THE SMITHSONIAN INSTITUTION. 209 



eastern seaboard States now experienced the southwest streann of" moist 

 and hot air — hotter and moister than it was in the west, because while 

 this moveable current is gradually borne to the east its temperature is 

 higher from having been blowing longer from a warmer quarter — on 

 the same principle that an ordinary soulh wind in summer is warmer 

 the second da}^ it blows than on the first. The temperatures on the 

 east coast are in very striking contrast to what the}^ are on the west of 

 the Mississippi. 



Florida, wind SW., temperature 70°, rainy. 



Savannah, " SE., " 04°, rain3% 



North Carohna, Thornbury, " E., " 60°, rainy. 



Washington, •"' " W., " 48°, rainy. 



New York, " WNE., " 53°, rainy. 



Maine, Steuben, " SW. , *" 54°, rainy. 



The weather remained moist and warm on the 13th in the Atlantic 

 States, but the cold air was rapidly advancing from the northwest. By 

 the morning of the 14th it had swept the whole of the southwest cur- 

 rent into the Atlantic and brought cold and clear weather. In Florida 

 the temperature of 70° on the morning of the 12th was changed to the 

 freezing by the 14th ; fi-osts also occurred on the same day m Georgia, 

 South Carolina, North Carolina, Virginia, Pennsylvania, and New York. 

 It is worthy of observation that at the very time the northwest wind 

 was making its cold felt from Florida to New York, the south wind, or 

 a modification of it, had already set in over Texas, and raised the tem- 

 perature 15°, and its influence was afterwards also ftdt as far north 

 as St. Louis, in Missouri. This was merely the first stage of prepa- 

 ration f(jr another atmospheric disturbance which was to run a similar 

 course. 



Striking changes in the temperature of the weather are produced in 

 autumn by the colder wind from the west descending and bearing the 

 moister stream before it; when this hot stream is extended along the 

 Atlantic coast it in all probability becomes the vehicle of the hurricanes 

 which proceed from the West Indian islands. A severe hurricane, 

 having its course along the Florida coast, desolated the rice grounds on 

 the Charles and Savannah rivers on the 8th Septemlier last; but a thun- 

 der storm, extending over the greater portion of the northern States, 

 began on the 6th and travelled from northwest to southeast, causing a 

 great atmospheric disturbance and lowering of the temperature. 



We have only space to say a few words on the barometer duriag 

 the storm of the 12th. Though rain and snow fell over an immense 

 area that day, and the wind blew with great force in the Atlantic S^^ates, 

 still the barometer was above the mean in the morning from Maine, in 

 the east, to Wisconsin, in the west- In this section it is probable that 

 the northwest current, overlying the whole storm, did not sweep away 

 the ascending moist currents with sufficient rapidity, and hence the ac- 

 cumulati(m of air causing the barometer to rise bef()re storms on the east 

 coast. The Alleghany range must, so fiir, favor this accumulation by 

 retarding or hindering the freer action of the winds from the west. 

 When the air has a high temperature in summer, the increased pressure 

 before storms is, I believe, not so much observed. In this storm, also, 

 Mis. Due. 24 14 



