358 SCIENTIFIC RECORD FOR 1884. 



time in advance we must determine the connection between the local 

 weather and the general circulation over a large part of the earth's sur- 

 face as due to these centers. {Z. 0. G. ili., xix, p. 105.) 



323. [The centers of action, as he calls them, seem to be identical with 

 the large areas of maximum and minimum pressure first marked out by 

 the isobars of Buchan and generally known to meteorologists as conti- 

 uental and oceanic maxima and minima. Teissernc de Bort gives in 

 detail the types of weather peculiar to France for each location, of the 

 surrounding maxima and minima areas, but the assumption running 

 through his essay to the effect that the changes of local weather are 

 directly due to the changes in the pleiobars and meiobars, as they were 

 called by Prestel, seems to us quite unwarranted. This matter is refer- 

 red to in a circular ot the Signal Office, published in June, 1871, "How 

 to use weather majis," and was for several years carefully studied from 

 Teisserenc de Bort's present i)oint of view, but the present writer was 

 forced to the conclusion that some ulterior forces controlled both the 

 local weather and the permanent or subpermanent highs and lows, so 

 that although it is very convenient, for instance, to connect our Atlantic 

 coast weather with the Atlantic area of high pressure between latitudes 

 20 and 30 degrees, yet it is not possible to say that the latter is cause 

 and the other effect.] 



324. H. H. Hildebrandsson has still further investigated the average 

 distribution of meteorological elements, wind, clouds, temperature, rain, 

 haze, or fog, with reference to the isobars ; he divides these latter into five 

 zones, namely, the low center, three intermediate bauds, and the high 

 area. Each of these zones he divides into eight iwrtions according as 

 the gradient therein is directed toward the north, northwest, &c. The 

 examination of six years of weather maps shows that for Upsala and 

 for southern and central Sweden the following generalizations hold 

 good : 



1. The wind niakes a greater angle with the gradient in summer than 

 in winter and within a minimum than within a maximum ; greater at 

 sea than on land ; greater for gradients directed towards the east and 

 least for those towards the west. The strength of the wind is greatest 

 for gradients directed towards the north and least for those towards the 

 west and southwest. 



2. The lower clouds move in directions deviating to the right from 

 the direction of the wind at the earth's surfiice ; the lower clouds move 

 nearly perpendicular to the gradients »r parallel to the tangents of the 

 isobars; for gradients towards the west the lower clouds are inclined 

 more than 90°; that is to say, the air is moving away from the area of 

 low pressure. 



.3. The cirrus clouds move from the minima out towards the maxima; 

 this movement is feeblest near the center of depression and most rapid 

 within the maximum zone; the movement is greater on the advancing 

 side of a depression, or on the western side of a maximum; directly be- 



