The only hope of salvation for the Greek empire, and the adjacent kingdoms, would have been some more powerful weapon, some discovery in the art of war, that would give them a decisive superiority over their Turkish foes. Such a weapon was in their hands; such a discovery had been made in the critical moment of their fate. The chemists of China or Europe had found, by casual or elaborate experiments, that a mixture of saltpetre, sulphur, and charcoal, produces, with a spark of fire, a tremendous explosion. It was soon observed, that if the expansive force were compressed in a strong tube, a ball of stone or iron might be expelled with irresistible and destructive velocity. The precise Êra of the invention and application of gunpowder [91] is involved in doubtful traditions and equivocal language; yet we may clearly discern, that it was known before the middle of the fourteenth century; and that before the end of the same, the use of artillery in battles and sieges, by sea and land, was familiar to the states of Germany, Italy, Spain, France, and England. [92] The priority of nations is of small account; none could derive any exclusive benefit from their previous or superior knowledge; and in the common improvement, they stood on the same level of relative power and military science. Nor was it possible to circumscribe the secret within the pale of the church; it was disclosed to the Turks by the treachery of apostates and the selfish policy of rivals; and the sultans had sense to adopt, and wealth to reward, the talents of a Christian engineer. The Genoese, who transported Amurath into Europe, must be accused as his preceptors; and it was probably by their hands that his cannon was cast and directed at the siege of Constantinople. [93] The first attempt was indeed unsuccessful; but in the general warfare of the age, the advantage was on _their_ side, who were most commonly the assailants: for a while the proportion of the attack and defence was suspended; and this thundering artillery was pointed against the walls and towers which had been erected only to resist the less potent engines of antiquity. By the Venetians, the use of gunpowder was communicated without reproach to the sultans of Egypt and Persia, their allies against the Ottoman power; the secret was soon propagated to the extremities of Asia; and the advantage of the European was confined to his easy victories over the savages of the new world. If we contrast the rapid progress of this mischievous discovery with the slow and laborious advances of reason, science, and the arts of peace, a philosopher, according to his temper, will laugh or weep at the folly of mankind. [Footnote 91: The first and second volumes of Dr. Watson's Chemical Essays contain two valuable discourses on the discovery and composition of gunpowder.]