HYPOTHESES BEARING ON CLIMATIC CHANGES 683 
The rhythmic curve which represents these oscillations 
should have an increasing or declining amplitude, according to 
the advance or decline of the topographic conditions which con- 
trol the depletion of the atmosphere. This brief sketch needs 
much elaboration and qualification, but as the studies are still in 
progress, and the paper has already transgressed the limits due 
the occasion, it must be deferred. 
T. C. CHAMBERLIN. 
