Imatges de pągina
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13 1804-5 14 1805-6 The Mohammedan Era, or Era of the Hegira, dates from the flight of Mohammed to Medina, which event took place in the night of Thursday, the 15th of July, A. D. 622. The era commences on the following day, viz., the 16th of July. Many chronologists have computed this era from the 15th of July, but Cantemir has given examples, proving that, in most ancient times, the 16th was the first day of the era; and now there can be no question, that such is the practice of Mohammedans. The year is purely lunar, consisting of 12 months, each month commencing with the appearance of the new moon, without any intercalation to bring the commencement of the year to the same season. It is obvious, that, by such an arrangement, every year will begin much earlier in the season than the preceding, being now in summer, and, in the course of 16 years, in winter. Such a mode of reckoning, so much at variance with the order of nature, could scarcely have been in use beyond the pastoral and semi-barbarous nation by whom it was adopted, without the powerful aid of fanaticism; and even that has not been able to prevent the use of other methods by learned men in their computations, and by governments in the collection of revenue. It will also be remarked, that, as the Mohammedans begin each month with the appearance of the new moon, a few cloudy days might retard the commencement of a month, making the preceding month longer than usual. This, in fact, is the case, and two parts of the same country will sometimes differ a day in consequence; although the clear skies of those countries where Islamism prevails rarely occasion much inconvenience on this head. But in chronology and history, as well as in all documents, they use months of 30 and 29 days, alternately, making the year thus to consist of 354 days: eleven times in 30 years, one day is added to the last month, making 355 days in that year. Consequently the average length of a year is taken at 354 days, the 12th of which is 29, differing from the true lunation very little more than 3 seconds, which will not amount to a day in less than 2260 years-a degree of exactness which could not have been attained without long continued observa

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tions. The intercalary year of 355 days Occurs on the 2d, 5th, 7th, 10th, 13th, 15th, 18th, 21st, 24th, 26th, and 29th years of every 30 years. Any year being given, to know whether it be intercalary or not, divide by 30, and if either of the above numbers remain, the year will be one of 355 days. To reduce the year of the Hegira to that of the Christian, the following mode, though not strictly accurate, is sufficiently so for most purposes. The Mohammedan year being a lunar year of 354 days, 33 such years will make 32 of ours. We have only, then, to deduct one year for each 33 in any given number of Mohammedan years, and add 622 (the year of our era, from which their computation commences), and we obtain the corresponding year of the Christian era.

Indian Chronology. The natives of India use a great variety of epochs, some of which are but little understood, even by themselves, and almost all are deficient in universality and uniformity, so that the same epoch, nominally, will be found to vary many days, or even a year, in different provinces. The solar, or, more properly, the sidereal year, is that which is most in use for public business, particularly since the introduction of European power into India. This year is calculated by the Indian astronomers at 365 days, 6 hours, 12 minutes, 30 seconds, or, according to others, 36 seconds. Therefore, in 60 Indian years, there will be a day more than in 60 Gregorian years. The difference arises from not taking into consideration the precession of the equinoxes, which is equal, in reality, to something more than 20 minutes, though by them calculated at 23 minutes. The lunisolar computation is not at present so common as it formerly was, although still much used in some parts of India, and common every where in the regulation of festivals, and in domestic arrangements. Both the solar and luni-solar forms may be used with most of the Indian eras, though some more particularly affect one form and some the other. The luni-solar mode varies in different provinces, some beginning the month at full moon, others at new moon. We shall describe that beginning by the full moon, which is used in Bengal; the other method will be easily understood when this is known. Each year begins on the day of full moon preceding the beginning of the solar year of the same date. The months are divided into halves, the first of which is entitled badi, or dark, being from the

