Natural History. \95 



found, has been pronounced his most important 

 discovery/ 



Mr. Kir WAN has carried the discoveries and 

 improvements of JMayer considerably further. 

 By means of the equation formed by the philoso- 

 pher of Goettingen, but rendered much plainer 

 and more simple, he has calculated the mean an- 

 7mal temperature of every degree of latitude be- 

 tween the equator and the pole. He has also cal- 

 culated the mean nionthlij temperature of that part 

 of the ocean which lies between the eightieth 

 degree of northern, and the forty-fifth of southern 

 latitude, extending westward as far as the Giilph 

 Stream^ j^nd to within a few leagues of the coast 

 of America; and for all that part of the Pacific 

 Ocean reaching from 45*^. north to 40^. south lati- 

 tude, and from 20^. to 275°. east longitude. This 

 immense tract of ocean he calls the standard. From 

 these calculations he has deduced a number of im- 

 portant principles, of great practical utility, and 

 w^hich place him among the most distinguished 

 meteorologists of the eighteenth century. 



The origin, qualities, and laws of Winds have 

 been diligently studied, during the period under 

 consideration, but not with the same success that 

 has attended inquiries into other branches of me- 

 teorology. No satisfactory theory has yet been 

 formed on this subject, owing to the want of ob- 

 servations sufficiently numerous, of the exact times 

 and places where they begin and cease to blow, 

 but chiefly to our imperfect knowledge of the 

 means by which great regions of air are either 

 suddenly produced or destroyed. The discoveries 

 of modern chemists evince that air is perpetually 

 subject to increase and diminution, from its com- 

 bination with other bodies, or its evolution from 



e See An Estimate of the Temperature of Jifcrent LalituJcs, by RiCHAKD 

 I^IRWAN, £sj. F. R. S. 5cc. 



