STATE HORTICULTURAL SOCIETY. 179 



Farther north, in the artic region, may be found, as a constant 

 or passive element, a low temperature. Without a disturbing 

 cause, this low temperature will hover about its proper latitude. 

 When, however, a low barometer, which is always accompanied 

 by high temperature, arises, a high barometer moves into its 

 wake, thus inducing currents of cold air from the arctic region, 

 with a resultant lower temperature. If this low barometer 

 passes through the central or northern portions of the United 

 States, it is easy to understand why it would not draw a volume 

 of cold air into the southern portion of the country. But Avhen 

 the reverse is the case and the low barometer passes well to the 

 southward, as was true of the storm under consideration, and 

 especially if the low has unusual energy, we may, certainly, ex- 

 pect the whole country to be overspread by a sheet of cold. 



There are natural causes which direct and control the move- 

 ments of such storms, when once inaugurated. If not, their 

 movements would be direct, and they would sweep down upon 

 us of the Central Mississippi Valley from the north rather than 

 from the west or southwest. Hudson Bay and the Lakes, to 

 the north of us, with their stores of summer heat, ward off these 

 storms, pushing them, as it were, to the westward and against 

 the Rockies, where they follow in the lee of the mountains, 

 which turn upward and beyond the reach of interference the 

 warm currents from the Pacific, and, facilitated in their move- 

 ments by the great treeless plains, they reach the track of pre- 

 ceding low barometer. As the low almost invariably move to 

 the northeast, the high, with its cold, naturally follows. Thus 

 we have the phenomenon of cold weather coming to us from 

 the west or northwest. 



ILLUSTRATING THE STORM. 



I will now hurriedly illustrate, by the use of a set of tri-daily 

 Signal Service Charts, the movements of the storm under con- 

 sideration. ,As already stated, this ink-spot on the chart in east- 

 ern Colorado marks the center of the low barometer, at 3 p. m., 

 of Jan. 6th. The dark wavy line across the upper portion of 

 the chart indicates the line of zero temperature at that hour. 

 The almost unchanged position of the zero line in the lake 

 region during the prevalence of this storm, will illustrate the 

 beneficial influence they (the lakes) exert upon the climate, a 

 fact which gives to Michigan and the surrounding territory its 

 just renown as a superior fruit-growing section. Turning to our 

 next chart, which represents a period eight hours later, we find 

 that the center of the low barometer is now near Fort Sill in the 

 Indian Territory, and that the zero line has dropped down from 

 Fort Custer to Denver, while all the Gulf region is basking in a 

 temperature much above the frost point. 



