55. CONVENTIONAL DIAGRAM OF A WATER SOFTENING PLANT 216 56. AN "ENCLOSED" STEAM ENGINE 220 57. AN ELECTRICALLY DRIVEN PAPER MACHINE 222 58. DIAGRAM OF THE "EIBEL" PROCESS 223 THE MANUFACTURE OF PAPER CHAPTER I HISTORICAL NOTICE _History._--The art of paper-making is undoubtedly one of the most important industries of the present day. The study of its development from the early bygone ages when men were compelled to find some means for recording important events and transactions is both interesting and instructive, so that a short summary of the known facts relating to the history of paper may well serve as an introduction to an account of the manufacture and use of this indispensable article. _Tradition._--The early races of mankind contented themselves with keeping alive the memory of great achievements by means of tradition. Valiant deeds were further commemorated by the planting of trees, the setting up of heaps of stones, and the erection of clumsy monuments. _Stone Obelisks._--The possibility of obtaining greater accuracy by carving the rude hieroglyphics of men and animals, birds and plants, soon suggested itself as an obvious improvement; and as early as B.C. 4000 the first records which conveyed any meaning to later ages were faithfully inscribed, and for the most part consigned to the care of the priests. _Clay Tablets._--The ordinary transactions of daily life, the writings of literary and scientific men, and all that was worthy of note in the history of such nations as Chaldea and Assyria have come down to us also, inscribed on clay tablets, which were rendered durable by careful baking. On a tablet of clay, one of the earliest specimens of writing in existence, now preserved in the British Museum, is recorded a proposal of marriage, written about B.C. 1530, from one of the Pharaohs, asking for the hand of the daughter of a Babylonian king. _Waxed Boards._--Bone, ivory, plates of metal, lead, gold, and brass, were freely used, and at an early period wooden boards covered with wax were devised by the Romans. In fact, any material having a soft impressionable surface was speedily adopted as a medium for the permanent expression of men's fancy, so that it is not strange to find instances of documents written on such curious substances as animal skins, hides, dried intestines, and leather. The works of Homer, preserved in one of the Egyptian libraries in the days of Ptolemæus Philadelphus, were said to have been written in letters of gold on the skins of serpents. _Leaves, Bark._--The first actual advance in the direction of paper, as commonly understood, was made when the leaves and bark of trees were utilised. The latter especially came speedily into favour, and the extensive use of the inner bark (_liber_) made rapid headway. Manuscripts and documents written on this liber are to be found in many museums.