t 40S J 



LXX1T. Tro r C( dings ofLearne'l Societies* 



ROYAL SOCIETY. 



IVl ay 4. — A paper was read on the triple sulphurct of lead, 

 copper, and antimony, discovered by count Bournon in 

 Cornwall. Mr. Jameson proposed to call this mineral Bour- 

 nonite; but the count, in this additional memoir, in which 

 lie corrects the mistakes he made respecting the figure of its 

 Crystals in a former paper, prefers the name of the place 

 where it was found. The integral molecule of this mineral 

 pe has determined not to be a perfect cube, as at first con- 

 cluded, but having dissimilar sides in the proportion of 3 to 

 5. The count, in answer to a paper of Mr. Smithson in the 

 Philosophical Transactions, defends the existence, not only 

 or binary but also of ternary and quaternary compounds, 

 and proves that the mineral in question is an example of the 

 latter combination, a quaternary sulphuret. As an instance 

 of the very singular difference in minerals in consequence of 

 this variety of combination, the count refers to the anhy- 

 drous sulphat of lime, which is so very different from com- 

 mon gypsum, although composed o'f the same materials 

 with the addition only of a little water. 



May 10. — A paper by Mr, Home, on the Squalus 

 vnaximys, was read, stating some particulars of the dimen- 

 sions and conformation of the different basking sharks which 

 have been thrown on the coast of Britain in tlie course of 

 the last year. The author considers this species of shark as 

 occupying an intermediate place between the mammalia 

 (whales) and fishes, and partaking of the characters of both. 



May 18, — Capt. Burney stated to the Society some more 

 particulars respecting the floating of heavy bodies in a 

 stream, and the nature of their moving faster than the cur- 

 rent. He seemed to consider the cause of all such motion 

 to be owing to the pressure of the atmosphere. 



Mr. Cavendish laid a paper before the Society on the me- 

 thods of dividing mathematical instruments, in which he 

 proposed to substitute a balance compass and microscope for 

 Mr. Troughton's cylindrical ruler. 7"he plan was illustrated 

 by a drawing of the instrument, which effected the purpose 

 , without 



