Thus among the earliest Egyptians the year was of 360 days, which were reckoned in the months, and five days were added each year, between the commencement of one and the end of the other, and called unlucky days. It was the belief of the Egyptians that these five days were the birthdays of their principal gods; Osiris being born on the first, Anieris (or Apollo) on the second, Typhon on the third, Isis on the fourth, Nephys (or Aphrodite) on the fifth. These appear to have some relation with similar unlucky days among the Greeks and Romans, and other nations. The 360 days of the Egyptian year were represented at Acantho, near Memphis, in a symbolical way, there being placed a perforated vessel, which each day was filled with water by one of a company of 360 priests, each priest having charge over one day in the year. A similar symbolism was used at the tomb of Osiris, around which were placed 360 pitchers, one of which each day was filled with milk. On the other hand, the 365 days were represented by the tomb of Osymandyas, at Thebes, being surrounded by a circle of gold which was one cubit broad and 365 cubits in circumference. On the side were written the risings and settings of the stars, with the prognostications derived from them by the Egyptian astrologers. It was destroyed, however, by Cambyses when the Persians conquered Egypt. They divided their year according to Herodotus into twelve months, the names of which have come down to us. Even with the 365 days, which their method of reckoning would practically come to, they would still be a quarter of a day each year short; so that in four years it would amount to a whole day, an error which would amount to something perceptible even during the life of a single man, by its bringing the commencement of the civil year out of harmony with the seasons. In fact the first day of the year would gradually go through all the seasons, and at the end of 1460 solar years there would have been completed 1461 civil years, which would bring back the day to its original position. This period represents a cycle of years in which approximately the sun and the earth come to the same relative position again, as regards the earth's rotation on its axis and revolution round the sun. This cycle was noticed by Firmicius. Another more accurate cycle of the same kind, noticed by Syncellus, is obtained by multiplying 1461 by 25, making 36,525 years, which takes into account the defect which the extra hours over 365 have from six. The Egyptians, however, did not allow their year to get into so large an error, though it was in error by their using sidereal time, regulating their year, and intercalating days, first according to the risings of the Pleiades, and after according to that of Sirius, the dog-star, which announced to them the approaching overflowing of the Nile, a phenomenon of such great value to Egypt that they celebrated it with annual fetes of the greatest magnificence.