724 COSMOS. 



more correct view was taken up by Halley late in the 

 eighteenth century, and was then more fully and satisfactorily 

 explained with reference to the action of the velocity of rota- 

 tion peculiar to each parallel of latitude. Halley, prompted 

 by his long sojourn in the torrid zone, had even earlier 

 (1686) published an admirable empirical work on the geo- 

 graphical extension of trade winds and monsoons. It is sur- 

 prising that he should not have noticed, in his magnetic expe- 

 ditions, the law of rotation of the winds, which is so important 

 for the whole of meteorology, since its general features had 

 been recognised by Bacon and Johann Christian Sturm of 

 .Hippolstein (according to Brewster, the actual discoverer of 

 the differential thermometer.*) 



In the brilliant epoch characterised by the foundation of 

 mathematical natural philosophy, experiments were not want- 

 ing for determining the connection existing between the 

 humidity of the atmosphere, and the changes in the tem- 

 perature and the direction of the winds. The Academia del 

 Cimento had the felicitous idea of determining the quantity of 



intervallo sopravanza le maggiori altezze delle montagne ; la qual 

 pozzion d'aria tanto meno dovra esser renitente alia conversion terrestre, 

 quanto che ella e ripiena di vapori, fumi, ed esalazioni, materie tutte 

 participant! delle qualita terrene : e per conseguenza atte nate per lor 

 natura (?) a i medesimi movimenti. Ma dove, mancassero le cause del 

 moto, cioe dova la superficie del globo avesse grancli spazii piani, e merio 

 vi fusse della mistione de i vapori terreni, quivi cesserebbe in parte la 

 causa, per la qtiale V aria ambiente dovesse totalmente obbedire al 

 rapimento della conversion terrestre ; si che in tali uoghi, mentre che la 

 terra si volge verso Oriente, sidovrebbe sentir continuamente un vento, 

 che si ferisse, spirando da Levante verso Ponente ; e tale spiramento 

 dovrebbe farsi piu sensibile, dove la vertigine del globo fusse piu veloce : 

 il che sarebbe ne i luoghi piu remoti da i Poli, e vicini al cerchio 

 massimo della diurna conversione. L'esperienza applaude molto a questo 

 filosofico discorso, poiche ne gli ampi mari sottoposti alia Zona torrida, 

 dove anco 1'evaporazioni terrestri mancano (?) si sente una perpetua 



aura muovere da Oriente " 



* Brewster, in the Edinburgh Journal of Science, vol. ii. 1825, 

 p. 145. Sturm has described the Differential Thermometer in a little 

 work, entitled Collegium experimentale curiosum, (Nuremberg, 1676,) 

 p. 49. On the Baconian law of the rotation of the wind, which was first 

 extended to both zones, and recognised in its ultimate connection with 

 the causes of all atmospheric currents, by Dove, see the detailed trea- 

 tise of Muncke, in the new edition of Gehler's Physical. Wo'rterbucli, 

 Bd. x. S. 20032019 and 20302035. 



