E. W. Morley— Oxygen in the Air. 169 
variation with ease. But no such variation has been detected 
even in samples of air collected at the greatest elevations 
attainable. 
mph Bao of O | Per cent of O. Fr ivirye Beta Aad O | Per cent of O. 
0 26°52 ¢ 20°96 % 10 22°41 g 18°31 ¢ 
1 26°08 20°68 20 18°93 15°92 
2 64 20°41 30 16°00 13°79 
3 95°21 20°14 40 13°62 11°91 
4 24°79 19°87 50 11°42 10°25 
5 24°38 19°60 60 9°65 8-80 
6 23°97 19°34 70 8:16 
J 23°57 19°07 80 6°89 6°45 
8 23°18 18°82 90 5°82 5°50 
9 22-19 18°56 100 4°92 4°69 
But although this is the case, it is certain that in the atmo- 
sphere of the same place at different times the oxygen varies 
by more than one-fortieth of its average amount. Variations 
so large as this are rare, but variations of the one-hundredth or 
two-hundredth part are common, It therefore seemed to the 
writer proper to examine whether facts bear out the conjecture 
that certain great and sudden local depressions of temperature 
are caused by the descent of cold air from the upper part of 
the atmosphere, and that such air may by its poverty in oxygen 
throw some light on a question in meteorology and a question 
concerning the physics of a mixture of different gases. 
the number of Wiedemann’s Annalen for April of the 
current year, Jolly has published the results of numerous and 
Very accurate analyses of atmospheric air. He asserts a con- 
On the writer's theory, a sample of air collected at the center 
an area covered by a descending current of cold air woul 
