"Gutenburg, Johannes or Henne, also called Gensfleisch, claimed by the Germans to have been the inventor of the art of printing with movable types, born at Mainz; for some time lived in Strasburg as a polisher of precious stones, mirrors, &c.; he set up his first printing-press at Mainz about 1450 (1400-1468)" -The Nuttall Encyclopædia. 1907.
.GUTENBERG, JOHANN (c. 1398-1468), German printer, is supposed to have been born c. 1398-1399 at Mainz of well-to-do parents, his father being Friele zum Gensfleisch and his mother Elsgen Wyrich (or, from her birthplace, zu Gutenberg, the name he adopted). He is assumed to be mentioned under the name of “Henchen” in a copy of a document of 1420, and again in a document of c. 1427-1428, but it is not stated where he then resided. On January 16, 1430, his mother arranged with the city of Mainz about an annuity belonging to him; but when, in the same year, some families who had been expelled a few years before were permitted to return to Mainz, Gutenberg appears not to have availed himself of the privilege, as he is described in the act of reconciliation (dated March 28) as “not being in Mainz.” It is therefore assumed that the family had taken refuge in Strassburg, where Gutenberg was residing later. There he is said to have been in 1434, and to have seized and imprisoned the town clerk of Mainz for a debt due to him by the corporation of that city, releasing him, however, at the representations of the mayor and councillors of Strassburg, and relinquishing at the same time all claims to the money (310 Rhenish guilders = about 2400 mark). Between 1436 and 1439 certain documents represent him as having been engaged there in some experiments requiring money, with Andreas Dritzehn, a fellow-citizen, who became not only security for him but his partner to carry out Gutenberg's plan for polishing stones and the manufacture of looking-glasses, for which a lucrative sale was expected at the approaching pilgrimage of 1440 (subsequently postponed, according to the documents, although there is no evidence for this postponement) to Aix-la-Chapelle. Money was lent for this purpose by two other friends. In 1438 another partnership was arranged between Gutenberg, Andreas Dritzehn, and Andreas and Anton Heilmann, and that this had in view the art of printing has been inferred from the word “drucken” used by one of the witnesses in the law proceedings which soon after followed. An action was brought, after the death of Dritzehn, by his two brothers to force Gutenberg to accept them as partners in their brother's place, but the decision was in favour of the latter. In 1441 Gutenberg became surety to the St Thomas Chapter at Strassburg for Johann Karle, who borrowed 100 guilders (about £16) from the chapter, and on November 17, 1442, he himself borrowed 80 livres through Martin Brechter (or Brehter) from the same chapter. Of his whereabouts from the 12th of March 1444 (when he paid a tax at Strassburg) to the 17th of October 1448 nothing certain is known. But on the latter date we find him at Mainz, borrowing 150 gold guilders of his kinsman, Arnold Gelthus, against an annual interest of 7½ gold guilders. We do not know whether the interest on this debt has ever been paid, but the debt itself appears never to have been paid off, as the contract of this loan was renewed (vidimused) on August 23, 1503, for other parties. It is supposed that soon afterwards Gutenberg must have been able to show some convincing results of his work, for it appears that about 1450 Johann Fust (q.v.) advanced him 800 guilders to promote it, on no security except that of “tools” still to be made. Fust seems also to have undertaken to advance him 300 guilders a year for expenses, wages, house-rent, parchment, paper, ink, &c., but he does not appear to have ever done so. If at any time they disagreed, Gutenberg was to return the 800 guilders, and the “tools” were to cease to be security. It is not known to what purpose Gutenberg devoted the money advanced to him. In the minutes of the law-suit of 1455 he himself says that he had to make his “tools” with it. But he is presumed to have begun a large folio Latin Bible, and to have printed during its progress some smaller books and likewise the Letter of Indulgence (granted on the 12th of April 1451 by Pope Nicholas V. in aid of John II., king of Cyprus, against the Turks), of 31 lines, having the earliest printed date 1454, of which several copies are preserved in various European libraries. A copy of the 1455 issue of the same Indulgence is in the Rylands Library at Manchester (from the Althorp Library).-Encyclopædia Britannica (11th ed.). 1911.
Gutenberg (gōō′ten-bĕrg), Johannes, the inventor of printing with movable type, was born about 1400 in Mainz (Mayence), Germany. His proper name was Gensfleisch or Gansfleisch, which means Goose flesh. In 1434 he lived in Strassburg, teaching stonecutting, mirror-polishing and other similar arts. Between 1444 and 1448 he returned to Mainz, where, in 1449 or 1450, he entered into a partnership with Johannes Faust, who furnished the money to set up a printing-press. This partnership was dissolved in 1455 by Faust bringing a suit against Gutenberg to recover money advanced, and Faust gained control of the press. Gutenberg however, assisted by Dr. Homery, set up another press, at which he wrought until his death in 1468. A bronze monument, the work of Thorwaldsen, has been erected to his memory at Mainz. There are a few copies preserved of books printed by him, which bring enormous prices. See Memoirs of Celebrated Characters by Lamartine.-The New Student's Reference Work. 1914.
So this seems to prove that he knew how to make metal mirrors and there was a financial venture regarding them around 1440 that flopped. Nothing about periscopes....yet.
Next up to the library and ILL, to get my next resource.