Observed in the amount of Oxygen in the Air. 427 
The deficiency of oxygen noticed on the 28th was well ex- 
plained by the occurrence of an area of high pressure over 
Missouri, with winds radiating around it. On the 29th, this area 
was central over eastern Tennessee, the winds well exhibited — 
the spreading out in all directions which suggests the descent 
of upper currents. The oxygen found on these days was 
020957, a fall of 0:°00011 as compared with the 26th. 
The morning of February 9th affords a reasonably clear proof 
that the surface winds implied the descent of upper currents. 
There was an area of low pressure over the mouth of the Mis- 
sissippi, and one of high pressure on the northern half of the 
Atlantic seaboard. Hast of the Appalachians, no winds were 
directed across the mountains, while on the western side of the 
mountains, from Louisville to Montreal, the winds were all ra- 
diating from a center in Pennsylvania, with a mean velocity of 
eight miles an hour. On the next day the stations near Louis- 
ville were involved in currents coming from the gulf, and gen- 
tle winds were blowing from the seaboard toward the Appala- 
chians. There was an area of low pressure in Michigan. The 
obvious acceleration of the winds in the lower lake region sug- 
gests a continuance of the descent of upper currents which 
to 020948. 
There was a deficiency of oxygen on the 13th. There was 
a general brisk motion of winds voward a center of low press- 
ure in Maine, with nothing explaining the observed deficiency. 
On the 15th, there was an area of high pressure with its 
center over New Jersey. Winds blew away from this center in 
every direction. No deficiency of oxygen was observed, how- 
ever, on the morning of this day, but on the next day the 
oxygen found was 0:20951, a fall of 0°00009. Nothing on the 
- maps of this morning explains this deficiency. 
On February 21st, there was an area of high barometer over 
the lower Mississippi valley. inds were blowing outward 
in all directions. e inference that there was a descent of up- 
per currents is perhaps a fairly probable one. The oxygen was 
not affected at this place, being found to be 020964. On the 
22d there was an areaof low pressure over Lake Superior, tow- 
ard which winds were drawn with increasing velocity from the 
northwest slope of the Appalachians, while on the other side 
of the mountains the winds show no connection with the sys- 
tem prevailing on the northwest side. Over the region from 
Louisville to Kingston the mean velocity of the winds was 
