There is every reason to believe--indeed it seems clear that the Romans knew of gunpowder, though they only used it for purposes of fireworks; while the secret of the destructive Greek fire has been lost altogether. When gunpowder came to be used for purposes of war, invention busied itself upon instruments of destruction. When recently examining the Museum of the Arsenal at Venice, we were surprised to find numerous weapons of the fifteenth and sixteenth centuries embodying the most recent English improvements in arms, such as revolving pistols, rifled muskets, and breech-loading cannon. The latter, embodying Sir William Armstrong's modern idea, though in a rude form, had been fished up from the bottom of the Adriatic, where the ship armed with them had been sunk hundreds of years ago. Even Perkins's steam-gun was an old invention revived by Leonardo da Vinci and by him attributed to Archimedes.[8] The Congreve rocket is said to have an Eastern origin, Sir William Congreve having observed its destructive effects when employed by the forces under Tippoo Saib in the Mahratta war, on which he adopted and improved the missile, and brought out the invention as his own. Coal-gas was regularly used by the Chinese for lighting purposes long before it was known amongst us. Hydropathy was generally practised by the Romans, who established baths wherever they went. Even chloroform is no new thing. The use of ether as an anaesthetic was known to Albertus Magnus, who flourished in the thirteenth century; and in his works he gives a recipe for its preparation. In 1681 Denis Papin published his Traite des Operations sans Douleur, showing that he had discovered methods of deadening pain. But the use of anaesthetics is much older than Albertus Magnus or Papin; for the ancients had their nepenthe and mandragora; the Chinese their mayo, and the Egyptians their hachisch (both preparations of Cannabis Indica), the effects of which in a great measure resemble those of chloroform. What is perhaps still more surprising is the circumstance that one of the most elegant of recent inventions, that of sun-painting by the daguerreotype, was in the fifteenth century known to Leonardo da Vinci,[9] whose skill as an architect and engraver, and whose accomplishments as a chemist and natural philosopher, have been almost entirely overshadowed by his genius as a painter.[10] The idea, thus early born, lay in oblivion until 1760, when the daguerreotype was again clearly indicated in a book published in Paris, written by a certain Tiphanie de la Roche, under the anagrammatic title of Giphantie. Still later, at the beginning of the present century, we find Thomas Wedgwood, Sir Humphry Davy, and James Watt, making experiments on the action of light upon nitrate of silver; and only within the last few months a silvered copper-plate has been found amongst the old household lumber of Matthew Boulton (Watt's partner), having on it a representation of the old