ADIABATIC CHANGES OF MOIST AIR— NEUHOFF 459 



Now for — o° C. we first compute 



45.2 

 log p' - —= 2.5645 



and each corresponding subsequent expression is deduced from the 

 preceding by the addition of 



— m log -^ 

 *■ 2 



There follows then the solution of all the equations 



log P' «- ~, = N 



(the numbers given in column 8) by numerical trials The app oxi- 

 mate values can easily be estimated from the progressively diminish- 

 ing differences of pressure, so that with the first or second trial we 

 shall hit upon the right value and for the computation of the quo- 

 tient a/p' we use Crelle or other practical multiplication table. 

 The values of p' resulting from the solution of the equations N are 

 found in column 9 of table A; adding to each p' the saturation vapor 

 pressure e m as given in table 2 corresponding to the temperature 

 we obtain the values of the total pressure p as given in column 11. 

 The values of the pressure are only given to the nearest whole 

 millimeter, which is quite sufficient for present consideration. 



We will now compare the final result with that given by the rigor- 

 ous adiabat for the initial temperature 20 and pressure 760. 



The principal difference in the computation itself lies in the fact 

 that m remains constant for the rigorous adiabat during the whole 

 course of each stage and that each new condition can be derived 

 directly from the original initial condition itself. 



If we assume as the initial quantity of moisture £ ==. x x = 14 

 grams and consider this as remaining constant, then from table 

 4 we have for the rain stage m = 3.64. For the final temperature 

 + o° C. we obtain 



40.0 



log p' - —7- = 2.5741 



P 



whence follows for the adiabat p' = 458.5™™ for o° C, whereas for 

 the pseudo-adiabat we had p' = 460 in table A, wherefore the dif- 



