122 The Climate of Great Britain. 



cheerfully accept them as more than a counterpoise for hypo- 

 thetical injurious effects on " the outflow of our moral senti- 

 ments/' whatever that may be. 



I proceed to consider the actual variations presented in the 

 course of a year in England. As some selection must be made, 

 I shall select the series of observations which have been made 

 at Greenwich during the present century. It will be gathered 

 from the preceding pages that the range of temperature at 

 Greenwich is at least not less than the average range of the 

 British Isles. Greenwich, also, from its neighbourhood to 

 London, and from the number and accuracy of the observa- 

 tions made there, is obviously the best selection that could be 

 made. It must not be forgotten, however, that the climate of 

 Greenwich is not the climate of the British Isles, and that 

 careful observations made in other places have sufficiently 

 indicated the existence of local peculiarities, which, therefore,, 

 it may fairly be assumed, characterize also the Greenwich 

 indications. 



In Fig. 8 the annual variations of mean diurnal tempera- 

 ture are represented graphically. The figure was formed in 

 the following manner : — A rectangle having been drawn, each 

 of the longer sides was divided into 365 parts, and a series of 

 parallel lines joining every tenth of these divisions was 

 pencilled in. The spaces separating these lines represented 

 successive intervals of ten days throughout the year. The 

 shorter sides were divided into thirty-three parts and parallel 

 lines drawn, joining the points of division. Of these longer 

 parallels the lowest was taken to represent a temperature of 

 32° Fahrenheit (i.e., the freezing point) and the others in order, 

 successive degrees of heat up to 65°. Then, from the Green- 

 wich tables, which have been formed from the observations of 

 forty-three years, the temperature of each day was marked in, 

 at its proper level and at its proper distance from either end 

 of the rectangle. Thus 365 points were marked in, and these 

 being joined by a connected line, presented the curve exhibited 

 in Fig. 3. The lines bounding the months, and the lines 

 indicating 35°, 40°, etc., Fahrenheit, were then inked in and 

 the figure completed. 



The resulting curve is remarkable in many respects. In 

 the first place, it was to have been expected that a curve 

 representing the average of so many years of observation would 

 be uniform; that is, would only exhibit variations in its rate of 

 rise and fall, not such a multiplicity of alternations as are 

 observed in Fig. 3. And this irregularity will appear the 

 more remarkable when it is remembered that the temperatures 

 used as the Greenwich means are not the true average tempera- 

 tures. They were obtained by constructing a curve from the 



