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XXIV. 



SOME OBSERVATIONS OF DEW AT KIMBERLET. 

 By J. R. SUTTON, M.A., Sc.D. 



[communicated by peofessor w. beown, b.sc] 



[Read November 23. Ordered for Publication Decembek 7, 1909. Published January 15, 1910.] 



British meteorologists of late years, in discussing the theory of dew and 

 its formation, have shown some disposition to abandon the teachings of 

 Wells in favour of those of Aristotle. A few quotations (out of many that 

 might be made) from the writings of well-known authors will serve to 

 illustrate this backsliding : — 



1. " It is observed that dew is never copiously deposited in situations 

 much screened from the open sky, and not at all in a cloudy night ; but if the 

 clouds withdraw even for a few minutes, and leave a clear opening, a 

 deposition of dew presently begins." ^ 



2. Dew "is never deposited in cloudy weather; and so strict is its 

 connexion with a clear sky that its deposition is immediately suspended 

 whenever any considerable cloud passes the zenith of the place of obser- 

 vation." ^ 



3. " Dew is deposited over the Earth's surface on comparatively clear and 

 calm nights. . . . Dew is not deposited in cloudy weather, because clouds 

 obstruct the escape of heat by radiation." ' 



4. " It is known to everyone that dew does not appear on a cloudy 

 night." * 



5. " Dew may be defined as moisture deposited when visible cloud is 



Statements such as these are the more remarkable in view of the fact that 

 on the soil of Great Britain have been made the observations which, more 

 than any other, have put the theory of dew upon a rational basis. It is not 



1 J. Hersohel, "Preliminary Discourse on the Study of Natural Philosophy," 1831, p. 162. 

 ^J. Herschel, " Meteorology," 1862, Art. 91. The italics are Herschel's in both quotations. 



2 A. Buohan, in Art. " Meteorology," Enctj. Brit., 1878. 

 ^R. H. Scott, "Elementary Meteorology," 1893, p. 117. 



^ W. Allingham, " A Manual of Marine Meteorology," 1900, p. 149. 



