44 Transactions.— Miscellaneous. 
fall again within a limited area, but continues to rise slowly at places beyond 
those limits, while within them the wind suddenly ‘‘ backs” to the north- 
east, and a second hard northerly gale becomes rapidly developed within 
this area; this second fall usually reaches the same point as its predecessor, 
the barometer then makes a second rapid increase which extends to the 
whole colony, and a heavy gale from the southward is generally experienced, 
this being the second southerly gale within the limited area already men- 
tioned ; the lowest pressure in these gales generally ranges between 28-90 
and 28:50, and the total fall at the southern extreme of the colony amounts 
to about 1:25 inches. 
These areas usually travel about east by north, and the general, or I 
believe it may be termed the normal routes of the gales which approach 
New Zealand, are between W.S.W. and S.S.W., moving to the opposite 
quarter; but after a considerable period, generally not less than six months, 
a depression comes in from the north-west, after whose passage the normal 
route is resumed, and this change takes place, on some occasions, with such 
promptitude that it is difficult to issue warnings in advance of it. Compar- 
atively few of these north-west areas have come under investigation since 
the principles of Forecast now in use have been fully in operation, but 
there have been several of them, and there is no doubt that they, at times, 
are of the class here described as double-centred. The depressions which 
approach from the west of south are systems of multiple areas, some of 
which are of intricate construction, and during their passage the wind 
changes from north-east to north and west, veering as we term it in New 
Zealand, but backing according to meteorological law; and, as each suc- 
cessive area approaches us, the wind moves from west of south to north of 
west, which we term backing, but which is a veering movement according 
to meteorological law. From these remarks it will be seen that the wind- 
change in this colony is the same as in Great Britain, but during the 
passage of areas from north-west the wind obeys the laws for the Southern 
Hemisphere. 
An interesting subject for investigation is offered by the atmospheric 
circulation of the temperate zones; for in England and America the same 
routes seem to hold good as in New Zealand, the depressions travelling 
from south of west to the north of east, and being at times interrupted by 
the passage of an area from north-west, and it thus appears that northern 
countries are mainly supplied from a tropical direction, the balance being 
restored from a polar quarter, whereas our supply is generally derived from 
the polar side, and recouped, as it were, from the tropic. 
A marked feature of this Forecast are binding isobaric contours, or 
binding-lines, which enclose the secondary and minor areas, and which are 
