362 RECORD OF SCIENCE FOR 1887 AND 1888. 



ber of separate occasions on which high maxima occur, each one heiug 

 separated from the other by intervening times of low pressure; the 

 second number [in brackets] gives the number of charts on which they 

 occur. With respect to these numbers it is necessary' to remember that 

 for the United States (series a) there are three charts daily, but for 

 Europe and the Atlantic Ocean (series h) two, and for the northern 

 hemisphere one each day (series c). 



(a) Uuited States aud Canada. -1[3] 

 {b) Europe and Atlantic Ocean. 2[4] 

 (c) Northern hemisphere 1[1] 



In the other months of the year such high barometric readings do not 

 occur. 



As concerns the geographical distribution over the surface of the earth, 

 the maxima occurred as follows : 



Series {a). — Eighty-two per cent, west of 90° longitude (west of Green- 

 wich), and the greater part north of 46° north latitude. 



Series (b). — Three-fourths were in Asia and only two on the Atlantic 

 Ocean.* 



Series (c). — Of these eighty-one charts, seventy-four show the maxi- 

 mum over Europe and Asia, six over North America, and one on the 

 ocean west of Ireland. The station with the highest pressure occurred 

 in Europe or Asia, always between latitude 50° and G0° north, with one 

 exception, when it was at Taschkent; in thirty two cases it was at 

 Jenisseisk (latitude o8°.5 north); in nine cases at Barnaul (53° north), 

 and in seven cases at Kertschiusk (51° north), and the other seven at 

 Semipalatinsk (50°.5 north). Within Europe proper such extreme 

 maxima were observed only in European Eussia, and the centers oc- 

 curred either at Wjatka, Kazan, Moscow, or Warsaw, the two latter 

 only once each. Such high pressures occur very decidedly only in the 

 centers of the continent and in the colder seasons of the year. 



For such of the areas of high pressure as could be followed for many 

 days the following results are given : 



Series {a). — An average movement toward south 40° east, or, if we con- 

 sider only the movement east of the Rocky Mountains, south 57° east, 

 with a velocity of 21 English miles per hour (eight degrees of a great 

 circle per daj ) ; the average movement of the maxima is therefore di- 

 rected more southerly than that of the minima. 



Series (6). — In fourteen cases of long-continued high areas there were 

 eleven where the last position lay more southerly than the first, and 



* On nineteen of these eighty-two charts, the highest isobar is 790, on five charts 

 it is 795, and on one chart (January 1, 18761 it is 800 millimeters ; ou this day the 

 maximum was at Omsk ; in the year 1877, for which the Hoffmeyer charts were not 

 printed, there occurred a still higher barometer, on December 16, namely, 806.5 as 

 reduced to sea-level, or unreduced 784.5, which is the highest atmospheric pressure 

 that Loomis has found anywhere charted. 



