OF FREQUEiSrCT OF THE BAROMETRIC HEIGHT AT DIVERS STATIONS. 451 
These values are not widely divergent from the previous interpolated values, and 
would for many climatological purposes suffice to describe the barometric frequency; 
indeed, graphically it is hardly possible to show the difference between the 
frequencies curves corresponding to these two sets of constants on the scale of our 
diagrams. The cliief difference is in the skewness of the London distribution, but as 
we have seen in the case of Llandudno, Stonyhurst and Margate, it is the skewness 
which is most influenced by local conditions. The constants and the observed and 
theoretical frequencies for the three telegraph stations London, Cambridge and 
Dover-Dungeness, are given in the form of supplements to our tables. They are of 
very considerable interest, but they have not been Included in the general returns 
based on the selected distribution of twenty stations of the second order, as they 
would weight too much the eastern side of the British Isles unless an additional 
series of western stations had also been included.* 
11.—On the Correlation of the Heights of the Barometer at 
Different Stations. 
10. So far as we are aware, no tabulations have hitherto been made of the 
barometric heights at pairs of stations, and yet the degree of correlation between 
stations in different situations is one of extreme interest and importance. We have 
shown that the constants of barometric frequency vary continuously and gradually 
from one end to another of the British Isles. We should accordingly expect a close 
degree of correlation between the heights at different stations. This degree will 
probably be found to vary with the distance at a different rate along and 
perpendicular to the generalised isobars. It may also be greater when a certain 
interval is allowed between the observations at the two stations.! Our present 
object, however, being only to illustrate the general treatment of barometric 
correlation, we have dealt only with three pairs of stations and with contemporaneous 
observations. 
The stations are the following :— 
(1.) Babbacombe and Churchstoke for the eight years 1878 to 1885. 
(2.) Southampton and Laudale for the eight years 1880 to 1887. 
(3.) Hillington and Churchstoke for the eight years 1878 to 1885. 
The I’esults are exhibited in the following three tables .•— 
* We have to cordially thank Mr. R. H. Scott for allowing us to copy the manuscript records of 
the Meteorological Office for these three telegraph stations. We believe that the discussion of the 
frequency of twenty contemporaneous years of the whole system of telegraph, stations would give most 
interesting I'esults, but the labour of copying and reducing only thirteen years for but three stations has 
convinced us that it could hardly be undertaken by private individuals largely occupied with other work. 
t A most interesting in7estigation would be the degree of coiTelation between suitable North- 
American and British stations, when the interval between the observations was varied from one up to 
sis or seven days. Similar investigations for British and Continental stations might easily give 
important results bearing directly on the prediction of barometric changes. 
3 M 2 
