323 



the transmitted light is green ; but when the axis is perpendicular to 

 that plane, the transmitted light is blue. A solution of the salt ex- 

 hibits the same general action upon light as the solid, with the excep- 

 tion of double refraction. This salt has also the peculiar property of 

 exciting a specific action upon a definite red ray, situated near the 

 extremity of the red portion of the spectrum. 



February 19, 1S35. 

 Sir JOHN RENNIEj Knt. Vice-President, in the Chair. 



A paper was read, entitled, " On the probable Position of the 

 South Magnetic Pole." By Edward Radge, Esq., F.R.S., &c. 



The recent discovery of the site of the North Magnetic Pole, which 

 has resulted from the experiments of Capt. James Ross, suggested 

 to the author the inquiry whether any similar indications of an ap- 

 proach to the South Magnetic Pole can be gathered from any obser- 

 vations now on record. With this view a table is given of the obser- 

 vations made by Tasman in 1642 and 1643, during his voyage of 

 discovery in the Southern Ocean, extracted from his journal ; from 

 which it appears that he on one occasion noticed the continual agita- 

 tion of the horizontal needle, in south latitude 42° 25', and longitude 

 from Paris 160 c . On the presumption that the South Magnetic Pole 

 was at that time near this spot, and that it has since been retrograd- 

 ing towards the East, the author conjectures that it will now 7 be found 

 in or about the 43rd parallel of south latitude ; and to the south-east 

 of the Island of Madagascar, a situation extremely convenient for 

 ascertaining its exact position, which he considers as an object of 

 great theoretical as well as practical importance. 



The reading of a paper was then commenced, entitled, " An Ex- 

 perimental Inquiry into the Cause of the grave and acute Tones of 

 the Human Voice." By John Bishop, Esq. Communicated by 

 P. M. Roget, M.D., Sec. U.S. 



February 26, 1835. 



JOHN WILLIAM LUBBOCK, Esq., Vice-President and Trea- 

 surer, in the Chair. 



The reading of a paper, entitled, " An Experimental Inquiry into 

 the Cause of the grave and acute Tones of the Human Voice." By 

 John Bishop, Esq. Communicated by P. M. Roget, M.D., Secretary 

 to the Royal Society, was resumed and concluded. 



The author considers all the theories hitherto proposed respecting 

 the functions of the organs of the human voice, as not only unsatis- 

 factory, but as beinsj founded on erroneous views. He shows that 

 the modulation of the tones of the voice is not the result of variations 



