It is a well-known fact to Bibliographers that the same blocks were sometimes used by different printers in two places quite far apart, and at various intervals during the seventeenth and eighteenth centuries. That the same blocks were employed is apparent from a comparison of technical defects of impressions taken at different places, and at two periods. There was no method of duplication in existence until stereotyping was first invented in 1725; even then the details were somewhat crude, and the process being new, it met with much opposition and was practically not adopted until the early part of the nineteenth century. Electrotyping, which is the ideal method of reproducing woodblocks, was not introduced until 1836 or thereabouts. Of course, it was quite possible to re-engrave the same design, but absolute fidelity could not be relied on by these means, even if executed by the same hand. The earliest date which appears on a book in which the head-piece, containing the device of the light A and dark A is found, is 1563. The book is "De Furtivis Literarum Notis Vulgo. De Ziferis," Ioan. Baptista Porta Neapolitano Authore. Cum Privilegio Neapoli, apud Ioa. Mariam Scotum. MDLXIII. (Figure VIII.) It is only used once--over the dedication Ioanni Soto Philippi Regis. There is no other head-piece in the book. John Baptist Porta was, with the exception of Trithemius, whom he quotes, the first writer on cyphers. At the time at which he wrote cypher-writing was studied in every Court in Europe. It is significant that this emblematic device is used in the earliest period in which head-pieces were adopted, in a book which is descriptive and is in fact a text-book of the art of concealment. This has, however, now been proved to be a falsely dated book. The first edition of this work was published in Naples in 1563 by Ioa. Marius Scotus, but this does not contain the A A design. In 1591 the book was published in London by John Wolfe; this reprint was dedicated to Henry Percy, Earl of Northumberland. After the edition had been printed off, the title-page was altered to correspond with the 1563 Naples publication. The dedication was taken out, and a reprint of the original dedication was substituted, and over this was placed the A A head-piece; then an edition was struck off, and, until to-day, it has been sold and re-sold as the first edition of Baptista Porta's work. It is difficult to offer any explanation as to why this fraud was committed.