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full moon to the new; and the last, sudi, or bright, from new to full moon. These divisions are sometimes of 14 and sometimes of 15 days, and are numbered generally from 1 to 15, though the last day of the badi half is called 15, and that of sudi is called 30. By a complicated arrangement, a day is sometimes omitted, and again a day is intercalated, so that, instead of going on regularly in numerical order, these days may be reckoned 1, 1, 2, 3, 4, 5, 6, 7, 8, 10. The subject is enveloped in some obscurity; and it will be, perhaps, sufficient to observe, that the time of a lunation is divided into 30 parts, called tiths, and, when two tiths occur in the same solar day, that day is omitted in the lunar reckoning, and restored by intercalation at some other period. When two full moons occur in one solar month, the month also is named twice, making a year of 13 months. In the case, also, of a short solar month, in which there should be no full moon, the month would be altogether omitted. All these circumstances render the luni-solar computation a matter of much difficulty; and to reduce it exactly to our era, would require a perfect knowledge of Hindoo astronomy. But as the solar reckoning is by far the most general, we shall only observe, that the lunar month precedes the solar month by a lunation at most; and consequently a lunar date may be nearly known from the solar time, which is of easy calculation. The eras which are generally known are the following:

The Caliyug. This era is the most ancient of India, and dates from a period 3101 years before Christ. It begins with the entrance of the sun into the Hindoo sign Aswin, which is now on the 11th of April, N. S. In the year 1600, the year began on the 7th of April, N. S., from which it has now advanced 4 days, and, from the precession of the equinoxes, is still advancing at the rate of a day in 60 years. The number produced by subtracting 3102 from any given year of the Caliyug will be the Christian year in which the given year begins.

The Era of Salivahana may be joined here to that of the Caliyug, being identical with it as to names of months, divisions and commencement, and differing only in the date of the year, which is 3179 years more recent than that, and therefore 77 years since our era. It is much used in the southern and western provinces of India, and papers are frequently dated in both eras. The years of this era are called Saca. The number 77 must

be added to find the equivalent year of the Christian era. Both these eras are most commonly used with solar time.

The Era of Vicramaditya, which has its name from a sovereign of Malwa, may also be placed here, as it uses the same months as the two above mentioned; but it is more generally used with lunar time. This era is much employed in the north of India, and its years are called Samvat. It began 57 years before Christ; and that number must be deducted to bring it to our era. In Guzerat, this era is used, but it begins there about the autumnal equinox. The months all begin on the days of the entrance of the sun into a sign of the Hindoo zodiac, and they vary from 29 to 32 days in length, though making up 365 days in the total, in common years, and 366 in leap years. The intercalation is made when and where it is required, not according to any arbitrary rule, but by continuing the length of each month until the sun has completely passed each sign. This will bring about 26 leap years in every century. It would require long and complicated calculations to find exactly the commencement and duration of each month, but we shall not err more than a day or two by considering them to be of 30 and 31 days alternately.

The Bengalee year appears to have been once identical with the Hegira; but the solar computation having subsequently been adopted, of which the years exceed those of the Hegira by 11 days, it has lost nearly 11 days every year, and is now about 9 years later, the year 1245 of the Hegira beginning in July, 1829, and the Bengalee year 1236 beginning 13th of April of the same year. The number 593 must be added to bring this to the Christian era.

The Chinese, like all the nations of the north-east of Ásia, reckon their time by cycles of 60 years. Instead of numbering them as we do, they give a different name to every year in the cycle. As all those nations follow the same system, we shall detail it here more particularly. They have two series of words, one of ten, and the other of twelve words; a combination of the first words in both orders is the name of the first year; the next in each series are taken for the second year; and so to the tenth in the eleventh year, the series of ten being exhausted, they begin again with the first, combining it with the eleventh of the second series; in the twelfth year, the second word of the first series is combined with the twelfth of the second; for the thirteenth year,

