220 PHYSIOGRAPHY 



of supply and loss vary. When loss exceeds supply, the mass 

 of the atmosphere must decrease; when supply exceeds loss, the 

 mass must increase. It is probable that the variations in com- 

 position have been more important than those of mass and volume, 

 at least in the later part of the earth's history. 



REFERENCES 



The following references apply to all of Part III: 



1. DAVIS, Elementary Meteorology: Ginn & Co. 



2. WALDO, Elementary Meteorology: Am. Bk. Co. 



3. WARD, Practical Exercises in Meteorology: Ginn & Co. Also Bull. Am. 

 Geog. Soc., Vol. XXXVII, 1905, p. 385, and Vol. XXXVIII, 1906, p. 401. 



4. HANN, Handbook of Climatology: The Macmillan Co. 



5. BARTHOLOMEW, Physical Atlas: Meteorology: Constable, London. 



6. MOORE, Storms and Weather Forecasts: Nat. Geog. Mag., Vol. VIII, 

 pp. 65-82, and Vol. XVI, pp. 255-305. 



7. MOORE, Descriptive Meteorology: D. Appleton & Co. 



