{ Triple-reefed
} { topsails, &c.
9. Strong gale } { Close-reefed top-sails
} { and courses.

10. Whole gale or that with which she could scarcely bear
close-reefed main topsail and reefed foresail.
11. Storm or that which reduces her to storm staysails.
12. Hurricane or that which no canvas could withstand.

_Corrections._--As soon after the observations have been made as
circumstances will permit, the reading of the barometer should be
_corrected_ for the relation existing between the capacities of the tube
and cistern (if its construction be such as to require that correction),
and for the capillary action of the tube; and then _reduced_ to the
standard temperature of 32 deg. Fahr., and to the sea-level, if on
shipboard. For the first correction the _neutral point_ should be marked
upon each instrument. It is that particular height which, in its
construction, has been actually measured from the surface of the mercury
in the cistern, and indicated by the scale. In general the mercury will
stand either above or below the neutral point; if _above_, a portion of
the mercury must have left the cistern, and consequently must have
_lowered_ the surface in the cistern: in this case the altitude as
measured by the scale will be _too short--vice versa_, if below. The
relation of the capacities of the tube and cistern should be
experimentally ascertained, and marked upon the instrument by the maker.
Suppose the capacity to be 1/50, marked thus on the instrument,
"_Capacity 1/50:_" this indicates that for every inch of variation of
the mercury in the tube, that in the cistern will vary contrariwise
1/50th of an inch. When the mercury in the tube is _above_ the neutral
point, the difference between it and the neutral point is to be reduced
in the proportion expressed by the "capacity" (in the case supposed,
divided by 50), and the quotient _added_ to the observed height; if
_below, subtracted_ from it. In barometers furnished with a fiducial
point for adjusting the lower level, this correction is superfluous, and
must not be applied.

The second correction required is for the capillary action of the tube,
the effect of which is always to depress the mercury in the tube by a
certain quantity inversely proportioned to the d