B. TERRESTRIAL PHYSICS AND METEOROLOGY. 87 



them from frost, we should in this case also covn* the soil 

 with grass. 19 (7, XIV., 135. 



AQUEOUS VAPOR IX THE ATMOSPHERE. 



The Academy sums up the conclusions of Dr. Hildebrand- 

 son, of ITpsala, in regard to aqueous vapor in the atmosphere, 

 as follows : 1. The permanent gases in the atmosphere do 

 not form independent atmospheres, but have effected a com- 

 plete mutual interpenetration ; as all experiments show that 

 the constitution of the air is the same at all heights. 2. The 

 incessant evaporation and condensation which are in prog- 

 ress render impossible the existence of an independent vapor 

 atmosphere, or of a homogeneous mixture of the vapor with 

 the permanent gases, and must cause the vapor to diminish 

 rapidly with height. 3. It is not allowable to subtract the 

 vapor pressure from the barometer reading to obtain the 

 pressure of dry air. 13 A, Feb. 6, 1875, 145. 



THE NEW ANEMOSCOPE. 



Michelle describes an ingenious anemoscope in which three 

 arrows are used, of which the upper one indicates the direc- 

 tion of the wind at each moment. The second indicates the 

 extreme wind on the right, and the third indicates the ex- 

 treme wind on the left hand. Thus, when one looks at the 

 wind vane, we see not only the wind that now prevails, but 

 the extreme winds on either side that have prevailed since 

 the preceding observation. Bulletin Hebdomadaire,X.VI. J 

 12. 



PERIODICITY OF RAINFALL. 



Governor Rawson, of the island of Barbadoes, whose re- 

 markable studies upon the rainfall of that island have been 

 already noticed, states that it is an error to suppose, as Mr. 

 Meldrum does, that the observed rainfall in Barbadoes in 

 any way really supports Mr. Meldrum's theory that there is 

 a sun-spot period in these meteorological phenomena. He, 

 however, very philosophically adds that, if the conclusions 

 drawn from a wide area and very long periods of observa- 

 tion do support that theory, then the opposite results ob- 

 tained in Barbadoes, although that island is most favorably 

 situated for these observations, only show that no particular 



