The origin, of course, of the astounding error by which "the great master of military architecture" misdated this keep by nearly a century,[993] and took an essentially late work for one of the earliest in existence, was the same fatal delusion that _castrum_ or _castellum_ meant precisely what it did not mean, namely, a tower. "Castellum novum super flumen Tyne condidit" is the expression applied to Robert's work in 1080, and the absence of a "tower" explains the fact that Fantosme makes no mention of a "tur" when describing "Le Noef Chasteau sur Tyne," the existing keep not being available at the time of which he wrote. * * * * * We now come to our last case, that of the Château d'Arques. "Arques," writes Mr. Clark, "is one of the earliest examples of a Norman castle."[994] It is, Mr. Freeman holds, "a fortress which is undoubtedly one of the earliest and most important in the history of Norman military architecture."[995] No apology, therefore, is needed for discussing the date of this celebrated structure, so long a subject of interest and of study both to English and to French archæologists. As at Colchester and in other places, the very wildest theories have been generally advanced, and archæologists have only gradually sobered down till they have virtually agreed upon a date for this keep which is actually, I venture to think, less than a century wrong. In his noble monograph upon the fortress, the basis of all subsequent accounts,[996] M. Deville enumerates, with contemptuous amusement (pp. 49, 268-272), the rival theories that it was built (1) by the Romans; (2) by "Clotaire I." in 553—the date 1553 on one of the additions for the structure having actually been so read; (3) by "Charles Martel" in 745, 747, or 749 (on the strength of another reading of the same date, confirmed by a carving of his coat-of-arms)—these being the dates given by Houard and Toussaint-Duplessis. At the time when Deville himself wrote the study of castles was still in its infancy, and of the two sources of evidence now open to us, the internal (that of the structure itself) and the external (that of chronicles and records), the latter alone was ripe for use. Now, at Arques, precisely as at our own Rochester, the written evidence has hitherto appeared conflicting to archæologists, but only because the language employed has never yet been rightly understood. On the one hand we read in William of Jumièges, an excellent authority in the matter, that "Hic Willelmus [the Conqueror's uncle] castrum Archarum in cacumine ipsius montis condidit;" and in the _Chronicle of Fontenelle_, that this same William "Arcas castrum in pago Tellau primus statuit;" also, in William of Poitiers, that "id munimentum ... ipse primus fundavit:" on the other, we read in Robert du Mont, a first-rate and contemporary authority, who may indeed be termed a specialist on the subject, that "Anno MCXXIII. castellum quod vocatur