46 Transactions. — Miscellaneous, 



tenths, and that within the same twelve houi's it rises to 29*64, the wind 

 veering south of west as pressure increases. A southerly gale is now blow- 

 ing over the South Island, and a heavy sea accompanies it at Greymouth 

 and Hokitilva ; but the barometer is still falling at Hokianga and Wellington, 

 and we further find that it rises at Hokianga, where its lowest point is 30-25 

 before pressure has at all increased at Wellington, where it faUs to 29'93. 

 On the fourth day the barometer has risen to 29*90 at Blufi", the sea making 

 moderately on the eastern coast ; at Wellington the wind has changed 

 southward, and pressure has decreased to 29-88 ; and at Hokianga the 

 barometer has risen a little. The wind is now from the southward of west 

 throughout the colony, and the low area which has just passed is now shown 

 to the eastward. 



Now, if this cyclonic wind is a true circle, pressure should continue to 

 increase in all parts of the colony until it has returned at all stations to the 

 point from which it commenced to diminish, and the wind should change 

 to eastward of south ; but these conditions are frequently delayed for a 

 considerable time, and it generally happens that the barometer commences 

 to fall again in the south long before it has attained the height necessary to 

 ensure complete cyclonic formation, the deficiency being curiously graduated, 

 the approach to the complete form being most nearly attained in the north 

 and becoming markedly less so in the south. 



To anticipate this falling movement, which is always accompanied by a 

 backing wind, is one of the difficulties of weather forecast; and, as its occm*- 

 rence is a sure sign of more bad weather, it is evident that a warning 

 received after it has taken place is deprived of much of its value in practice. 

 The approach of this backing movement is shown by the tendency of the 

 curves to open out, caused by there being but httle difference of pressure at 

 adjacent stations. It is more readily detected in the southern than in the 

 northern part of the colony, there being a wider land-area in the former case, 

 and it is also accompanied by a decrease of sea on the western coast of the 

 South Island ; unless the new area be of large dimensions, in which case the 

 sea will change northward, even while the barometer is rising ; or, if the 

 depressions are passing more to the southward of us than usual, and are at 

 the same time moving on a north-easterly line, then the sea will continue 

 from the south-west, as if the barometer were about to continue rising. 



Another point of value is humidity, which will usually be found to have 

 decreased as the barometer rises, but not to the extent that the increased 

 pressure would imply, while, in some instances, it will be found that an 

 increase accompanies an increase of pressure ; neither of these movements 

 seems unreasonable, if it can be admitted that the northern winds of one 

 depression can exist in close proximity to the southern winds of the one im- 



