It is plain, as we note the nature of the land through which the great river flows, that no rich soil would be accumulated from the banks it washes in its downward course. We must look to the high tablelands where the two large tributaries, the Blue Nile and the Atbara, have their beginnings, to find the mountain loam that has given the valley a fertile soil, thirty feet in depth, and has built up the grain-producing delta, one hundred miles in length and more in breadth. Again and again we are forced to remember that Egypt is indeed the gift of the Nile.
Yearly Rise of the Nile.
This brings us back once more to the subject of the inundations. Early in June the Nile begins to rise below the first cataract. In July it has become swollen throughout its course.
The highest water mark is reached about September fifteenth. By the first of November the river begins to recede and is at low water again by the last of January, although it continues to diminish until the following June.
Nilometers are used to register the river's rise. These are wells in which the water can fluctuate freely, with a stone column in the center marked as a scale. The ell is the unit of measure, being equal to about twenty-one and one-third inches. At low water the river registers about seven ells. If during the inundation sixteen ells are reached, all Egypt is supplied with water and fine crops are assured throughout the land.
Nilometers.
From earliest times the rise of the Nile was closely watched, and nilometers, which were under the special protection of the State, constructed. Today these water gauges are under the inspection of government officials. Taxes have always been apportioned according to the amount of the inundation, and it has been to the interest of the government, naturally, that these be as heavy as possible. For this reason it has often been claimed, both in ancient and modern times, that the official report of the high water mark greatly exceeded the actual rise.
There is no rainfall in the valley and little in the delta, so whatever moisture Egypt receives must come from the Nile. The entire valley is not of equal elevation but becomes higher as it spreads out on either side, and so a vast system of irrigation must be maintained to make good crops possible. Large sums have been expended in the construction of dams, embankments and canals to contain the water after the river recedes, allowing the amount thus retained to be drawn off as it is needed. From canals it is drawn off into trenches for still higher land, and artificial means of various kinds have always been employed to lift the water from one level to another. It is estimated that tens of thousands of men and boys are constantly engaged in this elevation of water from one level to another, in order that farms throughout the valley may receive the necessary moisture and fertility. As rapidly as one crop is harvested, the soil is made ready for another, so that as many as five crops are frequently harvested in a year on a given acreage.
Influence of Topography.
With a sea on the north, mountains on the east, cataracts to the south and a desert on the west, what would be the natural effect upon the inhabitants of physical conditions such as these prevailing in the land of Egypt? They determined that the Egyptians would be left to develop their civilization unmolested for the most part by outside influences. Such physical features account for the fact that for hundreds of years that was a land, not of war, but of peace. Think for a moment what natural boundaries have meant to nations of Europe. England's isolation has been largely due to her stormy channel, while the independence of the Swiss is accounted for by their inaccessible mountain home. Austria, on the other hand, has known the disastrous effects of repeated invasions, while Poland has lost her identity and has been appropriated by her neighbors because of unfortunate situation and the lack of natural defenses.