People wrote on stone, on metals, on the bark and leaves of many kinds of trees, on dried or baked clay, on wood, on ivory, wax, linen, the hides of quadrupeds, on parchment, the best of these preparations; on papyrus, which is the inner bark of a reed growing in the Nile; then on paper made of cotton; and lastly, on paper made from hemp and flax, called rag paper. The Roman world had adopted the use of papyrus, which was a very important branch of commerce at Alexandria. We find proof of this in the writers of antiquity: St. Jerome bears witness to it as far as regards the fifth century of our era. The Latin and Greek emperors gave their diplomas on papyrus. Popes traced their most ancient bulls upon it. The charters of the kings of France of the first race were also issued on papyrus. From the eighth century parchment contended with papyrus; a little later cotton paper also became its competitor, and the eleventh century is generally fixed on as the period when papyrus was entirely superseded by the new materials appropriated to the preservation of writing. For writing on papyrus the brush or reed was employed, with inks of different colours; black ink was, however, most generally used. There grew on the banks of the Nile, at the time when the reed furnished papyrus, another sort of reed, stiffer and also more flexible, and admirably suited for the manufacture of the _calamus_, an instrument supplying the place of the pen, which was not adopted before the eighth century. The size of manuscripts was in no way subject to fixed rules, there were volumes of all dimensions; the most ancient on parchment are, in general, longer than they are broad, or else are square; the writing rests on a line traced with the dry point of the _calamus_, and afterwards with black-lead; the parts making up a volume are composed of an indeterminate number of leaves; a word or a figure, placed at the bottom of the last page of each part and at the end of the volume, serves as a _catchword_ from one fasciculus to another. The emperors of Constantinople used to sign in red ink the acts of their sovereignty; their first secretary was the guardian of the vase containing the cinnabar (vermilion), which the emperor alone might use. Some diplomas of the kings of France of the second race are signed in the same manner. In valuable manuscripts, great use was made of golden ink, especially when the parchment was dyed purple; but red ink was almost always employed for capital letters or for the titles of books, and for a long time after the invention of printing the volumes still had the _rubrics_ (_ruber_, red) painted or beautifully executed with the pen.