Papyrus was made by cutting the stalk of the reed lengthwise into very thin strips. These strips were laid side by side on a board until the desired width was obtained. Another layer of shorter strips was then laid across the long ones entirely covering them. This mat, or "net" as it was technically called, was then soaked in the water of the Nile. Whether there was any particular virtue in the Nile water, which is always more or less charged with mud, or the desired result was obtained simply by the action of water on the reed itself, is not clear. After the soaking was completed, the "net" was dried in the sun, hammered to expel air and water, polished by rubbing with some hard smooth substance, and probably sized, although it is possible that all the sizing necessary was provided by the sap of the reed itself. The sheets were then trimmed even and joined by the edges into a long strip, usually of about twenty sheets. This was rolled on a stick and was then ready for sale as writing material. The quality of the papyrus varied according to the part of the reed from which the strips were cut, and it was the commercial custom to put sheets of varying quality into the same strip or roll. The best sheets were put on the end which would come on the outside of the roll, grading down to the worst at the other end. This was done for two reasons: first, in order that the best material should come where it would receive the most wear, and secondly in order that in case the roll was not entirely used the waste part should be of inferior quality. Papyrus continued to be used as the general writing material of the civilized world until about the time of Christ, and held its place for certain purposes until the 11th century, at which period we find it still used for Papal Bulls and other important documents. It was revived in Egypt by the Copts, as the people of Egypt were then called, in the 7th century and was used by them extensively until the middle of the 13th. [Illustration: Parchment-roll, or volumen. (Our word volume comes from volumen.)]