ANNOTATIONS AND ADDITIONS. 117 



of the country to possess a proper continental character, i. e. hotter 

 summers and colder winters. " It is proved/' says Ferry, " by our 

 thermometrical data, that the climate west .of the Alleghany Chain 

 is more excessive than that of the Atlantic side/' At Fort Gibson, 

 on the Arkansas River, which falls into the Mississippi in lat. 35 

 47', with a mean annual temperature hardly equal to that of Gib- 

 raltar, the thermometer in the shade, and without any reflected heat 

 from the ground, has been seen, in August 1834, to rise to 3 7. 7 

 Reaumur, or 117 Fahrenheit. 



The statement so often repeated, although unsupported by any 

 thermometric measurements, that, since the first European settle- 

 ments in New England, Pennsylvania and Virginia, the eradication 

 of many forests on both sides of the Alleghanies had rendered the 

 climate more equable (i. e. milder in winter and cooler in summer), 

 is now generally doubted or disbelieved. Series of trustworthy ther- 

 mometric observations in the United States hardly extend so far 

 back as seventy-eight years. We see in the Philadelphia observa- 

 tions, that, from 1771 to 1824, the mean annual temperature has 

 hardly increased 1.2 Reaumur (or 2. 8 Fahrenheit) a difference 

 which is attributed to the increased size of the town, to its greater 

 population, and to the numerous steam-engines. The difference may 

 possibly be merely accidental, for I find in the same period an in- 

 crease of mean winter cold, amounting to 0.9 Reaumur, or 2 Fahr- 

 enheit; the three other seasons had become somewhat warmer. 

 Three-and-thirty years' observations at Salem, in Massachusetts, 

 show no alteration at all : the annual means oscillate, within a de- 

 gree of Fahrenheit, about the mean of the whole number of years ; 

 and the winters of Salem, instead of having become milder, as sup- 

 posed from the destruction of the forests in the course of the thirty- 

 three years, have become colder by 1.8 Reaumur, or 4 Fahrenheit. 

 (Forry, pp. 97, 1Q1, and 107.) 



As the east coast of the United States is comparable in respect to 

 mean annual temperature, in equal latitudes, to the Siberian and 

 Chinese coasts of the Old Continent, so also the west coasts of Europe 

 and America have been very properly compared together. I will 

 only take a few examples from the western region on the shores of 

 the Pacific, for two of which (Sitka in Russian America, and Fort 



