We are not here directly concerned with his political career, in his checking of governors and proprietaries, in his activities as the greatest of American diplomats, as the signer of the Declaration of Independence, of the Treaty of Versailles, and of the American Constitution, nor as the president of the Supreme Executive Council of Pennsylvania in his eightieth, eighty-first, and eighty-second years. When he was eighty-four, as president of the Society for Promoting the Abolition of Slavery, he signed a petition to Congress against that atrocious debasement of human nature, and six weeks later, within a few weeks of his death, defended the petition with his accustomed vigor, humor, wisdom, and ardent love of liberty. Turgot wittily summed up Franklin's career by saying that he had snatched the lightning from the heavens and the scepter from the hands of tyrants (_eripuit cœlo fulmen sceptrumque tyrannis_); for both his political and scientific activities sprang from the same impelling emotion--hatred of the exercise of arbitrary power and desire for human welfare. It is no wonder that the French National Assembly, promulgators of the Rights of Man, paused in their labors to pay homage to the simple citizen, who, representing America in Paris from his seventy-first till his eightieth year, had by his wisdom and urbanity illustrated the best fruits of an instructed democracy. REFERENCES American Philosophical Society, _Record of the Celebration of the Two Hundredth Anniversary of the Birth of Benjamin Franklin_. S. G. Fisher, _The True Benjamin Franklin_. Paul L. Ford, _Many-sided Franklin_. Benjamin Franklin, _Complete Works_, edited by A. H. Smyth, ten volumes, vol. X containing biography. FOOTNOTES: [2] See _The Advice of W. P. to Mr. Samuel Hartlib for the Advancement of some Particular Parts of Learning_, in which is advocated a _Gymnasium Mechanicum_ or a _College of Tradesmen_ with fellowships for experts. Petty wanted trade encyclopedias prepared, and hoped for inventions in abundance. CHAPTER X THE INTERACTION OF THE SCIENCES--WERNER, HUTTON, BLACK, HALL, WILLIAM SMITH The view expressed by Franklin regarding the existence of a fiery mass underlying the crust of the earth was not in his time universally accepted. In fact, it was a question very vigorously disputed what part the internal or volcanic fire played in the formation and modification of rock masses. Divergent views were represented by men who had come to the study of geology with varying aims and diverse scientific schooling, and the advance of the science of the earth's crust was owing in no small measure to the interaction of the different sciences which the exponents of the various points of view brought to bear.