306 SUPPLEMENTARY OBSERVATIONS ON STORM OF DECEMBER 20, 1836. 



Cincinnati. Latitude 39° 6' N.; Longitude 84° 27' TV. 





Thermometer. 



Barometer. 



Wind. 



Rain. 



Weather. 



Remarks. 



Sunrise. ,2, P. M. 



9, P. M. 



5, A. M. 



1, p. M. 



9, P. M. 1 A. M. 



p. M. 



Sunrise. 



2, P. M. 



9, P. M. 



19 

 20 

 21 

 22 



8 



41 



60 



3 



43 

 43 

 11 

 25 



36 



49 



8 



20 



29.56 

 .23 

 .43 



.82 



29,53 



28.97 



29.54 



.64 



29.51 



28.71 



29.76 



.47 



s. w. 



E. 

 W. 



s. 



s. w. 



E. 

 N.W. 



S.E. 



1.00 



clear 

 cloudy 

 clear 

 clear 



hazy 

 rainy 

 clear 

 hazy 



variable 

 cloudy 

 clear 

 hazy 



f Wetdayjsud- 

 i den change; 

 ; strong East 

 i, wind. 

 Strong wind. 



From these observations it appears that at Fort SnelUng the barometer did 

 not begin to rise till about 3, P. M., of the 20th, although the wind had changed 

 to north-west before 9, A. M. This is similar to what I have several times ob- 

 served at Hudson. In the eastern states the barometric minimum coincided, 

 in the present instance, almost exactly with the change of wind, and, in the 

 absence of evidence to the contrary, I had inferred that the same rule was 

 general. It appears, however, not to have been true; for the north-west part 

 of the United States, and the lines of barometric minimum in this vicinity, 

 should be represented with greater curvature than they are given on my chart. 

 The atmospheric wave, then, in latitude 45°, travelled with nearly twice the 

 velocity it did in latitude 30°. The entire range of the barometer at Fort 

 Snelling was .67 inch, about half what it was in longitude 72°, on the same 

 parallel. At the same rate, the oscillation would be reduced to about one-third 

 of an inch in the neighbourhood of the Rocky Mountains. 



