivision probably arose themethod used by the Jews and Romans of dividing the day aminight into four vigils or watches. The first began at sun-rising, orsix in the morning; the second at nine; the third at 12; and thefourth at three in the afternoon. In like maimer the night was di-vided into four parts; the first beginning at six in the evening, thesecond at nine, the third at 12, and the fourth at three in the morn-ing. The first of these divisions was called bv the Jews the thirdhour of the day ; the second the sixth ; the third the ninth ; andthe fourth the 1 Jtli, and sometimes the 11th. Another division inuse, among these nations as well as the Greeks, was that whichreckoned the first quarter from sunset to midnight ; the secondfrom midnight to sunrise; the third or morning watch, frommorning to noon ; and the fourth from noon to sunset. At whattime the more minute subdivision of the day into hours tirst com-menced, is uncertain. It does not appear from the w ritings ofMoses, that he was acquainted with it, as he mentions only themorning, mid-day, evening,and sunset. Hence we may conclude,that the Egyptians at that time knew nothing ol it, as Moses waswell skilled in their learning. According to Herodotus, theGreeks received the know ledge of the 12 hours of the dav fromtlie Babylonians. It is probable, however, that the division was

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