140 ON THE STORM EXPERIENCED THROUGHOUT THE UNITED STATES 



before the change; though, perhaps, the reverse was the case at New York 

 City, and throughout New England. 



I have now presented the most important facts which I have been able to 

 collect respecting the storm in question. Its principal characteristics were as 

 follow : — After a cold and clear interval, with barometer high, the wind com- 

 menced blowing from the south. The barometer fell rapidly, the thermometer 

 rose — rain descended in abundance. The wind veered suddenly to north-west, 

 and blew with great violence; the rain is succeeded by hail or snow, which 

 continues but a short time; the barometer rises rapidly; the thermometer sinks 

 as rapidly. These changes are experienced not every where simultaneously, 

 but progressively from west to east. 



Before proceeding to analyze these facts more particularly, it may be well to 

 inquire for the probable limits of the storm . This question is not merely curi- 

 ous, but will be seen to be intimately connected with the rationale of the phe- 

 nomena. By inspecting Plate I., Fig. 1, it will be seen that the oscillation of the 

 barometer was every where quite marked, except at Indian Key. It should 

 be stated that the observations at this place were made with a sympiesometer, 

 an instrument far less satisfactory than the mercurial barometer. Here the 

 range was only a quarter of an inch, and the curve described bears very little 

 resemblance to those at the other stations. I am inclined, however, to consider 

 this slight change of pressure as due to the same causes as the greater oscilla- 

 tion in higher latitudes. No rain fell at this station. This, then, was beyond 

 the limit of rain, and the barometer and thermometer were but slightly affected. 

 In Senate Documents, No. 300, 1838, are given observations of the thermome- 

 ter at Santa Cruz, Latitude 17° 45' N., Longitude 64° 35' W., for December, 

 1836. The mean of observations taken six times a day gave, December 15th, 

 76°.2; 16th, 77°.5; 17th, 78°. 1; 18th, 78°.7; 19th, 77°.9; 20th, 77°.2; 21st, 77°.4; 

 22d, 76°.6; 23d, 75°.2; 24th, 75°.9; 25th, 74°.7; 26th, 75°.0; 27th, 74°.4; 28th, 

 75°.6; 29th, 75°. 1. 



The temperature was exceedingly uniform during this whole period, yet it 

 will be observed there was a slight fall of the thermometer on the 23d. This 

 is about the time that the cold wave which passed over the United States might 

 be expected to be felt there, if felt at all. No other particulars respecting the 

 weather are stated, except the general remark that " frequent small showers 



