The crayon method in combination with one or two tint plates is the method that is easiest for the artist to handle. Now this method is very difficult to print, demanding great practice if good, strong, and clear impressions are to be produced. Since there are as yet no complete printeries where an artist can have his own plates printed without danger of damage, there is nothing left except to print them himself, which causes many imperfect impressions that must be destroyed for the credit of the artist. Herr Kunike had this experience; but he took his imperfect impressions, when they were not entirely spoiled, and worked them over with black crayon. It developed that twelve impressions could be so well touched up by hand that they would fittingly pass as originals, in the time which would be required to copy a single picture properly. As this treatment of illustrations produces their value only by merit of the final finishing, they may be considered as being the same as copies that are made by an artist of his own work, wherein it happens often that the copy turns out better than the original. Just as I was preparing to leave Vienna I received several numbers of the _Anzeiger für Kunst und Gewerbfleiss_, in which Herr Direktor von Schlichtegroll, General Secretary of the Royal Bavarian Academy of Sciences, had inserted several letters suggesting an inquiry into the invention of lithography. He had used the information obtained from my brothers and from other inhabitants of Munich. On my arrival there I visited him at once to thank him for his patriotic endeavors, and to make some corrections of the story told by him. I had the fortune to win him as a steady friend, who became continually interested in giving my work a greater field. The completion of this text-book is due to his steadfast encouragement. He furnished me with the opportunity to meet many worthy men and also to demonstrate my many improvements before the Royal Academy of Sciences, the Polytechnical Union, and at last even before their majesties, our most gracious King and his most highly venerated spouse, that illustrious connoisseur and protectress of the arts. Never to be forgotten by me will be the moment when the gracious applause of the royal pair rewarded me for all the exertions of my life. Oh! If only human life were not so limited, if it were granted to me to execute only one tenth part of my designs, I would make myself worthy of this great honor by making many another useful invention! But the time passes swiftly during our helpless wishing and striving; and when twenty or thirty years have been lived, there remains for us only amazement at beholding how little has been done of all that which glowing imagination and fiery energy painted as being so easy to carry out.