PUBLISHED UNDER THE SUPERINTENDENCE OF THE SOCIETY FOR THE DIFFUSION OF USEFUL KNOWLEDGE. COMMITTEE. Chairman-H. BROUGHAM, Esq., F.R.S., M.P. Vice Chairman-LORD JOHN RUSSELL, M.P. Treasurer-WILLIAM TOOKE, Esq., F.R.S. Rt. Hon. J. Abercrombie, M. P. | M. D. Hill, Esq. W. Allen, Esq., F.R.S. Lord Althorp, M.P. Rt. Hon. Lord Auckland. R. Otway Cave, Esq., M.P. Hon. G. Agar Ellis, M.A., M.P. T. F. Ellis, Esq., M.A. Ashburton-J.F.Kingston, Esq. | Birmingham Local Association. Rev. John Corrie, Chair. man. Paul Moon James, Esq., Treasurer. Hon. Jos. Parkes, Esq. W. Redfern, EsqSecs. Bristol-J. N. Sanders, Esq., Chairman. J. Reynolds, Esq., Treas. Rev. Prof. Henslow, M.A., Rev. John Lodge, M.A. ΜΑ. Rowland Hill, Esq. B. H. Malkin, Esq., M.A. Edinburgh-R. Greville, LL.D. | Mr. T. Atkinson, Hon. Sec. Hull-DI. Sykes, Esq., M.P. Keighley, Yorkshire Rev. T. Dury, M.A. Launceston-Rev J. Barfitt. Leamington Spa-Dr. Loudon. Leeds-Benjamin Gott, Esq. J. Marshall, Jun., Esq. Lewes J. W. Woollgar, Esq. Liverpool Local Association. Dr. Traill, Chairman. J. Mulleneux, Esq., Treas. Rev. W. Shepherd. J. Ashton Yates, Esq. Maidenhead-R. Goolden, Esq., F.L.S. THOMAS COATES, Secretary. Rt. Hon. Lord Nugent. M.P. T. Spring Rice, Esq., M.P., Dr. Roget, Sec. R.S. Rt. Hon. Lord Suffield. H. Waymouth. Esq. Manchester Local Association. G.W.Wood, Esq., Chairman. Hon. Sec Sir G. Philips, Bart., M.P. Portsmouth- E. Carter, Esq. Rev. Dr. Inman, Nav. Col. Sheffield-J. H. Abraham, Esq. Shrewsbury-R. A. Slaney, Esq., M.P. South Petherton-John Nicholetts, Esq. Tavistock-Rev. W. Evans. Wolverhampton - J. Pearson, Worcester-Dr. Corbett, M.D. The SUSSEX SESSIONS in the British Almanac for 1830 are incorrectly given. They SUSSEX SESSIONS, 1830, Petworth, January 12, April 20; Horsham, July 13; Chichester, October 19. Eastern Division, Lewes, January 15, April 23, July 16, Oct. 22. COMPANION TO THE ALMANAC. PART I. INFORMATION CONNECTED WITH THE CALENDAR, THE CELESTIAL CHANGES, AND THE NATURAL PHENOMENA OF THE YEAR. I. THE ERAS OF ANCIENT AND MODERN TIMES, AND OF VARIOUS COUNTRIES, EXPLAINED; With a view to the comparison of their respective dates. In the earliest stages of society, some division of time must have been necessary, and some means devised by men in the most savage state, to communicate to each other the period of undertaking, in concert, a hunt or a predatory excursion. But in such a condition the views of men do not extend far, and very limited periods would therefore suffice. The division of day and night, and the scarcely less obvious distinction of new and full moon, might have served to mark the lapse of time for ages; and, although in all climates the alternations of summer and winter, and of wet and dry periods, must have obtruded themselves on the feelings of the most unobserving, it was probably not until the practice of agriculture had afforded men leisure for reflection, that any accurate observations were made on the duration of the seasons, or means used to ascertain the periods of their return. We see, at the present time, that many societies of men, who live only by hunting and fishing, have no exact knowledge of duration of time beyond that of a moon or season, and designate a term of five or of fifty years, equally as a long time. All agricultural nations are aware of the return of the same seasons after a lapse of twelve or thirteen moons; but many years must have elapsed before the length of a solar year was accurately determined. Less civilized nations still continue to compute their time in part by the motions of the moon; and this was the mode of the Greeks, and of the Romans until the correction of Julius Cæsar, but the subject was so little understood even in his time, that an error of several days crept into the Roman calendar soon afterwards, requiring another reformation. It will render the comparison of eras much easier, if we give some account of what is meant by a solar and a lunar year. A solar year is that space of time during which all the seasons have their course. This takes place in 365 days, 5 hours, 48 minutes, and 49 seconds; and an approximation to that time has been adopted by those nations which have had sufficient astronomical science to determine it. But as it would be impracticable to begin every new year at a different hour of the day, which would be necessary if the perfect year should always be completed before the commencement of a new one, 365 days have been taken as the length of a year, leaving the odd hours and minutes to accumulate until they amount to a whole day, when they are added to the year, making what is called a leap year, or intercalary year, of 366 days. The various ways of doing this will be detailed when we speak of the different eras. Some nations still use a year of 365 days without any intercalation; and this is called a vague, or erratic year, because its commencement varies through all the different seasons. A lunar year consists of 12 moons, or 354 days. This may be convenient enough for short periods, but is so ill adapted for the computation of a civilized nation, that none but Mahometans have continued in the use of it even for a little time. It suits the course of time so ill, that its commencement varies, in a few years, through all the seasons; and many men, amongst the nations which use it, can remember the fasts and festivals altering from summer to winter, and again from winter to summer, and their seed-time and harvest alternately wandering from the beginning of the year to the end. The luni-solar year is that in which the months are regulated according to the course of the moon, but to which from time to time a month is added, whenever the year would range too widely from its original situation. This year is inconvenient from its varying duration; but as, in a long course of years, the months remain nearly at the same situation, it is less objectionable than the pure lunar year. It was the mode of computation of the Greeks and Romans, and is even now that of the Chinese, Tartars, Japanese, and Jews. All these varying modes render the comparison of dates much more difficult than it appears to be at the first view. We shall endeavour so far to simplify the calculation as to enable any arithmetician to compute, within a day or two, the eras of every nation, and to reduce them to the Christian era.* THE ROMAN YEAR. The Roman year, in its arrangement and division, is that on which our year is entirely founded. The Romans reckoned their time from the date which some of their antiquaries chose to assign for the founding of Rome, viz. the 21st of April, in the 2nd year of the 6th Olympiad, or 754 B.C. This era is designated by the letters A.U.C., or ab urbe condita, “from the building of the city." The first year used by them, and attributed to Romulus, consisted of ten months, from March to December, or 304 days. A year * "The Calendar, and its successive Reforms," was explained in a short paper in the Companion for 1828. Some parts of the information there given are necessarily repeated in this article, which is intended to be as com plete and practical as the subject will allow. |