12 E. Loomis— Results from an eramination of the 
The number of stations at which a difference of 40° between 
the maximum and minimum of the same day was observed in 
1874, is 38, which is 35 per cent of the whole number of 
stations; and among the stations at which so great a differ- 
ence did wot oceur, are Kingston, Toronto and Montreal, in 
Canada, and Pike’s Peak, at an elevation of 14,092 feet above 
e sea 
From the preceding tables it appears that throughout the 
greater part of the United States there is occasionally observed 
a difference of 40° between the maximum and minimum tem- 
perature of the same day, and there are a few places where 
such changes are remarkably frequent. This phenomenon 
occurs most frequently at stations situated between the Missis- 
sippi River and the Rocky Mountains, and at the head of the 
list stand Colorado Springs and Denver. Colorado Springs is 
situated on the eastern side of Pike’s Peak, at an elevation of 
5,935 feet above the sea, and Denver is distant from it about 
60 miles on the eastern slope of the Rocky Mountains, at an 
~ 
elevation of 5,135 feet. 
descent of air from a great height. Colorado Springs an 
Denver are situated where the upward and downward motion 
of atmospheric currents must be uncommonly frequent, and 
they surpass all the other stations of the signal service in the 
magnitude and suddenness of the changes of temperature. An 
instance of this kind has recently been reported which is the 
most remarkable I have ever known. I have received a state- 
ment of the facts from three different sources, all of which 
agree in the main, but they show differences of several degrees 
of temperature, which may be ascribed to a difference in the 
exposure of the instruments. The most moderate statement is 
that furnished by the observer at the U.S. signal service sta- 
tion, and I will therefore adopt his numbers in preference to 
either of the others. 
Storm of Jan, 15, 1875, at Denver, Colorado. 
On the 14th of January, 1875, the thermometer at Denver 
had been below zero all day, with a variable northeast wind. 
At 9 p.m. of that day the thermometer was one degree above 
zero. The wind then veered suddenly to southwest ; and at 
9.15 Pp. M. the thermometer stood at 20°; at 9.20 p. M. it s 
