In the Mesopotamian version of the Deluge the events occupied a period of a lunar month. There was a preparation period of two weeks, followed by 7 days of flooding plus 7 more days of staying in the Ark. The total period of staying in the Ark was 7 + 7 days.

The first biblical version based itself on the Mesopotamian pattern, but wanted to let the coming out from the Ark coincide with the beginning of a season. It has been observed that in the numerology of the Bible the most favorite number, after the universally almighty number 7, is the number 40. The Mesopotamian pattern consisted of an introductory period of 7 + 7 followed by a staying in the Ark of 7 + 7. In the Biblical version the periods become 7 + 40 and 40 + 7.

Hence, according to the basic biblical version Noah entered the Ark on the 17th day of month II, that is, on the 47th day of the year. The water began to pour on that evening, which in Hebrew terms was the beginning of the 18th day. There was flooding for 40 days and it took 7 days more for Noah to leave the Ark. Hence the total pattern consists of a period of 47 + 40 + 7 = 92 days, a season. The reference point is the beginning of the year and the terminal point, when Noah comes out of the Ark, either on the last day of the season or, more likely, on the first day of the new season. The question cannot be answered in a positive way because the four seasons of the year are different in length, but it can be assumed that a season lasts 91 days on the average.

The pouring of the water began on the 18th day of month II. Most commentaries on Genesis state that the Deluge began on the 17th day, but this is due to the influence of an incidental passage. Verse 7:13 states that Noah and his family entered the Ark on the 17th day, which means that the water came at the beginning of the 18th day, which would be the evening of the 17th day by our method of reckoning. Verse 7:12 which states that the water came on the 17th day reflects the mathematics of the fourth hand; I will explain later why the fourth hand had to add half a day to the length of the period of rising water.

The rise of the water was caused by a downpour that lasted 40 days. Subsequently the fourth hand because of its method of computation changed the references to a period of 40 days to "forty days and nights."

The original version did not mention the ebbing of the water, because the assumption was that the level of the sea remained higher. The 40 days of rainpour were followed by 7 days in which the mountains and hence land in general emerged from the water. In this respect the original version did not differ from the Mesopotamian version as related in the Epic of Gilgamesh.

Commentators do not try to explain why the Deluge started at the end of the 17th day of month II. It can be excluded that this date was linked with an astronomical phenomenon, because if it were so rabbinical commentators, quoted in the Talmud, could not have been debating whether the reference to the 17th day of month II should be interpreted as a reference to the 17th of the month Iyyar (April/May), which was the second month of the calendar employed by the Jews in the latest biblical period, or as a reference to the 17th of the month Marsheshvan (October/November), the eighth month according to the same calendar. Some rabbis reasoned that the Deluge must have come in the spring when rivers swell in Mesopotamia, and others that it must have come in the fall, which is the rainy season in the land of Israel. In modern terms it could be said that the rabbis wavered between the date of about May 1st and about November 1st. But what is important is that the rabbis saw what has been missed by modern commentators, namely, that the flooding began 47 days after the beginning of a season.

I have explained what no commentator to my knowledge up to now has succeeded to explain: namely the not trivial point that Noah entered the Ark on the 17th day of month II. Most commentators assume that the story of the Deluge contains figures selected more or less in a fanciful way and hence do not bother much with the date of the beginning of the flooding. But Cassuto, who as an intelligent fundamentalist assumes that the figures in the text have a rational explanation, declares that there must be a reason for the initial period of 47 days between the beginning of the year and the beginning of the Deluge, although he cannot find it. However, he points out that these 47 days are divided into 40 + 7 days. >From verse 7:4 we learn that Noah was given a 7-day warning: "In seven days' time I will cause to rain upon the earth for forty days and forty nights." Cassuto suggests that possibly the preceding 40 days were dedicated to the construction of the Ark. He could be right, but there is no need to decide whether this suggestion is sound or not. The important point is that the Deluge was preceded by a period of 40 + 7 days. Then the rain fell for 40 days. The period from the end of the rain to the exit from the Ark must have been 7 days as in the version of the Epic of Gilgamesh.

The original biblical version contained a perfect balance: 40 + 7 days from the beginning of the year to the closing of the Ark; 40 + 7 days from the closing to the opening of the Ark. 94 days are a season.

[*** missing text ****] version counted 14 days from the beginning of the month to the beginning of the sea and rain storm, and 14 days of staying in the Ark. The biblical version adapted this reckoning to the Hebrew unit of lineal measurement. The Hebrews before the Exile computed by Roman cubits (= 443.9182 mm.) which the Talmud calls cubits of Moses. Calculating in Roman cubits the height of the water is: 40~x~40~x~14 Roman cubits = 22,400 cubits In the new system a degree of meridian was 250,000 Roman cubits, and a great circle passing through the poles 90,000,000 cubits (39,952,637 meters). In calculating the radius, they assumed p = 3 1/8, which is the common practical value in cuneiform mathematical texts. Hence they assumed that the radius of the Earth is 14,400,000 cubits. The original version of the Hebrew deluge story implied that the radius of the pre-diluvial world, under the Egyptian system, had been 14,400,000 - 22,400 = 14,377,600 Roman cubits. This calculation implies that the Egyptian system gave dimensions that are about 1/641 less.

                            Egyptian system           New system
 
radius of the Earth
in meters
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radius of the Earth           14,377,600               14,400,000
in Roman cubits
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great circle in meters        39,890,312               39,952,637
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great circle
in Roman cubits               89,859,600               90,000,000
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degree of meridian
in meters                        110,806.421              110,979.55
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degree of meridian
in Roman cubits                  249,610                  250,000
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height of water
in cubits                                                  22,400