DYNAMIC METEOROLOGY. 367 



centers of depression occurred in the neighborhood of the coast than in 

 its central portions, and four regions of greater frequency are especi- 

 ally recognizable ; namely, Southern Greenland, west coast of Iceland, 

 the islands north of Scotland, and the North Cape. This confirms in 

 general the results that Koppen attained and presented graphically 

 for all depressions without considering the depths (Zeitschrift Oester- 

 reichisches Gesellschaft fiir Meteorologie, July, 1882).* 



Of the one hundred and sixteen winter days that show a barometric 

 pressure in Asia below 752 millimeters, fifteen show such depressions 

 simultaneously at many places; so that we have one hundred and 

 thirty-one separate cases that are distributed as follows : Thirty-seven 

 on the eastern coast of Asia and in Japan ; seventy-seven on the western 

 border of Asia, namely, at Ekaterinburg, and seventeen in the interior 

 of Asia, at Akmolinsk, Barnoul, or Jenisseisk. The minima of the first 

 group seem to originate in the Pacific Ocean or on the coast. None of 

 them appear to have come from the interior of the continent, or from a 

 region north of latitude 62°, so that the numerous depressions that pass 

 from west to east over the eastern part of North America seem to find 

 no analogue in Eastern Asia. The minima of the second and third 

 groups api)ear to progress from Northern Europe along a path directed 

 somewhat south and east, and none of them pass eastward over Jen- 

 isseisk, unless perhaps some of them are deviated northeastward be- 

 yond the region occupied by the station. 



The highest isobar in the neighborhood of these depressions was on 

 the average, in series {a) 30.29 inches (769.4 millimeters) on the west 

 side, and 30.35 inches (770.9 millimeters) on the east side; in the series 

 (b) the isobars of 785 millimeters and upwards occurred only twice on 

 the west side, and twice on the east side of the depressions ; the maxima 

 in the neighborhood of the deep minima therefore seldom attain ex- 

 ceptional heights — a confirmation of what is above said for the maxima. 

 The mean distance of the centers of these maxima from those of the de- 

 pressions was in series (a) 2,130 miles on the east side of the depression, 

 and 1,985 miles on the west side. The mean diameter of the depres- 

 sions (namely between the isobars of 7G0 to 770 millimeters) Loomis has 

 determined to be for the depressions of series (a) from the years 1877 to 

 1884, 2,139, but for series (6) 2,365 miles. 



The mean of the temperatures at the centers of such barometric de- 

 pressions as were lower than 737 millimeters, was G^A Fahr.,=3o.6 C, 

 above the normal in the United States for the years 1873 to 1877; but the 

 greatest excess of temperature did not occur here, but about 300 miles 

 farther southerly or easterly, and on the average, for the cases that 

 allowed of a satisfactory determination, amounted to 22^.3 Fahr., or 

 10O.3 0. 



•Journal of the Austrian Meteorological Society, July, 1882. See also the charts 

 compiled by me for Walker's Statistical Atlas of the United States, Washington. Ifc74. 



