1814.] Imperial Institute. 389 



merous veins of granite may be traced from the rock of granite, 

 into the schist. Some of these veins may be observed upwards of 

 50 yards, till they are lost in the sea; and in point of size vary 

 from a foot and a half to less than an inch. It may deserve notice 

 that as the felspar is of a flesh colour, it is impossible for any 

 observer Vo consider them as quartz veins ; one of these large veins 

 is dislocated and heaved several feet by a cross course of quartz, 

 and fragments of schistus having the appearance of veins are found 

 in the granite veins. At one place the author observed a very 

 curious and satisfactory phenomenon. He found that one of these 

 veins of gtanite, after proceeding vertically some distance, suddenly 

 formed an angle, and continued in a direction nearly horizontal for 

 several feet with schistus both above and below it, which appearance 

 most completely destroys one of the theories suggested for the 

 explanation of similar veins at St. Michael's Mount, viz. that a 

 ridge of granite had been left, and clay slate deposited afterwards 

 on its lides. 



At the same meeting a paper from Mr. Joseph Carne, Esq. was 

 read, giving a more ample account of the Relistian Mine than that 

 published in the Philosophical Transactions, accompanied by some 

 interesting sections, and a plan of its lodes. 



At this meeting also some account of the sand found at Piran was 

 descrilied by Dr. Paris, tlie Secretary to the Society. It appears 

 that Nature is actually at this time, by some mysterious process, 

 converting this sand into stone, and specimens of it are found in 

 different states of induration. A further account of this very inte- 

 resting subject will be given in a future number of the Journal. 



We are happy to state that this useful Society is very considerably 

 increased in numbers since our last report of it, having already 

 inroUed the names of more than an hundred active and intelligent 

 members. 



IMPERIAL INSTITUTE OF FRANCK. 



Account of the Labours of the Class of Mathematical and Physical 

 Sciences of the Imperial Institute of France during the Year 1813. 



Memoir of M. Burckhardt on the Quantity of Matter in the 

 Planets. 



(Continued fiera p. 309.) » 



On the small Equations which exist in the Theory of Jupiter. 



The analytical calculus, notwithstanding the precision to which 

 it has been brought by mathematicians, has still its imperfections as 

 well as the best instruments. For want of direct methods, the 

 equations can only be integrated by means of scries, all the terms 

 of which considered as sensil)le are taken, while the rest are neg- 

 lected. In fact each term omitted is probaljly so small that if it 

 were alone it might be very properly neglected ; but the total 

 number of these is so great that notwithstaiuruig all the conipensa- 

 tjons that may be hoped for, it is not impossible but the total error 



