VOL. IV.] PHILOSOPHICAL TRANSACTIONS. 389 



ourselves to certain fixed laws of dissecting each part. Of the necessity of this 

 change he brings manifest proofs; and having done so, he alleges the reason 

 why he says nothing of the use of the parts of the brain, nor of the actions 

 called animal, it being impossible to explain the motions that are made by an 

 engine, if the fabric of the parts be not known ; and those anatomists rendering 

 themselves ridiculous, that discourse so magisterially of the use of the parts, of 

 which they know not the structure. 



Last of all, he observes, that for the acquiring of some good knowledge of 

 the brain, there must be dissections and examinations made of as many heads 

 as there are different species of animals, and different states and conditions of 

 each kind ; since that in the fetuses of animals it will be seen how the brain 

 is formed ; and what could not be seen in sound and entire brains may be seen 

 in such as have been changed by sickness. 



[This account of Steno's work is followed in the original by a minute, but 

 uninstructive analysis of Dr. Wittie's Answer (mentioned in N° 49) to Symp- 

 son's Hydrologia Chymica, noticed at p. 303 of this vol. of our Abridgment.] 



An Account of divers Minerals, thrown up and hurned hy the late Fire 

 of Mount Mtna. By some ingenious Merchants of England, 

 ' N' 52, p. 1041. 



As the examination of the matters thrown up from fiery mountains may best 

 explain the cause of such eruptions, we publish the following account received 

 by a ship lately arrived from Messina. 



First, a quantity of ashes, taken up in divers parts of and about ^tna; 

 some at the top or mouth of the new made mountain ; some a mile off, some 

 four, some ten miles, some but half a mile distant, and others on the skirts of 

 the said mountain ; whereof the four first were found to agree well enough 

 with their distances, but the last two to differ much both from the former and 

 from one another ; the former four sorts having been found very dry like dust, 

 but the two latter being still very moist, though long exposed to the hot sun ; 

 besides that the last two differ from one another, as one sort of them consists 

 of hard and small lumps, the other of very soft dirty grains, yet both moist and 

 of a vitriolate taste. 



Secondly, some of the cinders or sciarri, taken up at some distance from the 

 mouth ; and of the coarser some are black, with a crust of brimstone, some 

 of a red hue, others finer, said to be got out of the gutters of fire at the very 

 mouth. Both these kinds are light ; but there is a third sort of stone, very 



