ATMOSPHEROLpGY. — SNOW. 43l 



tals, and the axle of a slender prism. Figure 43^ 

 45, 46, and 48, represent this modification of snow- 

 crystal. Figure 46, consists of but one tabular 

 crystal and a prism ; and Figure 45, of three laminae 

 and two prisms. The length of this was one- 

 sixth of an inch ; of the other kind, from one- 

 thirtieth to one-tenth. Some of this extraordinary- 

 figure occurred along with the last-described genus : 

 Of which kinds, principally, a quantity of snow three 

 or four inches in depth, onoe fell on the deck of the 

 ship in which I sailed, in the course of a few hours. 

 The temperature, when this kind of crystal fell, was 

 in one instance 22", and in the other 20'. 



Plates VIII, IX, X, and XI. contain represen- 

 tations of ninety-six different snow-crystals, magni- 

 fied from thirty to about four hundred times. The 

 Italic letter following the number of the figure, 

 refers to the second column of the annexed Table, 

 by which, the state of the atmosphere and weather, 

 when each crystal was observed, may be seen. The 

 fractional number which succeeds the Italic letter, 

 shows the diameter of the crystal in parts of an 

 inch. The largest crystal represented was one- 

 third of an inch diameter ; the smallest one-thirty- 

 fifth. They were all perfect figures. Many in- 

 stances, it may be observed, occur of mutilated and 

 irregular specimens ; some wanting two or three ra- 

 dii, and others having radii of different sizes and 

 shapes. But in low temperatures, the greatest pro- 



