(289) 
A POSSIBLE LUNAR INFLUENCE UPON THE VELOCITY 
OF THE WIND AT KIMBERLEY. 
(Fourth Paper.) 
By J. R. Sutton. 
(With one Text-figure.) 
The aro'uinent upon which the previous papers have been based is the 
almost axiomatic one that since the moon can raise an appreciable tide in 
the atmosphere it must also l)e able to create an appreciable wind. For 
there cannot be an air tide without an air movement. The wonder is that 
the Cjuestion lias not been tested before for various places lying between the 
temperate zones. But the expectation with which the inquiry was started, 
nameh% that the air movement would be a direct function of tlie air tide, 
and hence show a simple small semi-diurnal oscillation of speed, has not 
been exactly verified. A variation of velocity depending- on the hours of the 
lunar day has been found, but surprisingly large and of a special type, which 
would appear to be little more directly related to the air tide than the 
normal diurnal winds are to the normal diurnal pressures. The object of 
that portion of the inquiry with which this paper deals is to determine 
whether there are any points of agreement between the air tides and the 
lunar wind period sufficiently definite to form the nucleus of a theory wdiich 
could be used to explain the comparatively great air speeds attributable to 
the moon's influence. 
For this purpose the air-tidal variation at perigee and at apogee has been 
determined for ten years of observation, 1897 to 1906, as shoAvn in Table I, 
using the hourly pressure deviations from the monthly means for the day 
of perigee and of apogee, together with those for the day before and the day 
after. The period is slioiter than that used for the wdnd, but since the air 
tides are fairly regular it is probably sufficiently long for the immediate 
purpose ; and in any case the arithmetic involved is as much as my wife and 
I can undertake for the present. In order to avoid the use of minus signs 
the tabular quantities have all been augmented by one inch : thus, e. g. 
1-0023 means -f -0023, and '9950 means - '0050. 
* By Sabine's method, Phil. Trans., 1847. 
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