“Franklin,” writes one of his biographers, “cannot be ranked among the great men of science, the Newtons, the Keplers, or the Humboldts, Huxleys or Darwins. He belongs, rather, in the second class, among the minor discoverers. But his discovery of the nature of lightning was so striking and so capable of arousing the wonder of the masses of mankind and his invention of the lightning rod was regarded as so valuable that he has received more popular applause than men whose achievements were greater and more important. His command of language had seldom been put to better use than in explaining the rather subtle ideas and conceptions in the early development of electricity. Even now, after the lapse of one hundred and fifty years, we seem to gain a fresher understanding of that subject by reading his homely and beautiful explanations; and modern students would have an easier time if Franklin were still here to write their text-books.” Public business and long years of diplomatic service interrupted the original study of science to a great extent; but even so, in England, in France, and in the closing years of his life in Philadelphia, Franklin found time, now and then, to devote to that loving investigation of Nature, which, after his thirtieth year, became the great passion of his life. Everything in the way of scientific research fascinated him: he investigated earthquakes, eclipses, storms, winds, the science of sound, the laws of hot air and its movements, ventilation, water-spouts, phosphorescence (“light in sea-water,” he called it), the cause of saltiness in the sea, the Gulf Stream, rainfall, evaporation, the aurora borealis, light, heat, the daily motion of the earth, and many other subjects. He studied music as a science, and invented a new kind of musical glasses (fashionable at that time) called “Armonica.” He studied political economy in a scientific way, and was so interested in agriculture that he tried experiments on his New Jersey farm. He also invented the “Pennsylvania fireplace” and the “Franklin” stove. Though his scientific writings are numerous, they are in the form of essays and letters. His investigations and experiments were thus made known to the world in letters to friends in France and England; for, as there were no scientific periodicals in those days, men of learning kept up a lively correspondence and occasionally issued a pamphlet. PREPARED BY THE EDITORIAL STAFF OF THE MENTOR ASSOCIATION ILLUSTRATION FOR THE MENTOR. VOL. 6. No. 7. SERIAL No. 155 COPYRIGHT, 1918, BY THE MENTOR ASSOCIATION, INC. [Illustration: FROM THE ORIGINAL PAINTING BY CHAPPEL DRAFTING THE DECLARATION OF INDEPENDENCE--FRANKLIN, JEFFERSON, ADAMS, LIVINGSTON, SHERMAN] _BENJAMIN FRANKLIN_ _As Man of Letters_ FIVE