Henry A. Rowland became at Johns Hopkins University in Baltimore one of the great physical investigators and inventors of the nineteenth century. As a boy he delighted in chemical experiments, glass-blowing, and similar occupations. The family were often summoned by the young enthusiast to listen to lectures which were fully illustrated by experiments, not always free from prospective danger. His first five-dollar bill bought him, to his delight, a galvanic battery. The sheets of the New York “Observer” he converted into a hot-air balloon, which made a brilliant ascent and flight, setting fire, at last, to the roof of a neighboring house. One day he saw a pump at work in the hold of a steamer, sending out a stream which fell from a height of five or six feet to the river. “Why,” he exclaimed, “don’t you put that pipe down into the river and save power?” As a student at the Troy Polytechnical Institute he invented a method of winding naked strips of wire on cloth so as virtually to effect its insulation. This was afterward profitably patented by some one else. In “The Senses and the Intellect” Professor Alexander Bain considers the inventing and discovering mind:-- The Passion for Experiment. “Not one of the leading mental peculiarities applicable to scientific constructiveness can be dispensed with in the constructions of practice:--the intellectual store of ideas applicable to the special department; the powerful action of the associating forces; a very clear perception of the end, in other words, sound judgment; and, lastly, that patient thought, which is properly an entranced devotion of the energies to the subject in hand, rendering application to it spontaneous and easy.