METEOROLOGY. 345 



systematically from in June and July uj^ to 31 or 32 in December and 

 January. {Z. 0. 0. M., xix, p. 393.) 



289. Prof. M.Dechevrens has published a monograph on the typhoons 

 of July and August, 1882, wherein he traces the history of the whole 

 course of several typhoons along the coast of Asia. {Nature, xxx, p. 

 388.) 



290. W.Koppen, in reference to the change with altitude of the position 

 of the center or axis of lowest pressure, sums up his conclusions as fol- 

 lows : The center is at high altitudes pushed towards that side which is 

 colder; therefore, in general, towards the left and backwards; on account 

 of the rapid diminution of temperature towards the east in winter in 

 Europe the exterior isobars of the depression extend especially toward 

 the east, therefore more or less forwards, so that if the position of a cen- 

 ter were in general determined by these isobars a shoving towards the 

 front would apparently exist. The ordinary expression " axis of the 

 whirl is inclined forwards or backwards," which is also used by Clem- 

 ent Ley, leads to misunderstanding. A simple mathematical axis for 

 the whole whirl never exists in our great cyclones ; these must stand 

 perpendicularly on the plane of rotation, and in fact many authors in 

 early and recent times, in speaking of the inclination of the axis of the 

 whirl, have assumed a corresponding inclination of the plane of rota- 

 tion. In truth, however, in the case of a cyclone we are dealing with a 

 superposition of very thin nearly horizontal disks whose vertical axes 

 of rotation do not coincide, but each of which is shoved a little toward 

 the colder side as compared with the one lying immediately below. 

 (D. M. Z., I, p. 1G8.) 



291. Dr. C. Lang, of Munich, contributes a long review of Ferrari's 

 study of thunder-storms in Italy. The observation of thunderstorms 

 has been conducted in Italy since 1870 in very much the same manner 

 as it has been for a long time in France and Scandinavia. Ferrari's 

 monograph is divided into two sections; First, the observations; sec- 

 ond, climatological study; third, a dynamic study. The greatest fre- 

 quency of thunder-storms per square myriameter is in Upper and Cen- 

 tral Italy, whence it diminishes rapidly towards the south, being most 

 frequent in a band nearer the east coast of the peninsula ; the region 

 of least frequency is the whole west coast. This geographical distribu- 

 tion, however, may be somewhat aflected by the geographical distribu- 

 tion of observers, which are also fewest on the west coast, and for whose 

 distribution Ferrari has made an approximate correction. The mouth 

 of greatest frequency is July for Korthern Italy, but the epoch is de- 

 layed as we proceed southward until it becomes August and Septeniber 

 for southern stations. The annual frequency of hail shows no strongly 

 marked features; the neighborhood of the Po has a slight immunity, 

 and the frequency increases northward, but again diminishes close to 

 the foot hills of the Alps. The frequency of ordinary thunder-storms 

 is as usual greatest between noon and C p. m., which quarter of the day 



