Observed in the amount of Oxygen in the Air. 425 
a chances that there was really a fall are here about 8000 
ens 27.—There was an area of high barometer with its 
center well to the north near Lake Superior, Over the ob- 
served half circumference of a circle, the winds were distinctly 
spreading in all directions. The inference that there were 
ownward currents of air is also supported by the fact of an ap- 
parent excess of velocity in the winds passing south over the 
lakes over the velocity of winds approaching them from the 
north. Under the influence of this or some other cause, the 
oxygen found here was 0°20869. 
I cannot explain the deficiency of oxygen on October 30th. 
On November 2d there was an area of high pressure with its 
center over Tennessee and North Carolina. In a general way, 
winds diverged from Kentucky and West Virginia. But there 
were counter currents, so that with the materials at hand we 
are not authorized to say that a descent of upper currents is 
indicated with any such probability as to explain the deficiency 
of oxygen found. The amount was 0:20950 
November 7th.—There was an area of high pressure with its 
center over Mississippi. From this winds diverged all around 
the northern half of a circle. There were some local winds in 
Upper Lake Region which did not conform to this system; but 
the shape of the isobars makes it fairly probable that in the 
region of the lower lakes there were descending currents of air 
from the upper part of the atmosphere. The ee found 
was 020951, a fall of 000020 since the day befor 
November 18th.—There was an area of high feeniing over 
the Indian Territory. From this area winds were aypeme 3 
outward over the observed half circle of stations. An accel 
eration of the winds in the Lower Lake Regions Hip a 
supply of air from above to feed these winds. On the 19th 
this area of high pressure had its center in Southern Ohio. 
The inference of a descent of upper currents . " clear as it can 
be from maps with no more reporting points than those now 
established. The oxygen found was 0 0958, a ‘all of 000010 
since the 17th. On the 18th it had been : 20954. 
n November 23d there was an area of high pressure with 
its center over Southern Ohio, and the inference that upper 
currents reinforced the winds which spread out all around this 
area isa probable one. The oxygen found was 0°20951, a fall 
of 000012 from the preceding day. 
December 3.—At this time there was an area of high press- 
ure with its center over Southern Ohio. It had moved with 
great velocity from over the Upper Missouri city hy winds 
were diverging from a center over Southwestern Ohio. The 
