490 Official Correspondence on the attaching of 



statements associated with it, and we considered it right to 

 express our doubts, and thus afford an opportunity to Dr. 

 O'Shaughnessy to furnish further evidence by which we 

 and others might be satisfied ; this is no proper ground of 

 complaint, and Dr. O'Shaughnessy is doubtless too well ac- 

 quainted with the history of science in general, and of elec- 

 tricity in particular, to require to be more than reminded 

 that it is the course which under analogous circumstances 

 has invariably been followed, and that he by no means stands 

 alone in having to conform to it. We need only instance 

 the case of Dr. Wollaston, the whole of whose experiments 

 on the identity of common and voltaic electricity have been 

 called in question, because he mingled with his proofs an 

 experiment which had a resemblance, and nothing more, to a 

 case of decomposition by ordinary electricity ; nor were they 

 admitted among scientific facts till Faraday's recent researches 

 confirmed their general correctness. Dr. O'Shaughnessy 

 will also recollect the case of M. Colladon of Geneva, whose 

 conclusions as to the identity of magnetism and common elec- 

 tricity were doubted, or totally denied, although he asserted 

 the experiments on which they were founded had been wit- 

 nessed by MM. Arago, Ampere, and Savary, because these 

 gentlemen did not publish their admission of the results. We 

 have briefly adverted to these instances, taken from the his- 

 tory of electricity, to convince our readers that the expres- 

 sion of doubt, when the evidence of a scientific statement is 

 not complete, does not merit the title of " carping," and that 

 Dr. O'Shaughnessy in being required to substantiate his as- 

 sertions in greater detail than he had done, has not been 

 unfairly dealt with. 



In our former paper we were under the necessity of point- 

 ing out an instance in which Dr. O'Shaughnessy had entire- 

 ly misapprehended his opponent's meaning, and consequently 

 misrepresented his statements ; and we are now compelled to 

 point out a similar instance in which we have been the suf- 



