6 FE. Loomis— Results from an examination of the 
greatest depression was less than at western stations in the same 
latitude. 
portions of the United States. 
It will be noticed that from Dec. 23d to Dec. 27th, the de- 
pression of temperature on the summit of Mt. Washington (ele- 
vation 6,285 feet) was generally less than at other stations in its 
vicinity. On the 24th, the depression on the summit was about 
e same as near its base; but on the 26th the depression was 
twenty degrees less than near the base, indicating that at this 
time the vertical thickness of the cold stratum of air did not 
much exceed 9,000 feet. 
The fluctuations of temperature observed from Dec. 16 to 
Dec. 27, 1872, were similar in their general features to those 
occurring every winter, but they were remarkable for the long 
continuance of an unusually low temperature. What was the 
cause of this protracted period of severe cold? It can 
scarcely be doubted that this low temperature was, at least, 
in part, due to causes in operation beyond the limits of the 
United States. It is noticeable that during this period the 
barometer was unusually high, and there was a general corre- 
spondence between the curves of high pressure and of low 
temperature. If then we can discover the’ cause of the bigh 
rometer, we shall probably find the explanation of the low 
temperature. 
In my third paper (vol. x, p. 8) I gave a table showing the 
number of cases in which an area of high pressure was found 
on different sides of an area of low pressure during a period of 
three years. These numbers are as follows: 
