But, though we are unable to say how the population _did increase in point of fact_, we can easily show how it _may have increased_. For this purpose we venture to lay before our readers a calculation by which we account for the fact in a manner perfectly conformable to all the “data of the Pentateuch”. First, as regards the number of generations. Since a generation is descent from father to son, the length of time to be allowed for a generation will be determined in each particular case by the age of the father when the son is born. This of course will vary for different families, and even for different members of the same family. We may, however, fairly suppose that, among the Hebrew people in Egypt, taking one family with another, every man on an average had children born to him at the age of 32. Thus 32 years would be the average length of each generation. The males of the first generation, as we have before seen, were all living at least three years before the descent into Egypt, or 218 years before the Exodus. For each succeeding period of 32 years we must add, according to our calculation, one generation more. In 218 years there are just six periods of 32 years each, and 26 years over. Therefore the whole of the seventh generation must have been living 26 years before the Exodus. Next we may estimate the number of males in the first generation at a hundred and twenty-five. To this generation would belong all those, who, at the time of the descent, were above the age of three, and under the age of thirty-five. Those who were three, or less than three, should not be counted, since they belonged to the second generation: those above thirty-five should be excluded, because when the first generation was completed, they had already reached the age of thirty-two; therefore, according to our calculation, they must at that time have had children who would belong to the first generation; they could not then belong to it themselves. Now we may suppose that, amongst the followers of Jacob, there were at least sixty males of various ages between these two extremes. This estimate will appear moderate indeed, when we remember that Abraham had been able to lead forth an army of 318 _trained servants, born in his house_ (_Gen._, xiv. 14). It will not be unreasonable to compute the accession of extra servants and proselytes at 15. If to these 75 we add 50 as the number of males within the prescribed limits, in Jacob’s own family, we shall have attained our estimated figure, 125. Lastly, our readers will find little difficulty in admitting an average of four sons in each family. From these data we obtain the following results: