364 



RECORD OF SCIENCE FOR 188? AND 1888. 



maxima are characterized by very low temperature. For tliose iu North 

 America the followiug table gives from twelve years' observations the 

 pressure and the departures of temperature for the stations that showed 

 the highest pressure at the time: 



This shows that the higher the pressure by so much greater is the 

 cold. The maxima of pressure and of cold, however, do not as a rule 

 jccur at the same time and place, but lie on the average 400 miles apart, 

 and the greatest temperature departure ordinarily lies north of the high- 

 est barometer. (This which holds for IS^orth America does not obtain in 

 Europe. — W. K.) The temperature depression at the center is greater 

 when the center lies west of 87<^ VV. longitude than when it lies east 

 thereof; for i)ressures of 30.85 inches the temperature depression is in 

 the first case 28.8o F. (or 16o C.) ; for the second case it is 24^ F. (or 13.3° 

 C). In three-fourths of all the cases in series (a) the thermometer at the 

 center fell below 0° F. (or— 17.8° C). In twelve cases it fell to-3Uo 

 F. (or— 34.5° C). For the maxima of the series (b) for Europe, after 

 excluding the two cases of the ocean, the mean temperature fell to 

 —25,4° C, and the mean for the three winter months fell to— 28,llo C. 

 For the maxima of the series (c), iu so far as they occur over Europe 

 and Asia, the departure from the normal was somewhat less, averaging 

 — 19° F., or— 10.6° C, and the mean temperature was about the same, 

 namely -280 0. 



For the average of all cases, whenever the thermometer at Jenisseisk, 

 between 1870 and 1882, went below— 36° C, the barometer stood 7.8 

 millimeters above its normal value, but only in one of these cases did 

 the pressure exceed 787 millimeters. Therefore, extraordinary low tem- 

 peratures are generally accompanied by high, but seldom by extremely" 

 high, barometric pressures. 



In the ivarmer season of the year the temperature in the center of the 

 maxima is also generally below the normal, but only a little below. 

 For the average of the cases where the pressure iu the United States 

 during 1873 to 1880 exceeds 30.35 inches (or 770.9 millimeters) the tem- 

 perature was 8.3° F.=4.7° C. below the normal, and here also for places 

 west of 87° longitude the depression is greater, i. e., 0.0° C, than for 

 places on the east of that meridian, where it is 3.8° C. 



