It has been observed in the south-east of England that the barometer has
generally passed a maximum on or about the 3rd of every month, and this
has been so frequently the case as to form the rule rather than the
exception. The same fact during a more limited period has been observed
at Toronto. With especial reference to this subject the three-hourly
series of observations may be resorted to in all localities, but
especially north of the 40th parallel in the northern hemisphere. They
should be commenced at midnight immediately preceding the 1st and
continued to midnight succeeding the 5th.




CHAPTER IV.

PRACTICAL DIRECTIONS FOR AVOIDING THE CENTRES OF ROTATING
STORMS.


Figures 1 and 2, enlarged and printed on narrow rings of stiff
cardboard, are employed for this purpose. The letters outside the thick
circle are intended to distinguish the points of the compass, and in use
should always coincide with those points on the chart. The letters
within the thick circle indicate the direction of the wind in a
hurricane, the whirl being shown by the arrows between the letters. In
the northern hemisphere the direction of the whirl is always contrary to
that in which the hands of a watch move, and in the southern coincident
thereto. The graduation is intended to assist the mariner in
ascertaining the bearing of the centre of a storm from his ship.