SNOW AND ICE 41 



be drawn to other examples of ice crystals, to those in hoar 

 frost, to the ice needles which form on the pavement, and especi- 

 ally to the beautiful patterns to be seen on window panes, these 

 patterns being again due to the tendency of ice to form six-sided 

 crystals. Show also the needles appearing on ponds as these begin 

 to freeze, and their subsequent disappearance as the complete 

 crust of ice forms. The subject may be further illustrated by 

 dissolving common salt or washing soda in water, and allowing 

 the solution to slowly evaporate on a plate in the warm room. 



As snowstorms are relatively infrequent in our normal winters, 

 there is no difficulty in obtaining an exact measurement of the 

 amount of snow which falls throughout the winter period. That 

 is, the fall on each occasion should be measured, and at the end of 

 the winter the totals should be added up, and the reckoning of an 

 inch of rain to a foot of snow used to show how small a part of our 

 total precipitation falls as snow. In the preliminary lessons the 

 teacher has already emphasised the fact that Great Britain differs 

 from many other places in the same or lower latitudes in the absence 

 of a continuous winter covering of snow. After observations on a 

 winter's fall have been made, it is a good plan to go back upon this 

 lesson, and by the help of actual figures point out the contrast 

 between our conditions and those which prevail elsewhere. 



Thus in the New England States generally the average snow- 

 fall ranges from 4 to 7 feet. On the southern shore of Lake 

 Superior the winter fall is nearly n feet, while at the point 

 where the Central Pacific Railway crosses the Sierra Nevada the 

 winter fall is 30 feet. Seizing some striking figures of this kind 

 one would in imagination lead the class northward to the region 

 where all precipitation takes the form of snow, and southward 

 where it never occurs, striving always to make the facts real by 

 dwelling on the human side of the facts. Thus the disorganisation 

 of traffic which often follows a sudden heavy snowfall in this country 

 should be compared with the conditions which prevail in countries 

 where a heavy fall is normal, and therefore discounted in advance. 

 The class should, of course, be encouraged to observe for themselves 

 such facts as whether snowploughs are or are not familiar objects 

 in the neighbourhood, for this has an important bearing on the 

 local climate.. If the whole question of transportation considered 



