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Transactions. — Physics. 



west. The continued progress of the cyclone to the south- 

 east brings about the following changes : Ac a pressure in- 

 creases to 29-65. with wind about west-north-west ; at b to 

 29-50, wind south-west ; at c to 29-60, wind about south- 

 south-west ; and finally pressure increases to 29-90 at all three 

 stations, with westerly winds. The wind-changes at b and 

 c have been shown to be in accordance with cyclonic wind- 

 rotation, but at a it has changed in the contrary way. Figs. 1 

 and 3 show that the changes of wind-direction within anti- 

 cyclonic or cyclonic systems depend upon the position of the 

 observer with reference to the storm-track. 



The following table shows the changes of pressure at 

 each station (+ showing increase, — showing decrease) : — 



Register of Pressure-movemrnt (Fig. 6), (Southern Hemisphebe). 



Anticyclone and Cyclone Peessuee Curves at a, b, and c 

 (Southern Hemisphere). 



Ju?6. 



Cyclones approach this country from the north-westward, 



but this route does not always lead them to the same part of 



