WHICH RAINDROPS AND HAILSTONES ARE FORMED. 51 



Again, on careful examination, it is seen that the ordinary 

 hailstones are denser and firmer towards their bases or 

 spherical sides than near the vertex of the cone, which 

 latter often appears to have broken off in the descent. 

 This also is exactly what would result from the manner of 

 formation described above. 



Fig. 2. 



Broken Hailstone. 



When the particle first starts, it will be moving slowly, 

 and the force with which the particles impinge upon it will 

 be slight and, consequently, its texture loose ; as, however, 

 it grows in size and its velocity increases it will strike the 

 particles it overtakes with greater force, and so drive them 

 into a more compact mass. If the velocity were sufficient, 

 the particles would strike with sufficient force to adhere as 

 solid ice ; and this appears to be the case when the stones 

 become large — as large as a walnut, for instance. 



An idea of the effect of the suspended particles on being 

 overtaken by the stone, may be formed from the action of 

 the particles of sand in Mr. Tilghman's sand-blast, used 

 for cutting glass. The two cases are essentially the same, 

 the only difference being that the hailstone is moving 



e2 



