224 



November 1878 and terminating the end of August, 1879, or only 

 extending in part into September; the depression of the maximum 

 temperature beyond that of the minimum, while it lasted, being 

 due no doubt to the excess of rain and cloud,* which would serve 

 equally to lower the day temperatures and to raise the night tem- 

 peratures, shutting Qut the sun's raj^s in the former case, and 

 checking terrestrial radiation, which is the great promoter of night 

 cold, in the latter. 



There has been, of course, speculation as to the cause of such 

 abnormal weather, continued, too, over so many months. No 

 satisfactory explanation of it, however, has yet been given, and 

 the science of meteorology is hardly in a sufficiently advanced 

 state to give one. Persistent wet, whether in the form of snow or 

 rain, would naturally be attended by a low temperature, and there 

 might be frequent interaction between these two conditions of 

 weather ; a low temperature causing an increased condensation of 

 atmospheric vapoui-, the evaporation, on the other hand, that 

 takes place after much rain, having a tendency to depress or keep 

 down the temperature. Of these two, if we suppose cold to have 

 been the first agency at work, wc naturally ask what has occasioned 

 the cold 1 But before saying anything on this head, it may be 

 remarked that lengthened periods of cold and wet, similar to Avhat 

 Ave have experienced in 1879, are not so entirely without precedent 

 as some might be inclined to think. A writer in one of our 

 periodicals,+ sometime back, made mention of several instances 

 during the last hundred years or more, obtained from an old 

 register, in which there had been like periods of cold, of longer or 



• Sunshine at Greenwich.—" In the first half of the year 1S79— the 26 weeks 

 ending with Saturday, the 28th of June— there were only 471 hours of sunshine 

 registered there. In the corresponding period in last year there were 643 

 ho.'.rs of snnshine. The deficiency in 1879 occurred in the second quarter of 

 the year." {Times ; July, 1870.) 



+ Or in a Newspaper, I cannot say which, for I have unfortunately lost the 

 reference, and can only speak of the matter in a general way. 



