Now, although a great many credible facts are to be gathered from the above authorities from which we are justified in making the general deduction that the period of dynastic civilization lasted between four and five thousand years, they none of them help to fix an exact date for the reign of the first dynastic king of Egypt, who, by general consent, is said to have been =Menȧ= or =Menes=. If Manetho’s List were trustworthy, the difficulty would be settled, but unfortunately one version of it makes 561 kings reign in 5,524 years, whilst another gives the number of the kings as 361, and their total reigns as 4,480 or 4,780 years. Many Egyptologists have accepted Manetho’s statements with modifications, but others have tried to work out more accurate results, astronomically, by the use of the =Sothic Period=. It has already been said that the Sothic Period of 1,460 years is equal to 1,461 vague, or calendar, years, and it is argued that, if we can find mentions of the risings of Sothis (Sirius, or the Dog-star) expressed in terms of the vague year, and if we can also fix a date for the beginning or end of a Sothic Period, it will be possible to arrive at fixed points in Egyptian chronology. Fortunately some three or four mentions of the rising of Sothis are known in the inscriptions, and thanks to =Censorinus=, who wrote his work (_De Die Natali_) A.D. 238, it is known that a Sothic Period came to an end A.D. 139.[31] If this be so, it is clear that the Sothic Period to which he refers began in B.C. 1321, the one before that in B.C. 2781, the one previous in B.C. 4241, and so on. The next step is to work out the mentions of the risings of Sothis which are expressed in terms of the vague, or calendar, year, and, provided that the statement of Censorinus be trustworthy and the calculations of modern investigators be correct, it is possible to assign a date in ordinary Julian years to such risings of Sirius. Want of space renders it impossible to discuss here the various systems of chronology which have been formulated by Egyptologists and others, but the dates proposed by the principal authorities for some of the dynasties may be thus grouped:— DYNASTY. DATES PROPOSED. 1. 2. 3. 4. 5. 6. I 5869 5702 5613 5004 4400 3315 III 5318 5147 5058 4449 3966 2895 VI 4426 4402 4310 3703 3300 2540 XII 3703 3404 3315 2851 2466 2000 XVIII 1822 1655 1796 1703 1700 1580 XIX 1473 1326 1404 1462 1400 1320 XX 1279 1183 1195 1288 1200 1200