There was an artificer in Rome, who made vessels of glass of so tenacious a temper, that they were as little liable to be broken as those that are made of gold and silver: when therefore he had made a vial of the purer sort, and such as he thought a present worthy of Caesar alone, he was admitted into the presence of their then Emperor Tiberius. The gift was praised, the skilful hand of the artist applauded, and the donation of the giver accepted. The artist, that he might enhance the wonder of the spectators, and promote himself yet further in the favour of the Emperor, desired the vial out of Csesar's hand, and threw it with such force against the floor, that the most solid metal would have received some damage or bruise thereby. Csesar was not only amazed, but affrighted with the act; but he, taking up the vial from the ground, (which was not broken, but only bruised together, as if the substance of the glass had put on the temperature of brass,/ he drew out an instrument from his bosom, and beat it out to its former figure. This done, he imagined that he had conquered the world, as believing that he had merited an acquaintance with Caesar, and raised the admiration of all the beholders; but it fell out otherwise, for the Emperor inquired if any other person besides himself was privy to the like tempering of glass? When he had told him, "No," he commanded his attendants to strike off his head, saying, "That should this artifice come once to be known, gold and silver would be of as little value as the dirt of the street." Long after this, viz. in 1610, we read, that amongst other rare presents, then sent from the Sophy of Persia to the king of Spain, were six mirrors of malleable glass, so ex-quisitely tempered that they could not be broken.