n to their connexion, our great
object here will be to endeavour to mark out such a line of observation
as appears most capable of throwing light, not only on the most
important desiderata as connected with storms, but also their connexion
or non-connexion with atmospheric waves. We shall accordingly
arrange this portion of the instructions under the following
heads:--_Desiderata_; _Localities_; _Margins_; _Preceding and Succeeding
Accumulations of Pressure._

_Desiderata._--The most important desiderata appertaining to the subject
of storms, are certainly their origin and termination. Of these initial
and terminal points in the course of great storms we absolutely know
nothing, unless _the white appearance of a round form_ observed by Mr.
Seymour on board the Judith and Esther, in lat. 17 deg. 19' north and long.
52 deg. 10' west (see Col. Reid's 'Law of Storms,' 1st edit. p. 65), may be
regarded as the commencement of the Antigua hurricane of August 2, 1837.
This vessel was the most eastern of those from which observations had
been obtained; and it is the absence of contemporaneous observations to
the eastward of the 50th meridian that leaves the question as to the
origin of the West Indian revolving storms unsolved. Not one of Mr.
Redfield's storm routes extends eastward of the 50th meridian; this at
once marks out, so far as storms are concerned, the entire space
included between the 20th and 50th meridians, the equator and the 60th
parallel, as a most suitable area for observations, under particular
circumstances hereafter to be noticed, with especial reference either to
the commencement or termination of storms, or the prolongation of Mr.
Redfield's storm paths.

_Localities._--The three principal localities of storms are as
follows:--I. The western portion of the basin of the North Atlantic; II.
The China Sea and Bay of Bengal; and III. The Indian Ocean, more
particularly in the neighbourhood of Mauritius. The first two have
already been marked out as areas for the three-hourly observations; to
the latter, the remark as to extra observations under the head of
Desiderata will apply.

_Margins._--Mr. Redfield has shown that on some occasions storms have
been preceded by an unusual pressure of the atmosphere; the barometer
has stood remarkably _high_, and it has hence been inferred that there
has existed _around_ the gale an accumulation of air forming a margin;
barometers placed under this margin indicating a mu