176 TRANSACTIONS OF THE ILLINOIS 



DEFERRED PAPERS. 



Part of these papers were not read for want of time ; others 

 did not come into the hands of the Secretary in time to appear 

 in their proper places: 



A COLD WAVE ILLUSTRATED; OE, HOW A BLIZZAED 



GETS AMONG US. 



BY W. H. RAG AN, INDIANA. 



It is a wise design of nature that provides for the constant 

 changing and shifting of our atmosphere, without which stag- 

 nation and death would result. There are three principal causes 

 which operate to produce atmospherical disturbances — the rotary 

 motion of the earth on its axis, the daily fluctuations of tem- 

 perature due to the sun's heat, and the varying density, or weight 

 of the earth's atmosphere. The first is constant, and, without 

 the co-operation of one or both of the others, could only produce 

 a regular shifting of the atmosphere with reference to the earth's 

 surface, and that without violence. The second would produce 

 local currents from the land to the sea, or from elevated to low 

 lands, or the reverse, as the alternate conditions of heat and cold 

 would succeed each other, by day or by night. 



The third is, therefore, the great disturbing cause — the unequal 

 weight or the atmosphere in adjacent regions for all important 

 movements of the atmosphere result from differences of pressure. 

 The direction of such movements is from the areas of high 

 towards the areas of low pressure. If it were not for these 

 causes, atmospheric disturbances would be unknown, and the 

 climate of a given place would be almost entirely determined by 

 its altitude and its latitude. 



An area of low pressure, or technically a cyclone, is a mass of 

 air, of hundreds or thousands of miles in diameter, which has a 

 great motion from the right to the left, and towards a common 

 center or point of minimum pressure. It also generally has a 

 progressive motion, and brings to the places over which it passes, 

 clouds, precipitation, changes of temperature, and sometimes 

 violent atmospheric disturbances. This great cyclone, or meteor, 

 with its rushing currents, 'sweeps over the country for miles, 



