Descriplion of a Galvanic Clod:. 261 



of fatigue to what the traveller undergoes who visits the Alps. 

 That the ascent must be hazardous in a storm of hail and snow 

 there can be no doubt, but to cross Salisl)ury plain may some- 

 times be dangerous. Yet stripped of poetical terrors" and di- 

 vested of the elo(juent description of some writers, there is per- 

 haps no mountain in Eurojje, the ascent of which does not fur- 

 nish more difficulties than the Peak of TenerKfe. 



XLV. On Electro-galvnnic Agency employed as a Moving 

 Power ; wil/i a Description of a Galvanic Clock. By 

 Francis Ronalds, Esq. of Hammer smiih. 



To Mr. Til loch. 



Sir, — 1 SEND you a drawing and description of a contrivance 

 for applying the electricity of M, De Luc's column to the mo- 

 tion of indexes, which arose out of my attempts to facilitate his 

 ingenious method of observing its extraordinary phaenomena. 

 If any of the readers of your useful Magazine, by improving ujion 

 the method I have stated of regulating the power of the column, 

 or by substituting a better, were to render it subservient to the 

 measurement of time, it would give me great pleasure. 



I believe M. De Luc first applied a column of 600 groups to 

 the motion of a small gold bead, suspended by a silken thread 

 between two balls, each of which was connected with tlie oppo- 

 site extremity ; but not having succeeded by this means in ob- 

 taining a vibration sufficiently regular and constant for his ob- 

 servations on its variable action, he abandoned it for one much 

 better adapted to his purpose : he suspended the small gold head 

 by the finest silver wire from a hook connected with the positive 

 extremity, which hung Avhen unelectrified close to a ball also 

 connected with the same extremity ; but, when the column Avas 

 active, it receded from this ball, and discharged the electricity 

 ot the positive end upon a ball connected with the negative ex- 

 tremitv, or v.ith the ground, or with both ; after which it fell by 

 its gravitation into the first position. He also placed a cross wire 

 altove the head to prevent it from striking, and afterwards sub- 

 stituted a gilt pith ball of the size of a pea, for the bead, and ex- 

 tended his number of groups to 1300 of li inch square: this 

 apparatus continued in motion more than two years, (and has 

 not that I know yet ceased,) varying in the number of vibrations 

 in a minute from forty-five down to scarcely one. 



But Mr. B. M. Forster had constructed a similar kind of 

 apparatus to that which M. De Luc first employed, which kept 

 a pair of bells ringing several months ; and Mr. William Allen 



K 3 extended 



