ON “QUIET” DAYS DURING THE ELEVEN YEARS 1890 TO 1900, ETC. 
359 
however, the maximnm and minimum in any single day seldom come at exact hours, 
so that if we confine ourselves to hourly values we do not as a rule hit on either the 
absolute maximum or absolute minimum, and the difference between the Greatest and 
least of our hourly values as a rule is less than the amplitude proper of the diurnal 
movement. Again, the times of occurrence of the maximum and minimum reallv 
vary from day to day, so that the range we obtain by considering mean hourly values 
from a series of days tends to be less than the arithmetic mean of the ranges deduced 
from the individual days results. This last consideration doubly requires to be taken 
into account in connection with inequalities for the year or for a season. 
