252 ASTRONOMY. 



The cirrus appears low and thick before a storm, and is usually in a 

 quarter opposite to that in which the storm arises. Steady, high winds, 

 are also preceded, and attended by cirrous streaks of a torn and scattered 

 character, and sometimes in the direction of the wind quite across the 

 sky. 



The cwmilus has the densest structure, is formed in lower atmosphere, 

 and moves with the current next the earth. In fair weather they will 

 sometimes begin with a small lump at sunrise, increasing through the 

 day and dispersing at sunset. It is a sign of rain, and encreases rapidly 

 before a storm. 



The stratus is the lowest of clouds, its lower surface commonly resting 

 on the earth. It is, properly, the cloud of night, appearing about 

 sunset, and comprehends all those morning mists which are usually the 

 precursors of fine weather. A constant intermixture of these forms 

 takes place in the dull season, and if they are studied carefully, will 

 soon enable a person to judge with tolerable accuracy of the nature of 

 the coming weather. The final prevalence of a particular form will 

 decide the weather. The cumulo-stratus precedes and the nimbus 

 accompanies rain. 



CAUSE OF RAIN. 



There is one topic of conversation in this country which appears 

 never to lose its interest. Every body can say something upon it, and 

 it generally takes precedence of every thing else we mean, of course, 

 the weather. In a country like this, where it is subject to such sudden 

 changes, it is rather surprising so many vague and incorrect opinions 

 should exist respecting it. One person considers the influence of the 

 moon the grand power which regulates the state of the weather ; another 

 is equally confident that all its changes are occasioned by the wind, and 

 so on. Yet very few can tell why so apparently simple a phenomena as 

 rains occurs. The fact is, "doctors differ" considerably on this 

 subject, and numberless theories have been propounded to explain it. 

 The most probable, we think, hasbeen proposed by Dr. Hutton, which 

 may be explained in the following manner: 



If we leave a little water in an open vessel, we shall find, at the end of 

 that period, that the water has dried up; or, in other words, has evapora- 

 ted. To explain the cause of this, many reasons have been assigned ; but 

 it is unnecessary to enter upon a consideration of them at present. It is 



