PHYSICS OF THE GLOBE. 79 



as they rush through the air. The structure of hailstones, 

 especially conical ones, shows that they have been formed by 

 accretions on the lower side or base. 



Professor Fritz, of Zurich, has published a characteris- 

 tically thorough memoir on the geographical distribution 

 of hail. 



The classification of hailstones according to their external 

 characteristics has been attempted in considerable detail by 

 Prestel. 



The formation of hailstones is considerably elucidated in 

 a short article by Flogel, of Bramstadt, who, in some re- 

 marks upon a memoir by Reynolds, explains that the obser- 

 vations made by himself, and in 1791 by Wilke, and in 1844 by 

 Schumacher, all point to the conclusion that a crystal of snow 

 or ice, having once been formed at a considerable altitude, 

 and descending rapidly, grows in size only by additions to 

 its lower side ; if, therefore, its original shape allows of it, it 

 will keep the same end always uppermost, and will grow into 

 a conical mass of ice, which will on its exterior be marked 

 by ridges or striae corresponding to the angles of the orig- 

 inal crystal. In this connection we call attention to a fall 

 of remarkably well-developed conical hailstones that is de- 

 scribed in the Weather Review for April, of the Army Signal 

 Service. 



The hailstorm of April 4, 1877, is described by Godefroy 

 in the Comptes Hendies, with numerous illustrations. Con- 

 ical stones similar to those above described fell abundantly. 

 The question as to whether hailstones are to be considered 

 as built up from the sphere or the cone as the nucleus is set- 

 tled by K.Fritsch, whose great experience entitles him to say 

 that both are equally common. 



The result of all the recent investigations into the diurnal 

 change of temperature and moisture with altitude is thus 

 summed up by Rubensen, of Upsala : The air at the earth's 

 surface is, by the foil of its temperature, quickly brought to 

 the point of saturation. From this instant on, a deposit of dew 

 and a diminishing absolute humidity closely follows every 

 lowering of the temperature. This diminution appears soon 

 to reach a constant maximum, at which it probably remains 

 for some time. Meanwhile, either through diffusion or by 

 the descending current of air, new aqueous vapor is conduct- 



