One of the court records above referred to gives the details of a suit brought by the brothers Dritzehn against Gutenberg, in connection with this first manufacturing business. Another Dritzehn, a brother or a cousin of the above, had as early as 1437 applied to Gutenberg to be instructed (in consideration of the payment of an honorarium) in a “certain art” (_in etlicher kunst_). Shortly thereafter Gutenberg entered into an arrangement with a certain Hans Riffe of Lichtenau, and instructed him in the trade of manufacturing mirrors, Riffe making an investment in the business and sharing the profits. Dritzehn made in all, three contracts with Gutenberg; under the first, he was instructed in the art of stone-polishing, and took some interest in this branch of Gutenberg’s business; under the second, he interested himself in the manufacturing of mirrors; while the third contract refers to certain arts and undertakings (_kunste und afentur_) in which Dritzehn also received instruction, and to the carrying on of which he also contributed an investment. It is the opinion of some of the students on the subject that the researches of Gutenberg, which resulted in 1450 in the production of a working printing-press, had begun at least ten years back, and that, in connection with these researches, he had been obliged to borrow money or to accept investments from Dritzehn and from other associates. The vague terms used in referring to the undertakings which were associated with or which followed the mirror manufacturing business (“a certain art”) indicate that these associates had been cautioned to give no information as to the precise nature of the work in which Gutenberg was experimenting. Humphreys is of opinion that the term “manufacture of looking-glasses” was used partly as a blind and partly as a joke, and that Gutenberg was actually engaged in the production (with the aid of one of Koster’s assistants) of copies of the _Speculum_ (Mirror). Against this view is the fact that Gutenberg did not print the _Speculum_ at all. If Gutenberg were already working over the printing-press invention at the time of his association with Dritzehn and with Riffe, there may be some justice in the claim of Strasburg to be the birthplace of the printing-press. The completed press, however, was not produced until Gutenberg had returned to the old home city of the family--Mayence. After the close of the suit brought by Dritzehn against Gutenberg, that is to say, after 1440, there are no further references to Gutenberg’s undertakings in Strasburg. It is not even known whether or not he continued business operations there, but it appears that he was dwelling there as late as 1444. In 1448, he is recorded as again a citizen of Mayence, and it was in Mayence that, in 1450, the completed invention became known to the world.