=Hollar.=--Wenceslaus Hollar was a Bohemian by birth, and came to England under the patronage of the Duke of Arundel in 1637. During a lifetime of peculiar misfortunes and vicissitudes, he etched something like 2700 plates. As an ardent Royalist, he was drawn into the civil war of 1643-44. He also passed through the Great Plague and the Fire of London. Difficulties and hardships ever beset his path, yet his industry and fond attachment to art never flagged. The very fact that ever-recurring misfortunes and privations never impaired his power as a most remarkable and ingenious illustrator is ample proof, if such be required, of his genius. Hollar's etchings are distinguished by an intense fidelity. They abound in historical interest of a reliable and fascinating kind, and though never showy they possess a wealth of artistic beauty and artistic expression. It is difficult to understand how an artist with Hollar's gigantic, productive energy should end his days in abject poverty. Mezzotint engraving is the art of engraving on metal _in tones_. It dates back to about the middle of the seventeenth century. Its history is interesting if only for the fact that it has been developed chiefly in this country, the high degree of perfection to which it attained being chiefly due to English artists. So much so, indeed, that it has frequently been referred to as _la manaire Anglais_. =Invention.=--The invention of Mezzotint engraving was the result of an every-day circumstance which attracted the attention of a soldier more thoughtful than his fellows. Ludwig von Sigen was a lieutenant-colonel in the army of the Landgrave of Hesse Cassel when he observed the corrosive action of moisture on the stock of a musket. The metal work had been ornamented with an engraved design, and the ground formed by corrosion in conjunction with the engraved lines suggested an idea from which von Sigen subsequently developed the mezzotint process. This story of von Sigen's discovery is regarded by some authorities with a suspicion of doubt, and a suggestion is made that his purpose was to invest this introduction of a new reproductive art with a romantic as well as an artistic interest. In any case, the gallant colonel's credit is maintained, and it is interesting to note that the principle of his invention remains still unchanged. The chief purpose of later developments was to facilitate the production of a perfectly even ground. On the presentation of his first print to the Landgrave of Hesse, von Sigen declared, "There is not a single engraver, or a single artist, who knows how this work is done." About twelve years afterwards the inventor divulged his secret to Prince Rupert, by whom it was brought to England. It is generally supposed that Prince Rupert carefully preserved the secret of this new process for some time, and then in a generous mood he imparted it to Vallerant Valliant, who fortunately for English art made his knowledge widespread.