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30 kƒ 60 k m. The series of 10 is designated in China by the name of teen kan, or celestial signs. The Chinese months are lunar, of 29 and 30 days each. Their years have ordinarily 12 months, but a 13th is added whenever there are two new moons while the sun is in one sign of the Zodiac. This will occur seven times in 19 years. The boasted knowledge of the Chinese in astronomy has not been sufficient to enable them to compute their time correctly. In 1290 A. D., the Arab Jemaleddin composed a calendar for them, which remained in use until the time of the Jesuit Adam Schaal, who was the director of their calendar until 1664. It then remained for five years in the hands of the natives, who so deranged it, that, when it was again submitted to the direction of the Christians, it was found necessary to expunge a month to bring the commencement of the year to the proper season. It has since that time been almost constantly under the care of Christians. The first cycle, according to the Romish missionaries, began February 2397 B. C.* We are now, therefore, in the 71st cycle, the 27th of which will begin in 1830. To find out the Chinese time, multiply the elapsed cycle by 60, and add the odd years; then, if the time be before Christ, subtract the sum from 2398; but if after Christ, subtract 2397 from it; the remainder will be *Dr. Morrison carries it back to the 61st year of Hwang-te,2596 B. C., making the present year to fall in the 74th cycle; but, according to the celebrated historian Choofootze, Hwang-te reigned about 2700 B. C., making 75 cycles from that period, which is, probably, more correct than

either of the above statements.

now emperor.

The Japanese have a cycle of 60 years, like that of the Chinese, formed by a combination of words of two series. The series of ten is formed of the names of the elements, of which the Japanese reckon five, doubled by the addition of the masculine and feminine endings je and to. The cycles coincide with those of the Chinese; but a name is given to them instead of numbering them. Their years begin in February, and are luni-solar, of 12 and 13 months, with the intercalations as before mentioned under the head of China. The first cycle is said to begin 660 B. C.; but this cannot be correct, unless some alteration has taken place, as the Chinese cycle then began 657 B. C. We know, however, too little of Japan to pronounce positively respecting it; but thus far it is certain, that the cycle now coincides with that of the Chinese.

To an article of this nature it may not be thought superflous to append a slight notice of the manner in which some of the aboriginal tribes of America reckoned their time before its discovery by the natives of Europe. The science of astronomy seems to have advanced there to a much greater extent than is commonly imagined. The extraordinary accuracy of the Mexicans in their computations, surpassing that of the Europeans of their time, cannot be accounted for otherwise than by the supposition that they had derived it from some people more civilized than themselves; and would appear incredible, if not well attested by Spanish authors of the 15th century, as well as by many hieroglyphic almanacs yet remaining, of undoubted antiquity. The Peruvians and Muyscas had lunar years of great accuracy also; but this is less surprising, as the phases of the moon

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are sufficiently visible to the eye, and their returns frequent. We shall detail that of the Mexicans only.

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seconds, being only 2 3919" shorter than the truth. As the wanton destruction of the Mexican monuments and hieroglyphThe year of the Mexicans consisted of ic records, by their cruel and barbarous 365 days; it was composed of eighteen conquerors, has left little to study, and months of twenty days each, and five ad- the extermination of the Mexicans of ditional, called nemontemi, or void. At superior order has done away with their the end of a cycle of 52 years, 13 days system, we shall not detail the names of were added, and at the end of another their months and particulars of their cycles, cycle 12 days, and so on, alternately, which afford striking coincidences with making an addition of 25 days in 104 those of the Tartars, Japanese, &c. We years. This made the mean year to con- shall only add, that their first cycle began sist of 365 days, 5 hours, 46 minutes, 93 in the month of January, A. D. 1090.

List of the Correspondence of Eras with the Year 1830.

[When the commencement of the year coincides with the Christian year, that alone will be given; when it begins at a different season, the month in which the 1st of January, 1830, occurs will be also stated.]

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5th book of the odes of Horace. All the odes in this book, however, are not satirical, and Scaliger therefore supposes, that the name here signifies an appendix to the odes; the epodes having been joined to the other works of the poet after his

death.

EPOPEE. (See Epic.)

