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A POSSIBLE LUNAR INFLUENCE UPON THE VELOCITY 
OF THE WIND AT KIMBERLEY. 
(Second Paper.) 
By J. R. Sutton. 
(With one Text-figure.) 
In a previous paper under the same title reasons were given for 
presuming that the moon must exert a certain amount of influence upon the 
movements of the lower air. Tables were also given showing the variation 
in the velocity of the wind during the course of the lunar day in general, 
and also for the moon south and moon north of the equator. From the 
results of the investigation a mean diurnal range of velocity, attributable to 
the moon, of 0*2 mile an hour was deduced, but much greater ranges when 
the observations were separated into sets for moon south and moon north. 
My opinion at the time was that these ranges were greater than should have 
been expected d priori. In the present discussion, however, the problem has 
been carried a step further, and even greater ranges are deduced. 
We have to do now with the variations in the velocity of the wind when 
the moon is near perigee. The period covered is nearly twenty-two years, 
comprising 288 perigees, from April, 1897, to January, 1919 — that is to say, 
it covers some eight years more of time than the first paper did. Perigee 
was selected partly because some rigid standard of reference was desirable, 
partly because a somewhat greater effect might be anticipated from the 
moon's contiguity, and chiefly for reasons to be developed as we proceed. 
The tabular numbers in the table have been computed as follows : 
Let Vn be the velocity of the wind at any civil hour n ; 
Vn the mean velocity for the same hour of the same month. 
Then Vn —Vn + 10 is a quantity to be transferred to its proper hour of 
the lunar day, the numeral 10 being added in every case in order to 
obviate the necessity for the use of plus and minus signs. A further 
convenience is that in the process of taking means of the quantities V — v 
-f 10, anything greater than 10 is positive, anything less is negative. The 
meaning, therefore, of the numbers in the table is that the normal hourly 
means are supposed to lie upon the straight line z = 10, and that the 
tabular numbers are as deviations from that line. This plan eliminates the 
possibility of any intrusion of solar or other periodicities — which are 
especially liable to intrude where such things as perigee are concerned, 
seeing that at perigee the moon culminates most often in the hours about 
