298 NATURAL HISTORY 



they were several bodies, but being both commixed, they 

 desire larger room. 



5. When any other beginning of motion concurs, besides 

 the overburthening of the air, it is an accessory which 

 strengtheneth and increaseth that principal, which is the 

 reason that great and violent winds do seldom rise, by the 

 simple overburthening of the air. 



6. Four things are accessory to the overburthening of 

 the air. The breathing out of subterraneal places : the 

 casting down out of (as it is called) the middle region of 

 the air ; dissipation made out of a cloud, and the mobility 

 and acrimony of the exhalation itself. 



7. The motion of the wind is for the most part lateral; 

 but that which is made by mere overburthening is so from 

 the beginning, that which is made by the expiration of the 

 earth, or repercussion from above, a little while after, unless 

 the eruption, or precipitation, or reverberation, be exceeding 

 violent. 



8. Air will endure some compression before it be over- 

 burthened, and begins to thrust away the adjoining air, by 

 reason whereof all winds are a little thicker than quiet 

 and calm air. 



9. Winds are allayed five ways, either by the conjunction 

 of vapours, or by their sublimation, or by transporting them, 

 or by their being spent. 



10. Vapours are conjoined, and so the air itself becomes 

 water, four ways, either by abundance aggravating, or by 

 colds condensing, or by contrary winds compelling, or by 

 obstacles reverberating. 



11. Both vapours and exhalations, but wind very fre 

 quently from vapours. But there is this difference, that 

 winds which are made of vapours do more easily incorpo 

 rate themselves into pure air, are sooner allayed, and are 

 not so obstinate as those winds which are engendered of 

 exhalations. 



12. The manner and several conditions of heat have no 

 less power in the generation of winds, than the abundance 

 or conditions of the matter. 



13. The heat of the sun ought to be so proportioned in 

 the generation of winds, that it may raise them, but not in 

 such abundance as that they gather into rain, nor in so 

 small a quantity, that they may be quite shaken off and 

 dispersed. 



14. Winds blow from their nurseries, and the nurseries 

 being disposed several ways, divers winds for the most part 



