44G PROFESSOR K. PEARSON AND MISS A. LEE ON THE DISTRIBUTION 
This list would present in general the same features, as we have already noted_ 
of a continuous change, distributed in contour lines running a little north-east to 
south-west of the parallels of latitude—were it not for the anomalous positions 
of Llandudno, Stony hurst, and Margate. These stations appear to us, especially 
the last, to have anomalies in the values of their constants, which can hardly be 
entirely due to local peculiarities in climate. 
It will be observed that the mode is here again more suitable than the mean as a 
method of recording high barometer. It might, if the point were only supei’fieially 
considered, be deemed a climatological advantage to have the frequency of the 
barometer above its mean value as great as possible. But this is not really so, for 
the simple I'eason that climates which have an extreme range of low barometer have 
a low mean, and, other things being equal, places with low mean have most frequency 
above the mean. On the other hand, places with high means, as a rule, give the 
greatest frequency above the mode. Of course, this relationship is not invariable; 
it follows from the mode being more steady than the mean. Thus, there is a greater 
chance of the barometer standing above the mode in St. Leonards than Laudale, but 
a less chance of its standing above the mean. 
The inequality of the frequencies above and below the mode is not the only point 
of interest connected with the skewness of the barometric frequency-curves. We 
have already noticed that the standard deviation about the mean is a good measure 
of the local variability of the barometer, and may well be used to replace the 
maximum to minimum range.''' But a further question arises owing to the skewness, 
namely, what is the variability above, and what is the variability below, the modal 
height ? These two will not be equal, and an appreciation of their value is of 
considerable importance. 
Some idea of the range above the mode may be obtained by considering’ the 
columns marked H^, H, and - M, in Table IV., which give the theoretical 
maximum height, the observed maximum height and the total theoretical range 
above the mode. Hie disadvantage ol using has already been referred to; it 
may make the range above the mode depend on a single observation in the last year 
ot the whole series. is calculated from the whole sweep of observations, and 
hence, although it may never be reached in actuality, it is a flir better measure 
of range. 
The order of the stations is given in the following diao-ram • 
^ O O * 
An arbitrary raultiple of the standard deviation, <t, may be conveniently taken as the range, if 
required. Thus 6a- practically covers the whole range of barometric-frequency at any station. 
