39 



curved, some of them carrying on tlioir summits small particles 

 or caps of brirk. 



Another plienoniouon occasionally witnessed is " ground ice," 

 formed on pebbles at the bottom of clear ponds or streams, and 

 also on metal gratings, or the mouths of j)ipes drawing a supply 

 of water througli them ; in this case the ice sometimes forms a 

 prolongation of the pipe in a direction contrary to the stream. 

 This is puzzling, as Ave have seen that water on falling below 

 thirty-nine decimal two degrees, ceases to become heavier, and 

 the ice is consequently formed on the surface, but (as suggested 

 by Captain M'l3akiu, in an article in the " Proceedings of the 

 Geological Society for 1878,") we have more tlian one cause 

 operating to bring about these results. As water may be raised 

 above the boiling point in the smooth-surfaced vessel before 

 ebullition takes place, so may water be made to sink to eight or 

 ten degrees below the freezing point before consolidation ensues. 

 Again in the case of certain supersaturated solutions of salts, 

 crystallization does not set in till a solid substance presents 

 itself, and particularly if it be a crystal of the salt in solution 

 when it suddenly commences, and is propagated throughout the 

 whole bulk of liquid. This was demonstrated by solutions of 

 two different salts, the one superimposed on the other, which, by 

 introducing fragments of a similar kind, crystallized at once, the 

 latent heat of the liquid, set free on consolidation taking place, 

 becoming very apparant. It is on account of the heat so set 

 free that a rise of temperature is so generally expected after a 

 fall of snow. 



On a clear frosty night the grass, bushes, and boughs of trees 

 radiate tlicir heat, becoming colder than the surrounding air, so 

 that the particles of moisture in the atmosphere arc frozen on 

 coming in contact with them, and the feathers of frost are always 

 formed to windward, and sometimes two inches in length. Jn 

 these we have, then, cases analagous to the formation of ground 

 ice. The stones by radiating their luat become colder than the 

 surrounding water, and being solid substances, the crystallization 

 of the water takes place on coming in contact with them, and, like 

 the hoar irost, in a direction contrary to tlie current. 



The cause of the form of tlie beautiful frost leaves on the window 

 panes is not easy to describe ; but in nature, go as far as we may, 

 there always remains sonictliing to wonder at and admire. Wc can 

 remember our child-like delight when on some bright winter's 

 morning we saw the frost-forms on tlie glass, and perliaps thouglit 

 that fairies in the night had traced them there upon the panes ; and 

 it is a high instinct of the soul that attributes all that is lovely and 

 beautiful in nature to a spiritual cause, and higlur still to the 

 Divine Hand that has given reason and free will to man, instinct to 

 the animals, life and a i'eeble power to seek the light to the vege- 

 table kingdom, and to the mineral kingdom that molecular force 



