At length the _Egyptians_, for the sake of Navigation, applied themselves to observe the Stars; and by their Heliacal Risings and Settings found the true Solar year to be five days longer than the Calendar year, and therefore added five days to the twelve Calendar months; making the Solar year to consist of twelve months and five days. _Strabo_ [65] and [66] _Diodorus_ ascribe this invention to the _Egyptians_ of _Thebes_. _The _Theban_ Priests_, saith _Strabo_, _are above others said to be Astronomers and Philosophers. They invented the reckoning of days not by the course of the Moon, but by the course of the Sun. To twelve months each of thirty days they add yearly five days._ In memory of this Emendation of the year they dedicated the [67] five additional days to _Osiris_, _Isis_, _Orus_ senior, _Typhon_, and _Nephthe_ the wife of _Typhon_, feigning that those days were added to the year when these five Princes were born, that is, in the Reign of _Ouranus_, or _Ammon_, the father of _Sesac_: and in [68] the Sepulchre of _Amenophis_, who Reigned soon after, they placed a Golden Circle of 365 cubits in compass, and divided it into 365 equal parts, to represent all the days in the year, and noted upon each part the Heliacal Risings and Settings of the Stars on that day; which Circle remained there 'till the invasion of _Egypt_ by _Cambyses_ King of _Persia_. 'Till the Reign of _Ouranus_, the father of _Hyperion_, and grandfather of _Helius_ and _Selene_, the _Egyptians_ used the old Lunisolar year: but in his Reign, that is, in the Reign of _Ammon_, the father of _Osiris_ or _Sesac_, and grandfather of _Orus_ and _Bubaste_, the _Thebans_ began to apply themselves to Navigation and Astronomy, and by the Heliacal Risings and Settings of the Stars determined the length of the Solar year; and to the old Calendar year added five days, and dedicated them to his five children above mentioned, as their birth days: and in the Reign of _Amenophis_, when by further Observations they had sufficiently determined the time of the Solstices, they might place the beginning of this new year upon the Vernal Equinox. This year being at length propagated into _Chaldæa_, gave occasion to the year of _Nabonassar_; for the years of _Nabonassar_ and those of _Egypt_ began on one and the same day, called by them _Thoth_, and were equal and in all respects the same: and the first year of _Nabonassar_ began on the 26th day of _February_ of the old _Roman_ year, seven hundred forty and seven years before the Vulgar _Æra_ of _Christ_, and thirty and three days and five hours before the Vernal Equinox, according to the Sun's mean motion; for it is not likely that the Equation of the Sun's motion should be known in the infancy of Astronomy. Now reckoning that the year of 365 days wants five hours and 49 minutes of the Equinoctial year; the beginning of this year will move backwards thirty and three days and five