On the Jnatomy and Physiolngij of the Brain. 215 



there remain suspended from beinj dissolved in water, air or 

 other fluids, and consequently from the obstacle thu'i presented 

 to their fall bv the lower part of the atmosphere, in the same 

 way as the clouds, which, akhough specifically heavier than the 

 airj nevertheless keep svispended in it without being dissolved. 



But supposing for an instant the dissemiriation in the upper 

 parts of the atmosphere of the principles of aerolites, how, it 

 may be asked, can these principles so disseminated, and proba- 

 bly'in minute division, be united, and form masses so considerable 

 as those which are said to have fallen ? 



This question is doubtless of most difficult solution: we may, 

 however, hazard a probable answer. 



In fact, it is agreed on all hands, that the fall of aerolites 

 takes place in storms, and particularly after explosions of thun- 

 der. 



On the other hand, M. Monge, in his excellent memoir on 

 Meteorology, has supposed with great probability that the noise 

 of thunder was owing to the vacuum produced by a cause not 

 yet ascertained, and immediately filled up by the strata of sur- 

 rounding air. 



It is not impossible, therefore, that the constituent principles 

 of aerolites, being transported by chemical or mechanical means 

 into the upper regions of the atmosphere, where the vacuum is 

 produced which occasions the noise of thunder, there remain 

 suspended by causes to which I have already alluded, until this 

 vacuum is ])roduced ; and then these principles, although dis- 

 seminated, being pressed by the external strata which fill the 

 vacuum, unite, conglomerate, and form a mass, the more consi- 

 derable in j)roportion to the quantity v.hich it meets with in 

 this place. 



XXXV. Of the Anatomy and Physiohgy of the Brain and 

 Nervous System, as taught by Drs, Gall and Si'vrzheim*. 



ziLL improvements in natural history, and particularly in the 

 natural history of man, are interesting, and deserve to be recorded 

 and published, in order to enable society in general to avail 

 themselves of the labours of those ingenious and persevering in- 

 dividuals to whom the investigation of nature is a passion, and 

 the discovery of truth a sufficient reward for their undertakings. 

 Viewing in tins light the important discoveries relative to the 

 anatomy and physiology of the brain, recently made by Gall 

 and Spurzhcim, it aeems expedient to communicate a short ac- 



* from a CoiTcsjioiuieut. 



O 4 Kount 



