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K FARMERS' KK GIST Ell. 



Vol. 5. 



JULY 1, 1837. 



No. 3. 



EDMUND RUFFIN, EDITOR AND PROPRIRTOR, 



From the American Jouriiul of Science. 



NOTICE OF TIIR KLKCTRO-:\rAG]VETIC MA- 

 CIUNK OF 311?. THO.llAS UAVKiNPORT, OF 

 BRANIJOX, N13AU RUTLAND, VERSIOKT. 



Many years have passed since motion was first 

 prodiired by galvanic power. The dry cohiiniis 

 of !)e Lie and Zainboni caused the vibration ol' 

 delicate pendulums and the riuLiinu; of small bells, 

 lor long periods of time, even several years, with- 

 out intermission. 



In lSlO-20, Prof. Oersted, of Copenhairen, 

 discovereil, that magnetism wasenvolved between 

 the poles of a galvanic battery. Prof. Sweigijer, 

 of Halle, Gemany, by his galvanic multiplier, 

 succeeded in rendering the power manliest, when 

 tiie ijalvanic battery was nothing more than two 

 small wires, one of co|)per 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 convolu- 

 tions o(" insulated wire, and was thus augmented 

 so as to deflect the magnetic needle sometimes 

 even 90"'. Prof. Muii, of Utretcht, by winding 

 insulated wire around soft iron, imparted to it pro- 

 digious magnetic power, so that a horse-shoe bar, 

 thus provided, and connected with a galvanic 

 battery, would litl over one hundred pounds. 

 About the same time, Mr. Joseph Henry, of Al- 

 bans', now Prof! Henry, of Princeton Colleire, 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 oi" corresponding size; nor did he 

 desist, until, a short time after, he lifted thousands 

 of pounds, bv 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 at- 

 tempt of his is recorded in this Journal, Vol. xx. p. 

 340. A power was thus appli(!d to the movement 

 of a machine, by a beam sus|)endcd in the centre, 

 which performed reirular vibrations in the manner 

 of a beam of a steam engine. This is the origi- 

 nal application from which have sprung, or at 

 least to which have succeeded, several similar at- 

 tempts, both in this country and in Europe. A 

 galvanic machine was reported to the Britisli As- 

 sociation in 1835, by Mr. McGauly, of Ireland, 

 and he has renewed his statements of successfljl 

 experiments at the late meeting at Bristol. Mr. 

 Sturgeon, of Woolwich, England, also reports a 

 galvanic machine as being in use on his prf^mises 

 lor pumping water, and for other n)eclianical pur- 

 poses.* 



But, I believe that Mr. Davenport, named at 

 the head of this notice, has been more successllil 

 than any other person in the discovervf of a gal- 

 vanic machine of great simplicity and efRciency. 



* Sturgeon's Annals of Electricity, Magnetism, &,c. 

 No. 1, Vol. 1. October, 1836. 



t Mr. Davenport appears to have been strictly the 

 inventor of a luetfiod of applynig jjalvaiiism to pro- 

 duce rotary inotioa. 



Vol. V— 17 



During the last two or three years, much has been 

 said of this discovery in the newspapers, and it i? 

 probable, that in a future number of' this journal, 

 drawings and an accurate description of the ma- 

 chn)e may be given. Having been recently invi- 

 ted to examine a working model, in two varieties 

 of form, and to report the result, I shall now at- 

 tempt nothing more tlian a general descri|itioii, 

 such as avay render intelligible the account I am 

 to give. 



1. The Rotary Machine, composed of revolv- 

 ing electro-magnds, with fixed permanent mag- 

 }iets. 



Tills machine was brought to New Haven 

 March 16, 1837, by Mr. L<rael Slade, of Troy, 

 New York, and by him set in motion for my ex- 

 amination. The moving part is composed of" two 

 iron bars placed horizontally, and crossing each 

 other at riijht angles. They are both five and a 

 half inches long, and they are terminated at each 

 end by a segment of a circle ma<le of soft iron ; 

 these segments are each three inches long in the 

 chord line, and their position as they are suspen- 

 ded upon the ends of the iron bars, is horizontal. 



This iron cross is sustained by a vertical axis, 

 standing with its pivot in a socket, and admitting 

 of easy rotation. The iron cross bars are wound 

 with copper wire, covered by cotton, and they are 

 made to form, at pleasure, a proper connexion 

 with a small circular battery, made of concentric 

 cylinders ol" copper and zinc, which can be im- 

 mersed in a quart of acidulated water. Two sem- 

 icircles of stronijly magnetized steel form an en- 

 tire circle, interrupted only at the two opposite 

 poles, and within this circle, which lies horizontal- 

 ly, the CTulvanized iron cross moves in such a man- 

 ner that its iron segments revolve parallel and very 

 near to the magnetic circle, and in the same plane. 

 Its axis, at its nppei end, is fitted by a horizontal 

 co<^-ivheel to another and larger vertical wheel, to 

 whose horizontal axis, weiirht is attached and 

 raised by the windini; of a rope. As soon as the 

 small battery, destined to generate the power, is 

 properly connected with the machine, and duly 

 excited by diluted acid, the motion beoins, by the 

 horizontal movement of the iron cross, with its 

 circular segments or flanges. By the ijalvanic 

 connection, these crosses and their connected se<r- 

 ments are masnetized, acquiring north and south 

 polaritjr at their opposite ends, and being thus sub- 

 jected to the attracting and repellini^ force of the 

 circular fixed mao;nets, a rapid horizontal move- 

 ment is produced, at the rate of two hundred to 

 three hundred revolutions in a minute, vvhen the 

 small battery was used, and over six hundred with 

 a calorimotor of large size. The rope was wound 

 up with a weiirht of fourteen pounds attached, and 

 twenty eight pounds were lilted from the floor. 

 The movement is instantly stopped by breaking 

 the connexion with the battery, and then reversed 

 by simply interchanging the connexion of the 

 wires of the battery with those the machine, 

 when it becomes equally rapid in the opposite di- 

 rection. 

 The machine, as a philoeophical instrument, 



