226 PREFACE TO THE 



rei minime obliti sumus ; sed earn nobis ipsis reservavi- 

 mus; cum de aliorum industria in hac re, priusquam 

 homines cum natura paulo arctius consuescere incep- 

 erint, prolixe spondere non audeamus." 



Compare these announcements with the following pas- 

 sage in the preface to the fragment before us. " Atque 

 a phaenomenis aBtheris ordiri solennius foret. Nos au- 

 tem, nil de severitate instituti nostri remittentes, ea ante- 

 feremus quse naturam constituant et referant magis com- 

 munem, cujus uterque globus est particeps. Ordiemur 

 vero ab historia corporum secundum earn differentiam 

 quae videtur simplicissima ; ea est copia aut paucitas ma- 

 terice intra idem spatium sive eandem circumscriptionem 

 contentce et exporrectae." l The subject therefore which 

 stands first in the list of these cardinal virtues in nature 

 which, when he published the Novum Organum, he 

 meant to reserve for his own pen and handle separately, 

 namely, the Historia Densi et Ran is the very 

 subject with which this fragment commences ; and there 

 need be no doubt that both the title and the praefatio 

 properly belong to it. 



There is nothing that I know of to determine the 

 date at which it was written. But there being no allu- 

 sion to it in the Commentarius Solutus, I suppose it was 

 not begun in 1608. And it must certainly have been 

 written before 1622, when the Historia Ventorum was 

 published ; for then the Historia Densi et Rari was de- 

 signed for the second place in the series, not (as here) 

 for the first. The allusion in the last paragraph but one 

 to an instrument recently exhibited in England by cer- 

 tain Batavians, which uttered a musical sound when 

 exposed to the sun, may possibly bring the uncertainty 



l See p. 234. line 19. from the top. 



