242 Mr. Sturgeon on Electro-Magrietism. 



expected that he might have recollected so much of it, at 

 least, as to have indicated the points of agreement between 

 my theory and that of M. du Petit-Thouars. But I am very 

 sure my young friend has here been guilty of inadvertence 

 only, and of no disrespect towards me ; any more than in his 

 preface to the work of M. Richard on Fruits and Seeds, where 

 Mr. Lindley overlooks all that has been done in England for 

 the advancement of botany, and the correction of Linnaeus, 

 for 30 or 40 years past, particularly through the use that has 

 been made of the Linnaean herbarium, and the labours of the 

 Banksian school, whence all Europe has been enlightened 

 and improved in natural science. The artificial system of 

 Linnaeus has indeed facilitated the acquisition and the diffu- 

 sion of botanical knowledge; but the chief good which all 

 natural science owes to this philosopher consists in his prin- 

 ciples of definition, description, and nomenclature, as well as 

 in the ideas he first suggested of natural orders and affinities, 

 always protesting, as he did, against forcing such orders into 

 artificial systems. 



By the preceding observations I am far from claiming any 

 priority of discovery over M. du Petit-Thouars. Mr. Lindley 

 does not fix the date of his works, nor have I ever seen them. 

 I feel myself sufficiently honoured by the coincidence of our 

 opinions. His ideas of buds are new to me, and elucidate 

 the rest of his theory. I should, however be cautious in ad- 

 mitting all his analogies, however ingenious. Analogy is a 

 treacherous guide in philosophy, and metaphysics are out of 

 place in natural science. It is far easier to speculate inge- 

 niously, than to observe accurately and reason wisely. 

 I remain, gentlemen, 



Your very obedient servant, 

 Norwich, Sept. 30, 1824. James Edward Smith. 



XLII. On Electro- Magnetism. By Mr. W. Sturgeon. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 



TN no experiment hitherto recorded in the whole history of 

 -*■ electro-magnetic rotations, do we find employed, at the 

 same time, both poles of the straight bar magnet. Hence all 

 the rotating phenomena yet elicited, by employing that mag- 

 net, are only such as obtain by the reciprocal action of one of 

 its poles, and a portion of the conducting wire (under various 

 forms) joining the copper and zinc sides of the battery. And 



when 



