CHAP. 1. 8. OF CLOUDS. 23 



SECTION VIII. 



Of the Nimbus or Raindoud. PI. V. Fig. 1. 

 NIMBVS. Def. NVBES VEL NVBIVM CONGERIES PLVVIAM 



EFFVNDENS. 



CLOUDS of any one of the aforementioned 

 modifications, at the same degree of elevation, 

 may increase so much as completely to obscure 

 the sky: two or more different modifications 

 may also do the same thing in different eleva- 

 tions, and the effect of this obscuration may be 

 such as would induce an inattentive observer 

 to expect the speedy fall of rain. It appears, 

 however, from attentive observation, that no 

 cloud effuses rain until it has previously under- 

 gone a change sufficiently remarkable to con- 

 stitute it a distinct modification, to which the 

 term nimbus has v properly been applied.* This 



* This application of the word nimbus corresponds very 

 well with the sense in which it was taken by some of the old 

 Roman writers, who considered it as a stormcloud, and dis- 

 tinguished from imber or a shower of rain actually falling. 

 Thus Lucretius 



Copia nimborum, turba majore coacta 



Urguens ex supero premit ac facit effluere imbris. 



Lucr. de Rcr. Nat. vi. 512. 



