APPENDIX, 



JVotice of the Electro-Magnetic Machine of Mr. Thomas Davenport, 

 of Brandon, near Rutland, Vermont. 



Many years have passed since motion was first produced by gal- 

 vanic power. The dry columns of De Luc and Zamboni caused 

 the vibration of delicate pendulums and the ringing of small bells, 

 for long periods of time, even several years, without intermission. 



In 1819-20, Prof. Oersted, of Copenhagen, discovered, that mag- 

 netism was evolved between the poles of a galvanic battery. Prof. 

 Sweigger, of Halle, Germany, by his galvanic multiplier, succeeded 

 in rendering the power manifest, when the galvanic battery vi^as noth- 

 ing more than two small wires, one of copper and the other of zinc, 

 immersed in as much acidulated water as was contained in a wine 

 glass. The power thus evolved was made to pass through many 

 convolutions of insulated wire, and was thus augmented so as to 

 deflect the magnetic needle sometimes even 90*^. Prof. Moll, of 

 Utretcht, by winding insulated wire around soft iron, imparted to it 

 prodigious magnetic power, so that a horse shoe bar, thus provided, 

 and connected with a galvanic battery, would lift over one hundred 

 pounds. About the same time, Mr. Joseph Henry, of Albany, now 

 Prof. Henry, of Princeton College, by a new method of winding 

 the wire, obtained an almost incredible magnetic force, lifting six or 

 seven hundred pounds, with a pint or two of liquid and a battery of 

 corresponding size ; nor did he desist, until, a short time after, he 

 lifted thousands of pounds, by a battery of larger size, but still very 

 small, (1830.) 



This gentleman was not slow to apply his skill to the generation 

 of motion, and a successful attempt of his is recorded in this Journal, 

 Vol. XX. p. 340. A power was thus applied to the movement of a 

 machine, by a beam suspended in the center, which performed reg- 

 ular vibrations in the manner of a beam of a steam engine. This is 

 the original application from which have sprung, or at least to which 

 have succeeded, several similar attempts, both in this country and in 

 Europe. A galvanic machine was reported to the British Associa- 

 tion in 1835, by Mr. McGauly, of Ireland, and he has renewed his 



Vol. XXXn.— No. 1. A 



