1373.] ^*" [Chase. 



years' additional systematic observations, The results of such study seem 

 to me to be important enough to justify others in entering on a similar 

 examination, and I hope the investigation may interest a sufficient num- 

 ber of inquirers to successfully eliminate any influence of personal bias, 

 and to establish new and valuable meteorological laws. 



My weather maps are all of the morning issue, exhibiting the daily of- 

 ficial returns of thermometer, barometer, wind, cloud, rain, and snow, at 

 7.35, A. M., Washington mean time. In order to estimate the compara- 

 tive frequency of cyclonic and anti-cyclonic stonns, I first arranged, in 

 respective columns, such as belonged unmistakably to either class. 

 When it was impossible to determine the character of the current, I 

 counted all that were at and below the barometric mean, as cyclonic ; all 

 that were near the crest of the barometric wave, as anti-cyclonic ; all 

 that were still left in doubt, as adding equal weight to each column. 

 This classification, based on Ferrer s well known-principles, gave "the 

 benefit of the doubt" in all instances to the cyclonic theory, and, if it is 

 chargeable with partiality in either direction, I hope the partiality will 

 prove to be towards the views which are in opposition to my preconceived 

 opinions. 



The number of observations is probably insufficient, and the extent of 

 the comparison too limited to justify any very general conclusions, but 

 there appears to be sufficient consistency in the results to render it proba- 

 ble, that even after storms are well developed and considerable precipita- 

 tion has taken place, the currents continue anti-cyclonic in proportions 

 varying from one-fifth to more than two-fifths of the whole number of ob- 

 servations, the proportion being greater in winter than in summer. The 

 following table exhibits the number of morning rains (R) and snows (S) 

 classed as cyclonic (C), and anticyclonic (A), together with the normal 

 percentages of each, as determined by a simple smoothing of the result- 

 ing curves : 



Classification of American Storms. 



Observed. Normals. 



CK A CS A % C R A CSa' 



January 30 14 48 33 67 33 61 39 



February 38 16 39 33 70 30 62 38 



March 35 11 47 16 70 30 68 32 



April 20 14 8 4 69 31 76 24 



May 31 10 4 70 30 78 22 



June 23 8 71 29 



July 18 10 71 29 



August 21 6 73 27 



September 23 9 73 27 



October 24 8 3 2 71 29 72 28 



November 39 21 37 20 67 33 66 34 



December 30 21 46 25 64 36 62 38 



Winter 201 99 185 115 67 33 62 38 



Spring 209 91 222 78 70 30 74 26 



Summer 215 85 72 28 



Autumn 211 89 138 62 70 30 69 31 



Year 836 364 545 255 70 30 68 32 



A. p. S. — VOL. XIII. 2f 



