100 REPORT—1843. 
in the way in which Mr. Whewell has proved the tide-wave to do round cer- 
tain definite points in the Channel. Now it és a fact, which has of late been 
a good deal insisted upon, viz. that in certain stations the winds do revolve in 
one uniform direction. The vane, for example, at Greenwich (as I am in- 
formed by the Astronomer Royal) makes five revolutions per annum in one 
uniform direction. May not this phenomenon, which, I confess, offers 
otherwise some difficulty of conception, be in effect an indication of some 
such atmospheric node, where a line perpendicular to the strata of the atmo- 
sphere may be regarded as describing a conical surface round the true verti- 
eal? If it be true (as the discussion of the term-observations has Jed to sus- 
pect) that Brussels is in effect such a nodal point, the examination in this 
view of its “ Wind-Rose” would be interesting. 
On the subject of “revolving” storms I am not fully prepared to speak ; 
but there is certainly one point of view in which some of the principal of 
their phenomena would seem capable of explanation in this way of conceiving 
winds of oscillation, and in which they would become traced up, not to “ fun- 
nel-shaped revolving depressions” in the nature of waterspouts, but simply to 
the crossing of two large long waves running in different directions thus :— 
where A A! A" represent the progress of one wave, B B! B" that of the 
other, and ¢ ¢’ ¢’ that of the tornado made by their intersection. The way in 
which a rotary movement in an ellipse or circle, or in some other partly oval 
and partly rectilinear figure, may result from the combination of two recti- 
linear movements of advance and recess, will easily be understood by the 
analogy of the circular and elliptic polarization of light, where rectilinear 
movements of the ethereal molecules are conceived to be similarly combined. 
Some features in such storms are strongly in harmony with this view, viz. 
the fact that in them the direction of the wind at a given locality never 
makes more than one rotation, and not always that; and that in the central 
line of the storm’s progress there is a simple and sudden reversal of direction. 
On the other hand, it must not be concealed that some features militate 
against it; for instance, the fact that such gales are stated always to “ re- 
volve” in one direction, whereas on this view of their origin the changes of 
wind ought to be in opposite directions on opposite sides of the medial line. 
But for the present it must suffice to have pointed out a mode of considering 
the subject of at least certain sorts of winds which, being in the nature of a 
vera causa, resulting from dynamical considerations perfectly general and in- 
defeasible, cannot be without some influence, the only question being that 
of amount. 
Fifty-five pounds of the original grant of 1007. have been expended: should 
the Association order the printing of this report, a portion of the remainder 
may be applied to cover the expense of engraving or lithographing the curves 
above noticed and accompanying this report, expressing Mr. Birt’s observed 
waves. ‘The publication of all the projected term-curves would incur a more 
serious additional expense without a corresponding benefit. In furnishing 
the basis of the above discussions they have performed their office, though as 
records they should be carefully preserved. 
(Signed) J. F. W. HERSCHEL. 

ERRATA, 
Page 72, line 44, for Dec. read Sept. 
Page 74, lines 36, 38, 39, for Sept. read Dec. 
Page 75, lines 2, 43, for Sept. read Dec. 
