74 TWENTIETH ANNUAL KEPORT ON THE STATE CABINET. 



rent is retained to raise the temperature of all the places that are 

 thus sheltered from the polar current. 



On our own continent we have, in like manner, the Eocky 

 mountains stretching across the continent from southeast to north- 

 west. If now we select for comparison some places in the same 

 latitude, one on the Pacific coast, another on the plain east of the 

 mountains, and another still farther east and east of the Missis- 

 sippi, we shall see the efiects of this mountain range. Thus : 



Summer. Winter. Year. 



f Fort Humboldt, Cal 57.4 45.2 52.1 



Lat. 40 { Fort Kearney, Neb 71.5 23. 47.7 



|^Milton,Ind _ 78.4 29.7 52.2 



.J. - .„ ( Fort Steilacoom, W. T 62.9 39.5 50.8 



•^^^•^' I Sandy Lake, Min. ._ 64.8 14. 39.9 



Farther south, the difference is of course much less. But in 

 latitude 40, with the summer 14.1 deg. warmer than on the Pacific 

 coast, the winters are 22.2 deg. colder, and the average for the 

 year is in consequence 4.4 deg. colder on the western side of the 

 Rocky mountains ; while in Indiana, beyond the more immediate 

 effects of this obstruction to the polar and return current, the sum- 

 mers are 6.9 deg. and the winters 6.7 deg. warmer, with a differ 

 ence in the general average 4.5 for the year. Farther north, at 

 latitude 47, the contrast becomes still more remarkable ; with 

 summers 2.1 deg. warmer than on the Pacific coast, the winters 

 25.5 colder, and a difference in the general average for the year 

 of 10.9 



Or, to compare the effects in another way : The isothermal for 

 winter that passes through the places of western New- York that 

 lie along the borders of Lake Ontario, and from ten to twenty 

 miles south, starts on the Pacific coast far north of Sitka, 57 deg. 

 north latitude, and reaches in New Mexico, just east of the moun- 

 tains, the low latitude of 36 deg., and then reaches ours, about 43, 

 in Michigan ; while the isothermal for our summer, 67, starts 

 from latitude 30 on the Pacific coast, and passes the plains just 

 east of the Rocky mountains in latitude 35. Thus the cool winds 

 from the pole which pass along down by the side of the moun- 

 tains, make even the summers as cold at thirty-five degrees of 

 latitude as ours are at forty -two or three ; or, in other words, 

 these winds make a difference in temperature equal to eight de- 

 grees of latitude. 



V. The last cause to be named is, proximity to internal lakes 

 and streams of neater. 



