353 ACCOUNT OF THE ARCTIC REGIONS. 



My object in bringing forward tbese facts, is, to 

 sbow what degree of reliance may be placed upon a 

 limited number of observations upon the tempera- 

 ture of the atmosphere of any country ; and the con- 

 sequent degree of approximation to the truth, which 

 may be reasonably inferred. As the mean annual 

 temperature of a country is probably given, by one 

 year's observations only, to within two or three de- 

 grees of the truth, the mean of a period of eight or 

 ten years, will probably come within one degree of 

 the truth. Therefore, whenever we have a series of 

 accurate observations conducted through such a pe- 

 riod, we may, I think, consider the temperature of 

 that place determined to the fraction of a degree. 



Thus, by a series of thermometrical observations, 

 continued through the space of a few years, the 

 mean temperature of different parts of the earth, 

 particularly of most of the capital cities, and other 

 remarkable places in Europe, has been ascertained 

 to the satisfaction of the philosopher. From the 

 comparison of the results of observations made in 

 different countries, with each other, tracing the 

 clianges of temperature which appear, with certain 

 changes of latitude or situation, some ingenious and 

 philosophical men have endeavoured, by principles 

 of analogy and induction, to determine the mean 

 temperature of every parallel of latitude from the 

 Equator to the North Pole. For facilitating this 

 purpose, Professor Mayer contrived a simple for- 



