of the Solar Bays, rt^-lf .? 229 



In all these experiments the magnetism of the polished extre- 

 mity of the wire was North, excepting with the needles c and 

 g, in which it was South ; the focus of a lens was directed up- 

 on the needles during ten minutes, excepting in the experi- 

 ments on the 1 1th July with wire d, when it was 25', and that 

 with wire Z, when it was only 5'. 



In order to show the state of the wires during the solar 

 action, we fixed vertically the south pole below and the po- 

 lished half above the trial needle. The following experiment 

 was made in this manner on the 12th August : 



M. Poggendorf recommended to us to extend our experi- 

 ments to polarised light. For this purpose we sometimes em- 

 ployed a blackened mirror inclined S5° 2o" to the incident 

 solar ray, and sometimes a prism of calcareous spar. The 

 observations on this kind of light will be found in our me- 

 moir. It may be sufficient to state here, that it did not prove 

 more efficacious than direct light on the production of mag- 

 netism. 



From this analysis of our researches we think we are justly 

 entitled to reject totally a discovery y which, for seventeeji years, 

 has at different times disturbed science. The small variations 

 which are found in some of our experiments, and which we 

 have not concealed, cannot constitute a real action of the na- 

 ture of that which was observed by MM. Morichini, Baum- 

 gartner, &c. in so clear and decided a manner. These varia- 

 tions, besides, are not always favourable to the supposed dis- 

 covery. — Ann, de Chimie. 



