This simple and ingenious process has been carried to such perfection, that the most beautiful artistic effects can be produced by it far more economically than by any other style of engraving; and further improvements in the art are being continually made. It is satisfactory, therefore, to be able to trace its history from its very beginnings, of which an interesting account has been published by the inventor himself. M. Senefelder's father was an actor at Munich, and in his youth he followed the same profession. He turned his attention afterwards to music; and it was in his attempts to devise some means of printing his compositions economically that he chanced to discover the art of Lithography. He had previously made himself acquainted with the methods of copper-plate printing, and he commenced his operations by etching the notes of music on copper-plates, covered with varnish in the ordinary way. He found, however, that it would require much practice to enable him to do this properly, and not being able to buy copper-plates for his rude essays, he thought of practising upon stones. Fortunately for the success of his efforts, the quarries at Solenhofen, near Munich, supplied him with slabs of stone admirably adapted for the purpose; and it is a remarkable coincidence, that the material which Senefelder used for his experiments is the best for the purpose of Lithography that has hitherto been discovered. His chief object in making use of these slabs of stone was to practise himself in the manipulation of writing the notes, and of biting them in with _aqua-fortis_ (nitric acid), as he supposed the slabs would be too brittle to bear the action of the press. He did not try, therefore, to have these etchings on stone proved by the press, but he contented himself with holding them up to a mirror to observe the progress he was making in writing backwards. Having at length been supplied with much thicker slabs of stone, to bear the requisite pressure, he endeavoured to grind and polish them sufficiently for the purpose of being printed from, in the same manner as copper-plates. He succeeded to some extent in doing so, by means of diluted nitric acid; and he contrived to obtain about fifty good impressions from the stone. In all these attempts at Lithography, the lines were etched into the stone by the action of nitric acid, and the only advantages professed to be gained by the process were the questionable ones of comparative cheapness of material, and greater facility of working. M. Senefelder admits that there was nothing new in engraving upon stone; all that he claims in that part of the invention is, the manner of polishing the surface, and the composition of the ink adapted for printing from it. The most important step in the progress of the invention of Lithography, as at present practised, was made by accident, which he thus describes:--