258 



SCIENCE OF GARDENING. 



Pa ax II. 



tains. TTiey will begin, in fair weather, to form some houK? after sunrise, arrive at their maximum in 

 the hottest part of the afternoon, then go on diminishing, and totally disperse about sunset. Previous to 

 rain the cumulus increases rapidly, appears lower in the atmosphere, and with its surface full of loose 

 fleeces or protuberances. The formation of large cumuli to leeward in a strong wind, indicates the ap- 

 proach of a calm with rain. When they do not disappear or subside about sunset, but continue to rise, 

 thunder is to be expected in the night. 



1241. The stratus has a mean degree of density, and is the lowest of clouds, its inferior surface commonly 

 resting on the earth in water. This is properly the cloud of night, appearing about sunset. It compre- 

 hends all those creeping mists which in calm weather ascend in spreading sheets (like an inundation of 

 water) from the bottoms of valleys, and the surfaces of lakes and rivers. On the return of the sun, the 

 level surface of this cloud begins to put on the appearance of cumulus, the whole at the same time separat- 

 ing from the ground. The continuity is next destroyed, and the cloud ascends and evaporates, or passes 

 oft" with the appearance of the nascent cumulus. This has long been experienced as a prognostic of fair 

 weather. 



1242. Transition of forms. The cirrus having continued for sometime increasing or stationary, usually 

 passes either to the cin-o-cumulus or the cirro-stratus, at the same time descending to a lower station in the 

 atmosphere. This modification forms a very beautiful sky, and is frequently in summer an attendant on warm 

 and dry weather. The cirro-stratus, when seen in the distance, frequently gives the idea of shoals of fish. 

 It precedes wind and rain ; is seen in the intervals of storms ; and sometimes alternates with the cirro- 

 cumulus in the same cloud, when the different evolutions form a curious spectacle. A judgment may be 

 formed of the weather likely to ensue by observing which modification prevails at last. The solar "and 

 lunar halos, as well as the parhelion and paraselene (mock sun and mock moon), prognostics of foul wea- 

 ther, are occasioned by this cloud. The curnulo-stratus precedes, and the nimbus accompanies rain. 



12^13. Dew is the moisture insensibly deposited from the atmosphere on the surface of 



