532 SCIENTIFIC RECORD FOR 1883. 



atmospheric electricity; he allows the condensation of vapor by three 

 methods, namely, thermo dynamic cooling, by mixture of cold and warm 

 air, and by radiation, to be of equal importance considering the various 

 circumstances under which these thin clouds are formed. His views 

 are elaborated with skill and corroborated by reference to actual obser- 

 vations. (Z. 0. G. M., xvm, pp. 57-81.) 



Hann has collected the records of diurnal periodicity of rainfall at 

 several European stations. Confining ourselves especially to the rain- 

 fall, but giving a little weight to the snowfall, the records of which are 

 so much more difficult and uncertain, Hann finds in general an after- 

 noon maximum between 2 and 4 p. m., and a night maximum between 

 2 and 4 a. m. At some stations a third maximum between 10 p. m. and 

 midnight, and at one, Vienna, the third maximum between 8 and 10 a. 

 m. At one station, Bern, the afternoon (2 to 4 p. m.) maximum does 

 not occur, but in its place a decided evening maximum between 10 jud 

 11 p. m. (Z. 0. G. M., xvil, p. 53.) 



Sprung recommends the more detailed study of rainfall in connection 

 with the movement of barometric depressions as theoretical conMdera- 

 tions indicate the great relative importance of these two subjects. To 

 this end continuous records must be made of rain, the same as tempera- 

 ture and pressure; he recommends that Nipher's rain-gauge be estab 

 lished upon the roof, the snow caught therein being warmed by the hot 

 air ascending through a surrounding pipe, and the rain or melted snow 

 conducted into the measuring apparatus in the room below. The ar- 

 rangements for measuring and recording may be devised to suit the. 

 observer's ingenuity, but Sprung recommends a method of weighing and 

 recording similar to that adopted by him for the pressure, temperature, 

 and moisture, which methods have proven remarkably satisfactory. 

 (Z. 0. G. M., xvii, p. 140.) 



Dr. A. Augustin contributes to the study of th e daily periodicity of 

 raiufall some items additional to those collected by Hann. He finds 

 for Castelton Moor aud Greenwich three maxima and three minima of 

 quantity but only two of frequency. For New York three maxima and 

 minima exist both in respect to quantity and frequency. In all three 

 stations during the colder portions of the year the morning and after- 

 noon maxima occur closer together than during the warmer portion 

 of the year. (Z. 0. G. M., xvii, p. 235.) 



Dr. F. Augustin has investigated the daily period in raiufall at Prague 

 based ou twenty years' observation ; he finds as above three maxima 

 aud three minima for both frequency and quantity. The intensity of 

 rain, namely, the quantity per minute aud the probability of rain at any 

 minute, has the same periods as the quantity and frequencj^. (Z. 0. 

 G. ilf., XVII, p. 243.) 



Billwiller, from a study of the raiufall in Switzerland iu the autumu of 

 1881, concluded that this season, as also that of August, 1880, studied 

 by Hann, and other cases, shows " that in fact the advance of a baroine- 



