Atmosphere, law of repulsion in the particle* of. 



1(5. In general if the particles of a fluid repel each other with forces 



varying- inversely as the *r* power of their distances or as -^ & 



on 



d represent the density of any part, and c the compressive force upon it ; 

 then 



c varies as d -> or varies as 



It appears by experiment, that the compressive force of atmospheric 

 air varies as the density, ,*. ~ = 1 or n . = 1 ; consequently the par- 



ticles of air repel each other with forces which vary inversely as their 

 distances. 



Cor. This fluid will be elastic, if n 4. 2 be positive. 

 Atmosphere, temperature of. 



17. Various formulae for the mean temperature of any place at the level 

 of the sea. 



Playfarr^s formula. 



t = 58 _j_ 970 x cos 2 latitude. Fahrenheit. 

 When 2 latitude is greater than 90o, cos 2 latitude is negative. 



Leslie's formula. 

 t cos 2 lat x 29. Centigrade. 



Daubisson's formula. 

 t 27 X cos* lat. Centigrade. 



Brewster^s formula. 



For the old world, t 81 |o x <*os lat. Fahrenheit. 

 For the new, t = 81 x cos 2 lat. x 1-13. 



Atkinson'* formula. 



Deduced from Humboldt's observations in the new world. f See Mem. 

 Astron. Soc.) 



t = 97, 08 x cos I lat. 100, 53. Fahrenheit. 



