United States Weather Maps for 1872-1874. 13 
at 27°; at 9.80 Pp. m., 86°; and at 9.385 P.M. at 40°; after 
which there was but little change till near noon of the next 
day. The preceding observations show a rise of the thermom- 
eter amounting to 39 degrees in 35 minutes. 
On the 15th of January, the thermometer had been above 40° 
all the morning, with a fresh southwest wind. About 11.80 
A. M. the thermometer stood at 52°. The wind then suddenly 
backed to northeast, and at 12.30 P.M. the thermometer stood 
at 4°; being a change of 48° in one hour. Another observer, 
who is pronounced perfectly reliable, says that between 11 
A. M. noon a thermometer fell from 58° to 22° (that is, 
thirty-six degrees) in five minutes. The annexed figure on 
Thermometer. 
Jan. 14. Jan. 15. 
noon. 6 midn. 6 noon. 6 Ravenister. 
50°F an. 1 a 
— 6 noon. 6 midn. 6 noon. 6 
40-7-— 
24:8 
30 aa 
24-7 
104+-—+—— LT | 245 N 
0 ago 24°4 
Peas 
the left will perhaps give a better idea of the extent and sud 
denness of these changes of temperature than would be derived 
from a simple description. The entire curve shows the state 
of the thermometer for nearly two days, from 5.43 A. M., Jan. 
14th, to 9 Pp. M., Jan. 15th, according to the observations made at 
the signal service station. The figure on the right shows the 
changes in the pressure of the atmosphere during the same 
Period. On the 14th the barometer fell from 24°88 to 24-40 
inches, and on the 15th it rose again to 24°76 inches. 
hese changes of temperature and pressure which were 
hoticed at Denver, were the effects of a considerable storm 
1p came from the northwest, and whose center passed on 
the east side of Denver, within about 250 miles of that place. 
cH storm was accompanied by high winds and gales in Colo- 
Fe and Kansas. It probably did not differ materially from 
the Winter storms frequently experienced in other portions of 
he United States, except in the extreme suddenness of the 
