Nevertheless, with that quiet pertinacity which was one of his conspicuous traits, he still kept the theme in mind, and let it be known to his friends in Paris and London, as well as in Madrid and elsewhere, that all materials bearing upon the career of Philip II. were much desired by him. These friends responded very zealously to his wishes. In Paris, M. Mignet and M. Ternaux-Compans allowed Dr. Lembke to have their important manuscript collections copied. In London, Prescott's correspondent and former reviewer, Don Pascual de Gayangos, searched the documents in the British Museum and a very rich private collection owned by Sir Thomas Philips. He also visited Brussels, where he found more valuable material, and later, having been appointed Professor of Arabic in the University of Madrid (1842), he used his influence on behalf of Prescott with very great success. Many noble houses in Spain put at his disposal their family memorials. The National Library and other public institutions offered whatever they possessed in the way of books and papers. Two years later, this indefatigable friend spent some weeks at Simancas, where he unearthed many an interesting _trouvaille_. Even these sources, however, were not the only ones which contributed to Prescott's store of documents. Ferdinand Wolf in Vienna, and Humboldt and Ranke in Berlin, also aided him, and secured additional material, not only in Austria and Prussia, but in Tuscany. His collection grew apace; so that, long before he was ready to take up the subject of Philip II., he possessed over three hundred and seventy volumes bearing directly upon the reign of that monarch, while his manuscript copies, which he caused to be richly bound, came to number in the end some thirty-eight huge folios. These occupied a position of special honour in his library, and were playfully called by him his Seraglio.