PROCEEDINGS OF SECTION A. 25 



5.— THE EAST WIND. 



By H. Jacob. 



(Abstract.) 



Au inquiry into its origin and character, in the light of recent 

 observations of the circulation of air in the cavities of the earth. 



It has been found that in certain bores in the Pinnaroo District a 

 current of air flows down into the cavities of the rock overlying the 

 groundwater, and that this flow continues steadily during periods of 

 high atmospheric pressure, sometimes for several days without inter- 

 mission. 



The downward flow ceases when the barometer falls approximately 

 to 30 inches, and during a period of low pressure the current of air is 

 reversed, and flows steadily up from the bowels of the earth, ceasing 

 only when normal pressure is restored. 



Thus a rhythmical vertical circulation of the air in the pores of 

 the earth is seen to accompany the rise and fall of the barometer. 



Indirect evidence has been, obtained of a similar circulation of the 

 air in subterranean cavities in other parts of the continent, notably 

 in the NuUarbor Plains, at the head of the Great Australian Bight. 



The object of the paper is to show that the phenomenon is universal 

 and that the character of the East Wind, which invariably accomj)anies 

 a falling barometer, is mainly due to the vitiating efiect of the air 

 exhaled from beneath the surface of the earth. 



Indirectly, the writer endeavours to show how the habits and 

 customs of the past— and of the present in many places — by polluting 

 the earth have intensified the evil effects of the East Wind. 



6. ON AN EXACT MECHANICAL ANALOGY TO THE COUPLED 

 CIRCUITS USED IN WIRELESS TELEGRAPHY, AND ON 

 A GEOMETRICAL METHOD OF INTERPRETING THE 

 EQUATIONS OF SUCH CIRCUITS. 



Btj Professor Thomas R. Lyle, M.A., Sc.D., F.R.S., University of 



Melbourne. 



1. If a periodic e.m.f. = E acts on a circuit having resistance = i?, 

 inductance = L, and capacity = K, it is well known that the current C 

 produced will satisfy the differential equation— 



where D stands for — 

 dt 



