12 
The Colorado Experiment Station 
record of the lowest and highest temperature for each day of 
the year is kept at each station. The ditference between the 
maximnm and miniminn temperatures of the day constitutes 
the daily range of temperature. The average of the two gives 
the mean temperature. The dilference between the highest and 
lowest temperature during the month gives the monthly range. 
At the end of the year we obtain the annual mean temperature, 
the monthly and daily means of temperature, the daily, 
monthly and yearly range of temperature. 
The rain gage which is used to measure the precipitation 
has an inner receptacle that magnifies the amount ten to one, 
making it possible to read to one hundredth of an inch with 
accuracy, and though the different elements vary considerably 
from month to month and year to year, the averages of all the 
years and of all the separate months alford a fairly accurate 
estimate of what we may expect each year and each month. It 
is only from the average of a long series of observations that 
an accurate opinion may be formed of the temperature and pre¬ 
cipitation of a locality, and also, what is of equal importance, 
the extremes that are liable to come. The records in this bul¬ 
letin are brought up to the end of 1917 and extend far enough 
back to give the average results and a fairly good knowledge 
of the climate of those portions of the State reported upon. 
That it is possible to place before the public the data from 
these stations depends upon a great deal of patience, care and 
accuracy on the part of the observers, and much credit is due 
those observers whose only recompense has been in giving to 
the public a portion of their time and labor, in some cases 
twenty to thirty years, in order that we may have knowledge 
of the climatology of the State in which we live. 
Throughout all tables, unless otherwise stated, Fahrenheit 
degrees have been used. 
THE ARKx4NSAS V ALLEY SUBSTATION 
This station is located near Rocky Ford, Colorado, and 
was established by the Colorado Experiment Station in 1888, 
and records have been taken since that time. The elevation of 
the station is 4,180 feet. Mr. Frank L. Watrous was the ob¬ 
server at this station for a number of vears and was succeeded 
u 
by Mr. W. F. Crowley. Mr. H. II. Griffin was observer at that 
station from February, 1898, to February, 1903, and was suc¬ 
ceeded by Atr. Philo K. Blinn, wlio is still in charge. 
The season is some longer than in the northern part of 
the State, and the mean temperature a little higher, especially 
