2 7 8 THE POPULAR SCIENCE MONTHLY 



Nevertheless, their use has not spread since they were proposed, two or 

 three years ago. It is to be hoped that they are not destined to share 

 the oblivion of some analogous terms relating to atmospheric pressure 

 proposed about forty years ago by Prestel ; viz., " pleiobar," " mesobar " 

 and " meiobar." 



Purely English terminology has received some useful amendments 

 at the hands of Dr. Hugh Robert Mill, who in this respect is carrying 

 on the worthv traditions of " British Bainfall." Thus he has balanced 



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Symons's terminology of droughts — the "absolute" and the "partial" 

 drought — by introducing the term " rain spell " for a period of more 

 than 14 successive days with rain. This expression, however, like the 

 term "rain day," is one that would need to be redefined in other coun- 

 tries. Dr. Mill has rendered an even more useful service to precise 

 terminology by distinguishing between the words " mean," " average " 

 and "general." He speaks, for example, of the mean temperature at 

 Camden Square during the month of June, 1900 ; the average tempera- 

 ture at the same place in June during a ten-year period; the general 

 rainfall over the whole county of London in May, 1910, and the average 

 general rainfall over the same region for a term of years. 



British meteorologists have also succeeded in establishing a work- 

 ing terminology in English for the various deposits of frozen moisture 

 that have occasioned so much fruitless discussion at international 

 meteorological meetings. The Meteorological Office now applies the 

 term "rime" to the rough deposits due to fog, and "glazed frost" to 

 the transparent smooth coating usually caused by rain which freezes as 

 it reaches terrestrial objects. The ambiguous expression "silver thaw" 

 has been discarded in British meteorology. 



The endless subject of cloud terminology and nomenclature can not 

 be discussed in this paper; but I wish to call attention to one term in 

 this connection recently introduced by M. Besson. This is the name 

 "nephometer" for an instrument used in measuring the amount of 

 cloudiness, as distinguished from the familiar " nephoscope," by which 

 we observe the positions and movements of individual clouds. 



German meteorologists have lately introduced the all-Greek names 

 " chionometer " and " chionograph," and the hybrid "nivometer," for 

 the instruments used in measuring snow. Although these terms will 

 hardly displace "snow-gage" in English, we shall probably find it con- 

 venient to use their derivatives ; e. g., " nivometric " ; just as we use 

 " pluviometric," though we generally avoid " pluviometer." 



The name " ceraunograph " applied by Odenbach in 1891 to his 

 variety of the thunderstorm-recorder now seems destined to become the 

 generic and international designation for the numerous instruments of 

 this class. Particular forms have been known as "thunderstorm-re- 

 corders," "lightning-recorders," " brontometers," " brontographs," 

 " ceraunometers," "electroradiographs," etc. " Ceraunophone " will. 



