114 GEORGE HERBERT STOCKBRIDGE 



into a workshop, just as the allurements of journalism tempt 

 the majority of the poets and historians away from their 

 natural callings. A sure sign of the tendency here pointed 

 out is that, whereas the main and almost the only sources 

 of information about scientific progress used to be the trans- 

 actions of royal or similar societies, or the technical press, 

 these enlighteners of the public mind now lag behind the pat- 

 ents, which might otherwise be endangered. But the genius 

 of Franklin was many sided, and as in philosophy and states- 

 manship one is compelled to admire both the keenness of 

 his insight, and the readiness with which he is able to reduce 

 his philosophy to maxims of statecraft or of personal con- 

 duct, so in science one can but marvel at his large compre- 

 hension, and at the ease with which he deduces underlying 

 principles or applies them in a perfected apparatus. 



William Sturgeon's electromagnet, invented in 1825, 

 consisted of a core of soft iron coated with an insulation of 

 varnish, and wound with a single spiral of bare wire. With 

 his first magnet the inventor sustained a weight of nine 

 pounds. One of the earliest and most important services 

 rendered by Joseph Henry to the progress of electrical knowl- 

 edge consisted in increasing the capacity of the Sturgeon 

 magnet by winding the core with many coils of wire previously 

 insulated with silk, the spiral being wound as nearly as pos- 

 sible at right angles to the core. Henry began his investi- 

 gations of the Sturgeon magnet soon after the year 1826, 

 when he became a teacher in the Albany academy; and he 

 pursued them with such success that within five years he 

 had constructed a magnet capable of sustainiing three thou- 

 sand six hundred pounds. 



The activity of Henry during these and the years im- 

 mediately following was marvelous. Side by side with his 

 labors in improving the magnet went countless experiments 

 to determine the best relations between the length and ar- 

 rangement of the coils, and the number and mode of coupling 

 of the battery plates. That this was not an obvious course 

 of investigation appears from the fact that, in the early days, 

 Henry was the only philosopher who gave adequate attention 

 to it. The battery as a source of energy was another subject 



