xlviil REPORT — 1853. 



lowest portion of the atmosphere (that which determines the cUmdte of every 

 region) for nearly all accessible points of the earth's surface. An immense 

 number of thermometric observations had been made at fixed stations, or by 

 travellers in almost every part of the globe, but were lying comparatively 

 useless for want of adequate discussion. This task was undertaken some 

 years ago by M. Dove. It was not merely a task of enormous labour, but 

 one requiring great critical acuteness and sound philosophical judgement, and 

 these qualifications M. Dove brought to his work, which has resulted in the 

 excellent maps alluded to, accompanied by a considerable amount of letter- 

 press, full of interesting generalizations, and written in the genuine spirit of 

 inductive philosophy. 



His maps present a great number of isothermal lines, i. e. lines passing 

 through all those places which, at an assigned period of the year, have the 

 same temperature, each line indicating a particular temperature differing by 

 a few degrees from those of the adjoining lines. Besides a large map giving 

 these lines for January and July, the months of extreme winter and summer 

 temperature, there are smaller ones giving similar lines for all the different 

 months. An English edition of these maps has been just published. 



We may easily conceive how a great ocean current of warm water from 

 the tropics may affect the temperature of the atmosphere in the colder re- 

 gions into which it may penetrate, but it is only since the publication of 

 these maps that we have had any adequate idea of the extent of this influ- 

 ence, or been able to appreciate fully the blessings conferred on the shores of 

 North-western Europe, and especially on our own Islands, by the Gulf-stream. 

 This great current, though not always under the same name, appears, as you 

 are probably aware, to traverse the Atlantic in a north-westerly direction 

 till it reaches the West India Islands and the Gulf of Mexico. It is then 

 reflected by the American coast, and takes a north-easterly direction to our 

 own shores, extending beyond Iceland into the North Sea. It is to the 

 enormous mass of heated water thus poured into the colder seas of our own 

 latitudes that we owe the temperate character of our climate ; and not only 

 do the maps of M. Dove enable us to assert distinctly this general fact, but 

 also to make an approximate calculation of the amount to which the tem- 

 perature of these regions is thus affected. If a change were to take place in 

 the configuration of the surface of the globe so as to admit the passage of 

 this current directly into the Pacific across the existing isthmus of Panama, 

 ©r along the base of the Rocky Mountains of North America into the North 

 Sea — a change indefinitely small in comparison with those which have hereto- 

 fore taken place — our mountains, wiiich now present to us the ever-varying 

 beauties of successive seasons, would become the unvarying abodes of the 

 glacier, and regions of the snow storm ; the beautiful cultivation of our soil 

 would be no longer maintained, and civilization itself must retreat before the 

 invasion of such physical barbarism. It is the genial influence of the Gulf- 

 stream which preserves us from these evils. Among its effects on our 

 climate I may mention one which may not be without its local interest along 

 this coast, especially for those who may wish to visit it during the winter for 

 health as well as for pleasure. The temperature of the atmosphere to the 

 north of this island is so ameliorated by the Gulf-stream in the depth of 

 winter, that the isothermal lines for the month of January along the whole 

 eastern coast of Great Britain and the opposite western coast of the continent 

 run north and south instead of following their normal east and west direction, 

 thus showing that Scarborough, or any watering-place on the same coast much 

 further to the north, enjoys as temperate a climate in the depth of winter as 