EPOPTE (from the Greek inì and onтoμαι, I see); inspectors, or spectators, i. e., initiated; a name given to those who were admitted to view the secrets of the greater mysteries, or religious ceremonies of the ancient Greeks.

EPROUVETTE; the name of an instrument for ascertaining the strength of fired gunpowder, or of comparing the strength of different kinds of gunpowder. One of the best, for the proof of powder in artillery, is that contrived by doctor Hutton. It consists of a small brass gun, about 2 feet long, suspended by a metallic stem, or rod, turning by an axis, on a firm and strong frame, by means of which the piece oscillates in a circular arch. A little below the axis, the stem divides into two branches, reaching down to the gun, to which the lower ends of the branches are fixed, the one near the muzzle, the other near the breech of the piece. The upper end of the stem is firmly attached to the axis, which turns very freely by its extremities in the sockets of the supporting frame, by which means the gun and stem vibrate together in a vertical plane, with a very small degree of friction. The piece is charged with a small quantity of powder (usually about two ounces), without any ball, and then fired; by the force of the explosion, the piece is made to recoil or vibrate, describing an arch or angle, which will be greater or less according to the quantity or strength of the powder.

EPSOM; a place in England, 15 miles south of London, in Surrey; population, 2890. It is celebrated for its medicinal springs, of a purgative quality, and for the downs, on which horse-races annually take place. Near it Henry VIII built a splendid palace, called Nonsuch.

EPSOM SALT (Sulphate of magnesia, cathartic salt) appears in capillary fibres or acicular crystals; sometimes presents minute prismatic crystals. The fibres are sometimes collected into masses; and it also occurs in a loose, mealy powder: its color, white, grayish or yellowish: it is transparent, or translucent, with a saltish, bitter taste. It is soluble in its own weight of cold water, and effloresces on exposure to the air. It is composed of water, sulphu

ric acid and magnesia. It is found covering the crevices of rocks, in caverns, old pits, &c., in the vicinity of Jena, on the Harz, in Bohemia, &c., in mineral springs, in several lakes in Asia, and in sea-water. It is obtained for use from these sources, or by artificial processes, and is employed in medicine as a purgative. The English name is derived from the circumstance of its having been first procured from the mineral waters at Epsom, England. (See Magnesia.)

EQUATION, in algebra, is the expression of the equality of different indications of the same magnitude; as, for instance, 9 and 2 are equal to 11, in mathematical characters is expressed thus:9+2-11; or, 3 from 4 leave 1, is 4-3 1. An equation may contain known quantities and unknown quantities. The latter are usually indicated by the last letters of the alphabet; and it is one of the main objects of mathematics to reduce all questions to equations, and to find the value of the unknown quantities by the known, which is sometimes a difficult, but, at the same time, interesting operation; because x, or the unknown quantity, may be given under so involved a form as to require the greatest tact to determine its value. The work of Meier Hirsch, already mentioned in the article Algebra, is perhaps the best collection of equations for solution. There must always be as many equations as there are unknown quantities; and it is not always easy to form these from the question proposed. The equation is called simple, quadratic, cubic, bicubic, of the fifth, &c. degree, according to the exponent of the unknown quantity; for instance (x24cdy+xp) x4-pq-sin 4p, is an equation of the sixth degree. Equations are the soul of all algebraical operations.

EQUATION OF PAYMENTS, in arithmetic, is the finding the time to pay at once several debts due at different times, and bearing no interest till after the time of payment, so that no loss shall be sustained by either party. The rule commonly given for this purpose is as follows:Multiply each sum by the time at which it is due; then divide the sum of the products by the sum of the payments, and the quotient will be the time required. Thus, for example, A owes B £190, to be paid as follows; viz. £50 at 6 months, £60 at 7 months, and £80 at 10 months: what is the equated time at which the whole ought to be paid, that no loss may arise, either to debtor or creditor? By the rule,

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