Sect. V.] AIe/eoro!ogi/. 049 



imparted to the atmospliere by the earth itself; 

 and thus explained by what means tlie winter's 

 cold is rendered so moderate as to make the colder 

 climates inhabitable. On the ground of this dis- 

 covery be calculated, with great sagacity, the 

 rnaximum and minimum of heat, in every latitude, 

 for the summer and winter solstices 3 and though 

 his calculations are not always found to coincide 

 with facts, yet they have proved highly instructive 

 and useful to subsequent inquirers. De Mairan 

 was followed by Mayer, the celebrated astro- 

 nomer of Goettingen, who, in a few pages, did 

 more to solve the difficulties that occurred on this 

 subject than any of his predecessors. Me first 

 pointed out to meteorologists the necessity of fol- 

 lowing the method long used by astronomers; 

 namely, of first finding the mean of certain large 

 periods, as years and months (gradually correcting 

 the errours that may be discovered), and afterwards 

 finding an equation whereby to' correct aberra- 

 tions arising from height and situation. He even 

 proceeded so far as to give an equation to correct 

 the effects of height, which in many cases approxi- 

 mates very nearly to the truth : but the equation 

 hy wiiich (knowing the mean annual temperature 

 of two latitudes) the mean annual temperature of 

 every other latitude, and even of the pole itself, 

 may be found, has been pronounced his most ini- 

 portant discovery *. 



Mr. Kir\^•an has carried the discoveries and im- 

 provements of Mayer considerably further. By 



* See An Estimate of the Temperature of diferent Latitudes, hr 

 BW.hard Kirwan, esq. F.R.S., ^'c. 



