WHICH RAINUKOPS AND HAILSTONES ARE FORMED. 49 



larger particles, which will move with greater velocity and, 

 more quickly overtaking the particles in front of them, will 

 add to their size at an increasing rate. 



Under such circumstances, therefore, the cloud would 

 be converted into rain or hail, according as the particles 

 were water or ice. 



The size of the drops from such a cloud would depend 

 simply on the quantity of water suspended in the space 

 swept through by the drop in its descent — that is to say, on 

 the density and thickness of the cloud below the point 

 from which the drop started. 



My object in this paper is to suggest that this is the 

 actual way in which raindrops and hailstones are formed. 

 I was first led to this conclusion from observing closely 

 the structure of ordinary hailstones. 



Although to the casual observer hailstones may appear 

 to have no particular shape except that of more or less 

 imperfect spheres, on closer inspection they are seen all 

 to partake more or less of a conical form with a rounded 

 base like a sector of a sphere. 



Kg. I. 



Perfect Hailstone. 



In texture they have the appearance of an aggregation 



SER. III. VOL. VI. E 



