162 FLORA OP THE ISLE OP MAN. [June, 



The climate is humid, as might be expected in so elevated an 

 island, but temperate and equable withal. The mean annual 

 rainfall is something over 25 inches ; the mean temperature 49° 

 Fahr., — the mean for the three summer months being 56°, while 

 for the winter quarter it is as high as 42°. The following re- 

 marks on this subject, by the Rev. J. G. Gumming, formerly 

 of King William's College in this island, are of sufficient interest 

 to need no apology for their introduction here, especially as the 

 facts therein recorded will doubtless prove a somewhat startling 

 discovery to most of the readers of the ' Phy tologist ^ : — 



" Professor W. H. Dove, of Berlin, has compiled and published 

 a series of tables of temperature for each month, season, and year, 

 at a very large number of places on the surface of the globe, and 

 he has also projected upon maps the remarkable curves of the lines 

 of equal temperature called isothermal, isotheral, and isochimenal 

 lines. The study of these lines lets us into some interesting facts 

 in the science of Climatology. St. John's, in Newfoundland, is 

 7° further south than the Isle of Man; and yet while the mean 

 winter temperature here is almost 42° Fahr., that of St. John's 

 is only 23:j°, i. e. nearly 9° below the freezing-point. Even in 

 their summer they are 4° colder than we are ; and their mean 

 annual temperature is only 6^° above the freezing-point, whereas 

 ours is 18° above it. . . . The Isle of Man is situated upon a cul- 

 minating point of one of these curved lines, the isothermal of 

 50°, or rather 49*84°, as it is given in Professor Dove's tables. 

 The fact of its forming the culminating point shows that there 

 is no other place in the same parallel of latitude which has so 

 high a mean annual temperature. There are places on the 

 same parallel whose summer is hotter, but their winters are 

 also so much colder, that on striking a balance the mean is 

 in favour of the Isle of Man. Still more worthy of observation 

 is the remarkable evenness of our temperature : there is hardly 

 another spot in Europe, as shown by Professor Dove's tables, 

 which presents so slight a difference between the mean summer 

 and the meau Avinter temperature. It is somewhat singular that 

 the places which present a similarly equable temperature are the 

 extremes of Great Britain, viz. the Orkneys and the neighbour- 

 hood of the Land's End. We may remark, however, that the 

 mean summer temperature of Truro, in Cornwall, is half a degree 

 lower than ours, though it is situated 4° to the south of us : 



