432 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 51 



to the atmospheric processes has hitherto been greatly hindered by 

 the fact that memoirs on this subject are distributed through the 

 greatest variety of periodicals, most of which are very difficult of 

 access. On the other hand, the want of tables and diagrams is 

 felt all the more since even the diagram of Hertz is at the present 

 time no longer easily accessible. In the handbook of Zeuner 11 

 moreover, in which the changes of condition of moist air are fully 

 considered this subject is treated only as a side issue. 



The present publication has for its object to respond to the 

 existing needs in the most perfect manner possible. In this memoir 

 the equations for the determination of changes of condition in 

 moist air are given under rigorous physical assumptions and with 

 an exact mathematical treatment of the problems. 



It has been possible to so arrange the results that the processes 

 during the different periods can be expressed by one single, simple, 

 and general formula, whose application to special cases by means 

 of the accompanying tables demands only the smallest amount of 

 time and trouble. 



Moreover, a new adiabatic diagram for the diminution of tem- 

 perature with altitude has been constructed which makes it possible 

 to accomplish a graphic determination of the adiabatic changes of 

 condition of moist air and that too by use of the above-mentioned 

 extremely convenient net work of squares. In this diagram the 

 pressure is represented by straight lines crossing the page on a slant 

 and is read off by the scales on either side of the diagram. By 

 reason of the diversity in the style of treatment of the systems of 

 lines and by the use of a red tint for the network of squares, the 

 use of the table is made easier and its perspicacity is increased. 



The accompanying tables, i to 6, thus serve as auxiliary for the 

 computation whereas table 7 considered as a table of adiabatics 

 gives in one view for every 2 C. the associated values of the pressure, 

 temperature, altitude and change of temperatuure per 100 meters, 

 of saturated air, ascending adiabatically. 



The utility of the tables, their accuracy, and method of use are 

 illustrated by practical examples. 



At this place I would express my sincere thanks to my highly 

 honored master, von Bezold, for the stimulus that he has given me 

 in the accomplishment of this work as well as for his kind and active 

 interest in it. 



11 Zeuner: Technische Thermodynamik, Bd. II. Leipzig, 1890. 



