254 EF. Loomis—Contributions to Meteorology. 
15 cases (one-seventh of the whole number) in which the pres- 
sure was below the mean. 
The most remarkable case of low pressure occurred Dee. 11, 
1877. On the 9th of December there was an area of low pres- 
sure near Yeniseisk (29°63 inches) accompanied by a tempera- 
ture very much above the mean. On the nextday the barome- 
ter rose slowly and the thermometer sunk rapidly. On the 
1ith the thermometer continued to sink and the barometer also 
descended slightly, but the stations of observation are not suffi- 
ciently numerous to indicate clearly the cause. For six suc- 
cessive days the thermometer remained below —386° C. and the 
barometer rose steadily, standing at 790°4™™ at 9 P. mM. Dec. 
16th. This cold wave came from the northeast and preceded 
the high pressure, and the high pressure of Dec. 16th was ap- 
parently the effect of the long continued and severe cold which 
preceded it. 
The case of Dec. 5 and 6, 1878, was simiiar to the preceding. 
On the 4th of December there was an area of low pressure near 
Yeniseisk (29°69 inches) accompanied by a high temperature. 
On the next day the thermometer fell rapidly, but the barom- 
eter rose slowly. The thermometer continued very low until 
the 13th, and the barometer rose steadily during the same 
period, with the exception of a slight check on the 8th, the 
reason of which does not fully appear. In this case the cold 
wave appeared to come from the northeast, and preceded the 
high pressure which was apparently the effect of the long con- 
tinued and extreme cold. 
The case of Feb. 14, 1876, was similar to the preceding. On 
the 10th of February there was an area of low pressure near 
Yeniseisk (29°06 inches) accompanied by a temperature much 
above the mean. After this, the thermometer sunk steadily 
until the morning of the 14th, and the barometer rose slowly 
until the 13th. 
The case of Dec. 1, 1882, was also similar to the preceding. 
On the 28th of November there was an area of low pressure 
near Yeniseisk (29°68 inches) accompanied by a high tempera- 
ture. After this, the thermometer fell rapidly, but the barom- 
eter rose slowly. 
All of these exceptional cases appear to have been preceded 
by an area of low pressure, after which the barometer rose slowly 
but the thermometer sunk rapidly, and this sudden fall of 
the thermometer appears to have resulted mainly from the 
previous existence of a cold area in the northeast, which cold 
air pressed rapidly into the area of low pressure as soon as the 
barometer began to rise. 
We have thus found that over Huropasia, areas of high prés- 
sure frequently cover a vast extent of territory; the barometer 
ae 
