Powerful Magnets 1 1 5 



and his method and apparatus for making thermometers, 

 which was followed by a letter from Mr. Welch to Mr. Gassiot 

 describing in detail the system followed at Kew Observatory 

 in electrical and meteorological observations. 



At the 33rd meeting (Nov. 2ist) Colonel Sabine said he had 

 received from Dr. Wolfgang Haecker, of Nuremberg, a horse- 

 shoe magnet, weighing 35 grains, capable of supporting, if 

 certain precautions were taken, 4785 grains (135 times its 

 own weight). Mr. Gassiot remarked that the same maker 

 had sent one to him, weighing 40 grains, which had held 

 up a total weight of 4599 grains (115 times its own weight). 



At the 34th meeting (Dec. l ) Colonel Sabine said that 

 a magnet, weighing 36 grains, had now been received from 

 Dr. Haecker, which supported 5280 grains, or 146 times 

 its own weight. 



Mr. Grove drew attention to an effect produced on the 

 retina by rubbing the eye before looking through a lens, 

 placed at one end of a tube, when striae, crossing one 

 another, make their appearance. For instance, if a convex 

 lens of one-inch focal length be thus placed in a tube six 

 inches in length, and the light of a candle, placed one foot 

 from the other end, be viewed through a pin-hole in it, 

 after the eye has been slightly pressed by the finger, these 

 striae are visible, accompanied occasionally by black spots, 

 which he attributed to the derangement of small vessels 

 and secretions in the eye, which were thus rendered' visible. 



1851. On Jan. 3oth, the 35th meeting, Mr. Grove 

 exhibited specimens from Dr. Schonbein, 2 of Basle, illustrat- 

 ing the effects of insolated oxygen on such chemical 

 substances as sulphide of antimony, of arsenic, and of lead, 

 but which were not produced by oxygen, kept in the dark. 



Professor E. Forbes read a letter from M. Puggaard, of 

 Copenhagen, on the geology of the Island of Moen. 3 He 



1 Figure omitted. 



* Christ. Fried. Schonbein, born at Wurtemberg, 1799, died at Baden 

 Baden 1868, appointed Prof, of Chemistry at Basle 1828, who did some 

 important work, especially in organic chemistry. 



3 Described by him in Moens Geologic (1874). 



