440 PROCEEDINGS OF 



but to repeat the names of tbis scientific host, would fill a volume. Confining the 

 inquiry to our own country would still transcend the limits of an address. Omit- 

 ting, then, the whole range of hyperphysical knowledge, I shall confine my in- 

 quiries to the various improvements and discoveries made by our countrymen in 

 the inductive sciences. It is said we have not contributed, in this respect, our 

 share to the mighty mass of accumulated knowledge of the world. But it could 

 not be expecied that a nation whose existence as such is less than a century 

 could, in that brief period, have equalled the discoveries of thousands of years. 

 Without boasting, however, of our achievements, an impartial examination will 

 show that our countrymen have greatly contributed to the modern improvements 

 and discoveries in the various departments of the inductive sciences. 



And, first, of electricity. This lias been cultivated with the greatest success in 

 our country, from the time when Franklin with his kite drew down electricity 

 from the thunder cloud, to that when Henry showed the electrical currents produced 

 by the distant lightning discharge. In Franklin's day tho idea prevailed that there 

 were two kinds of electricity, one produced by rubbing vitreous substances, the 

 other by the friction of resinous bodies. Franklin's theory of one electric fluid in 

 all bodies, disturbed in its equilibrium by friction, and thus accumulating in one 

 and deserting the other, maintains its ground, still capable of explaining tlie facts 

 elicited in the progress of modern discovery. Franklin believed that electricity 

 and lightning were the same, and proceeded to the proof. He made the perilous 

 experiment, by exploring the air with a kite, and drawing down from the thunder 

 cloud the lightning's discharge upon his own person. The bold philosopher re- 

 ceived unharmed the shock of the electric fluid, more fortunate than others who 

 have fallen victims to less daring experiments. The world was delighted with the 

 discoveries of the great American, and for a time electricity was called Franklin- 

 ism on the continent of Europe ; but Franklin was born here, and the name was 

 not adopted in England. While Franklin made experiments, Kinnersley exhibit- 

 ed and illustrated them, and also rediscovered the seemingly opposite electricities of 

 glass and resin. Franklin's lightning rod is gradually surmounting the many dif- 

 ficulties with which it contended, as experience attests the crreater safety of houses 

 protected by the rod, properly mounted, whilst the British attempt to substitute 

 balls for points has failed. This question, as to powder magazines, has lately ex. 

 cited much controversy. Should a rod be attached lo the magazine, or should it 

 be placed upon a post at some distance ? Tills question has been solved by Henry. 

 When an electrical discharge passes from one body to another, the electricity in 

 all the bodies in the neighborhood is affected. Henry magnetized a needle in a 

 long conductor, by the discharge from a cloud, more than a mile from the con- 

 ductor. If a discharge passes down a rod, attached to a powder house, may it 

 not cause a spark to pass from one receptacle for powder to another, and thus in- 

 flame the whole ? The electrical plenum, which Henry supposed, is no doubt dis- 

 turbed, and to great distances ; but the effect diminishes with the distance. If 

 all the principal conductors about a building can be oonneclod with a lightning 

 rod, there is no danger of a discharge ; for it is only in leaving or entering a con- 

 ductor that electricity produces heating effects : but if not, the rod is safer at a 

 moderate distance from the building. The rate at which electricity moved wa« 

 another of tho experiments of Franklin. A wire was led over a great extent of 

 ground, and a discharge passed through it. No interval could bo perceived be- 

 tween the time of the spark passing to and fron> tho wire at the two ends. Not 



