858 
Journal of Agricultural Research 
Vol. XXVIII, No. 9 
Precipitation on the Wasatch Plateau is notably less than at similar elevations 
in the Wasatch Mountains. The mean annual precipitation, based on averages 
of from five and one-half years in the oak-brush type to twenty-eight years 1 
record at Manti in the desert valley about 6 miles from the mouth of Ephraim 
Canyon, is summarized by types in figure 5, together with the mean annual 
maximum and minimum temperatures, average number of hours above and 
below 40° F., and the average number of hours of freezing temperature per year. 
—.... Average osmotic pressure of sap in atmospheres of all species tested in each type. 
-. Osmotic pressure in atmospheres of sagebrush sap in different types. 
———— Mean maximum temperatures in degrees F., June-September. 
-Mean minimum temperatures in degrees F., June-September. 
-o—□_ Average number of hours of freezing temperature per year in hundreds of hours. 
—x—x— Average number of hours above 40° F. per year in hundreds of hours. 
-o—o~ Average number of hours below 40° F. per year in hundreds of hours. 
■*■<■■■■■• Mean daily evaporation from Livingston atmometers in cc., July-September, 1916. 
Mean annual precipitation in inches (averageof 5 to 28years record). 
Fig. 5—Summation of sap densities and principal climatic factors by types 
Associated with an increase in altitude is a characteristic decrease in the mean 
maximum and mean minimum air temperatures, and in the average number of 
hours above 40° F. On the other hand, there is the usual increase with elevation 
both in the average number of hours below 40° F. and in the average number 
of hours of freezing temperature. The mean daily evaporation from July to Sep¬ 
tember, inclusive (fig. 5), shows a decided decrease in the aspen-fir type as com¬ 
pared with that in the oak-brush type. In the spruce-fir type the evaporation 
is almost as great as in the oak-brush type, largely because of the fact that the 
climatological station in this type is situated on an open southern aspect which 
