Edwin. — On the Principle of New Zealand Weather Forecast. 47 



mediately preceding it ; in the space intermediate between the areas the 

 weather is nearly always fine with light winds, whose direction mainly 

 depends upon whether the place is nearest to the approaching or departing 

 depression. 



In this example the space between the two is shown to be 29'90, and 

 thus the line of 30-0 becomes an isobarometrical binding-contour or binding- 

 line of one or more such areas as have just passed, and if pressure again 

 diminishes, the re-appearance of all the contours above 30-0 will be delayed, 

 and therefore they are also binding-lines; but as experience shows that pres- 

 sures above 30-10 are of much less frequent occurrence at the southern 

 stations than at others, it will be more convenient to consider 30-10 as the 

 first binding-hne, 30-0 the second, and so on, should the systems be suffici- 

 ently complex to necessitate the number of these lines being increased. 



Eeferring again to the diagram, it will be found that while the wind con- 

 tinues from the southward upon the eastern and western coast, it has already 

 backed at the Bluff, and as the diagram moves along it shows pressure 

 diminishing rapidly in the south, and within twelve hours it has fallen to 

 29-75 at Bluff, wind north, and a second northerly gale has now commenced, 

 accompanied by a heavy sea upon the western coast ; but at Wellington the 

 barometer has risen to 29-95, wind still from the southward, while at Hoki- 

 anga it has risen to 30-28, wind W.S.W. The fifth day shows a further 

 fall to 29-55 at Bluff, and a corresponding movement has evidently taken 

 place over a wide area, resulting in a heavy northerly gale ; the barometer 

 has now risen to 30-0 at Welhngton, the highest point reached being about 

 30*02, the wind soon afterwards backing to N.W., while but little change has 

 taken place at Hokianga; within the next txvelve hours the barometer falls 

 to 29-45 at Bluff, and it also rises to 29-50, wind as before, veering south- 

 ward as pressure is increased, and causing a heavy sea on the western coast ; 

 at Wellington the barometer falls to 29-86, and although this is only a fall 

 of 16/100 it is accompanied by a heavy northerly gale at this station ; at 

 Hokianga the barometer falls to 30-22, wind W.N.W. 



On the sixth day a further increase has taken place in the south, the 

 reading at Bluff being 29-72 ; a hard southerly gale is now experienced 

 throughout the South Island, but pressm-e at Wellington has diminished to 

 29-78, and at Hokianga to 30-18, the wind having now changed south of 

 west at both places ; tivelve hours later the barometer has risen to 29-90 at 

 Bluff, and the gale has now decreased at stations south of Lyttelton, but is 

 blowing hard between that place and Napier, barometer reading 29-82 at 

 Wellington, rising ; and 30-15 at Hokianga, where it has fallen slightly, 

 the wind being a gale from the southward of west at both places, and the 

 sea is now heavy between Kaikoura and Castlepomt. 



