THE SMITHSONIAN INSTITUTION. 211 



undivided current in winter, the weather is intensely cold in England. 

 Coming over ranges of mountains and a long stretch of land, it is some- 

 thing like the west wind of the United States — as long as it is continu- 

 ous, the cold is unabated; when the same wind prevails in summer the 

 whole country is parched with drought ; but v/hen the surface east wind 

 is overlaid by a current from the southwest, then the east wind becomes 

 excessively wet and disagreeable. An east wind in Scotland is very 

 rarely stormy either in summer or autumn, unless it has an upper cur- 

 rent from the southwest. This upper current from the ocean supplies 

 the moisture which is precipitated by the lower wind. After long 

 periods of dry summer weather in Scotland, the barometer begins to 

 fall several days before the rain storm comes on. The first symptoms 

 of change are, usually, cirrous clouds floating in the upper regions of the 

 atmosphere, and indicating a greater saturation going on above. Cu- 

 mulous clouds at length form, and drift from southwest to northeast, often 

 directly against the lower wind. A thunder storm begins the rainy 

 season ; and so long as the upper current continues, the east wind is 

 rainy or moist. 



The fall of the barometer, it would appear, arises from a warm and 

 moist stratum of air taking the place of a colder one above ; on the 

 same principle as a moister and warmer one depresses the barometer 

 in the Mississippi valley. For this reason the barometer is very much 

 consulted as an indicator of changes in the weather in Great Britain. 



The summer rain-storms often extend over a large area in Europe. 

 I have traced the northeast wind blowing, as a broad current, from the 

 Alps to the south of Scotland, while rain was falling over the greater 

 part of this space. 



The winter storms are also regulated by the same principles. When 

 there is no upper current from the west, the east wind remains dry and 

 cold ; but when the southwest upper current begins to blow, it becomes 

 wet and stormy, and almost all the great falls of snow in winter take 

 place under these conditions. The barometer does not give as long a 

 warning of an approaching storm in winter as it does in summer, but 

 there is invariably a fall in the mercury before the storm comes on. To 

 illustrate the character of our winter storms the following example is 

 given : 



During the month of December, 1853, the wind was, in general, east 

 in England, not only at the surface of the ground but at great eleva- 

 tions in the atmosphere. The barometer was high and steady for that 

 winter month. The rivers from the north to the south of the island 

 were more ice-bound than the}' had been for 15 3'ears. 



On the 1st of January, 1854, the weather was very cold over Great 

 Britain, as well as the northwest of Europe. There was no storm that 

 day, and the temperature of the air did not differ much from Sandwich, 

 in Orkney, to Brussels, in Belgium. 



Temperature. 

 Wind. Max. Min. 



Sandwich Manse, Orkney NW 28^ 28° 



Keleoliess, Fife NW 34° 12° 



Highfield, Nottingham WNW 32=' 14° 



Liverpool, Lancashire NNW 36° = 27o 



