7 ee ee . i LEE ; 
Axial Oscillation, 181 
- Oscrtiations or THE Axis or Roratron.—We may infer that 
‘the centrifugal force, within the body of the revolving storm, will 
seldom be equally balanced on all sides, by the exterior pressure 
which is indicated by the barometer, and that the impulsion 
which results from the temporary predominance of pressure on 
any side, will be propagated around the axis, causing the latter 
to move in a series of spiral revolutions, or curvilinear deviations, 
during its progression. This revolving oscillation may often be 
observed, even where there is no progression of the whirling 
body; as in the case of a vortex in water discharging into an 
orifice or through a funnel. This oscillation of local pressure 
and the eccentrical revolution of the axis, may go far, among 
other causes, in explaining the flaws, puffs, gusts, and squalls, as 
they are loosely and sometimes interchangeably called, which are 
sO very common in violent storms ; and, in the larger movements, 
may account for some of the irregular changes previously noticed. 
Puenomena or AxtaL Oscrttation.—The specific course of 
the actual center of gyration, under the oscillations referred to, 
must differ greatly in storms which have different rates of pro- 
gression. It has been shown by Mr. Propineron and Mr. THom 
that the progression of some storms of the Asiatic seas and Indian 
ocean, during some portions of their advance, has been as slow 
‘as three miles and even two and a half miles per hour. 'Vhis re- 
markably slow progress, in connexion with the axial oscillation, 
must produce unusual conditions in places near the center of the 
storm, and may serve to account, in part at least, for the most 
extradelinary series of opposite es successive abiifits veerings, 
and calms, recorded by Mr. Luoyp as having occurred at 
Louis, Mauritius, in March, 1836, in a slow moving hurricane 
which lasted three days.* In this storm, the line pursued by the 
' axis of gyration might have been somewhat like that seen in 
the following figure. : Fig. 1. 
_ In this case, if we suppose 
the circuit of the axial oscil- 
lation to have been equal to 
the diameter of the lull, inclusive of the interior edge of the gale, 
this course of its axial point would produce, on or near its center 
path, a series of oscillating changes not unlike those observed by 
* London Nautical eg June, 1837. 
Sxconp Sentzs, Vol. II, No. 5.—Sept., 184 24 
