Franklin was forty-two years old at this time; and it is a singular fact that his career as a philosopher did not begin really until he had passed his fortieth birthday. But from the time he was released from the care of the printing office, his advancement in science was rapid. His fame spread abroad, both in this country and Europe, so that, in a few years, he became one of the most renowned philosophers in the world. In a former chapter we described his experiment with a kite, to prove that lightning and the electric fluid are identical; and this discovery established his fame as the greatest electrician of the world. The Royal Society of London elected him a member by a unanimous vote, and the next year bestowed upon him the Copley medal. Yale College conferred upon him the degree of Master of Arts; and Harvard University did the same. Suddenly Franklin found himself the most conspicuous character in American history--a philosopher of the most honored type. Mignet said of him, "Thus all at once distinguished, the Philadelphia sage became the object of universal regard, and was abundantly loaded with academic honors. The Academy of Sciences of Paris made him an associate member, as it had Newton and Leibnitz. All the learned bodies of Europe eagerly admitted him into their ranks. Kant, the celebrated German philosopher, called him 'the Prometheus of modern times.' To this scientific glory, which he might have extended if he had consecrated to his favorite pursuits his thoughts and his time, he added high political distinction. To this man, happy because he was intelligent, great because he had an active genius and a devoted heart, was accorded the rare felicity of serving his country, skilfully and usefully, for a period of fifty years; and after having taken rank among the immortal founders of the positive sciences, of enrolling himself among the generous liberators of the nations." A few years later, the three Universities of St. Andrew's, Oxford, and Edinburgh, conferred upon him the degree of Doctor of Laws. Europe vied with America in tributes of honor and praise. His electrical experiments made him the author of several useful inventions, among which the LIGHTNING ROD was the foremost. It came into general use, not only in our country, but also in Europe. The celebrated Kinnersley wrote to him, "May this method of security from the destructive violence of one of the most awful powers of Nature meet with such further success as to induce every good and grateful heart to bless God for the important discovery! May the benefit thereof be diffused over the whole globe! May it extend to the latest posterity of mankind, and make the name of Franklin, like that of Newton, IMMORTAL!"