The third language, however, remained unknown until the finishing stroke to its decipherment was given by the discovery by Layard under the great mound of Koyunjik near Mosul on the Tigris, the site of the ancient Nineveh, of the royal palace of Asshurbanipal, or Sardanapalus, the grandson of Sennacherib, and one of the greatest Assyrian monarchs, who lived about 650 B.C. This palace contained a royal library like that of Alexandria or the British Museum, the contents of which had been carefully collected from the oldest records of previous libraries and temples, and almost miraculously preserved. The secret of the preservation of these Assyrian and Chaldæan remains, is that the district contains no stone, and all the great buildings were constructed mainly of sun-dried bricks, and built on mounds or platforms of the same material to raise them above the alluvial plain. These, when the cities were deserted, crumbled rapidly under the action of the air and rains, which are torrential at certain seasons, into shapeless rubbish heaps of fine dry dust and sand, under which everything of more durable material was securely buried. So rapid was the process, that when Xenophon on the famous retreat of the ten thousand traversed the site of Nineveh only two hundred years after its destruction, he found nothing but the ruins of a deserted city, the very name and memory of which had been lost. As regards the contents of the library the explanation of their perfect preservation is equally simple. The books were written, not on perishable paper or parchment, but on cylinders of clay. It is evident that the cuneiform characters were exceedingly well adapted for this description of writing, and probably originated from the nature of the material. A fine tenacious clay cost nothing, was readily moulded into cylinders, and when slightly moist was easily engraved by a tool or style stamping on it those wedge-like characters, so that when hardened by a slow fire the book was practically indestructible. So much so, indeed, that though the palace, including the library with its shelves and upper stories, had all fallen to the ground, and the book-cylinders lay scattered on the floor, they were mostly in a state of perfect preservation. Other similar finds have been made since, notably one of another great library of the priestly college at Erech, founded or enlarged as far back as 2000 B.C. by Sargon II. Among the books thus preserved there are fortunately translations of old Accadian works into the more modern Aramaic or Assyrian, either interlined or in parallel columns, and, also grammars and dictionaries of the old language to assist in its study. It appears that as far back as 2000 years B.C. this old language had already become obsolete, and was preserved as Latin or Vedic Sanscrit are at the present day, as the venerable language for religious uses, in which the earliest sacred books, historical