171 
The particles composing any fluid mass are subject to 
various changing influences, in particular of pressure, when- 
ever they are moved from one situation to another. In this 
way they experience changes of temperature altogether 
independent of the effects produced by the radiation or con- 
duction of heat. When all the parts of a fluid are freely 
interchanged and not subject to the influence of radiation 
and conduction, the temperature of the fluid is said by the 
Author to be in a state of convective equilibrium. The 
equations of convective equilibrium in the atmosphere investi- 
gated by the Author are as follows, II, T, and W denoting 
the pressure, temperature, and mass per cubic foot of the air 
at the earth’s surface, and p, t, and p the same qualities of 
the air at any height x. 
which is the known relation between temperature and 
pressure. 
the deduced relation between pressure and density ; and 
dp z= — p dx — (3) , 
the hydrostatic equation, the variation of gravity at different 
heights being neglected, and the weight of unit mass (lib) 
being taken as unit of force. Hence by integration, 
t Wx k — 1 „ n 
- = 1 3 Or if, for brevity, we denote — by H, 
ifl k W 
t x k — 1 
~T~ H~T~ 
■(4) 
From (4) and (1) it appears that temperature and density 
would both vanish at the very moderate height 
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