- 
E. Loomis— Observations of the U. S. Signal Service. 7 
cases occurred during the seven winter months of observations, 
and they occurred most frequently in the month o 
this table is too extensive to be published entire, I selected 
those cases in which the temperature at Pike’s Peak was at least 
45° lower than at Denver. These cases are exhibited in the 
following table, where column first shows the number of refer- 
ence; column second shows the date of the observation. [The 
.80 A, M. observation is denoted by the figure 1 attached to the 
date ; the 4.35 Pp. M. observation by the figure 2, and the 11 P. M. 
observation by the figure 3.] Column third shows the tempera- 
ture on Pike’s Peak; column fourth the relative humidity, and 
column fifth the direction and force of the winds on Pike’s 
Peak ; column sixth shows the temperature at Denver; column 
seventh the difference between the temperature at Denver and 
that at Pike’s Peak; column eighth shows how much the 
pressure at Denver differed from the mean pressure for the 
month; column ninth shows the relative humidity; column 
tenth the direction and force of the winds; and column elev- 
enth shows the direction of the upper clouds at Denver, with 
the amount of cloudiness (estimated in fourths of the visible 
heavens.) 
The average humidity at Pike’s Peak at the time of these 
observations was sixty-two, which was exactly the average 
humidity for the entire year 1878. The winds on Pike’s Peak 
generally blew from a western quarter, and in only nineteen 
cases did they blow from any eastern quarter. The average 
velocity of these easterly winds was twelve miles per hour. 
The fluctuations of the barometer at Denver were generally 
small, being sometimes above and sometimes below the mean; 
but the average pressure was 0°10 inch below the mean. The 
easterly and westerly winds at Denver were almost exactly 
equal in frequency, but the velocity of the west winds was 
more than double that of the east winds. The upper clouds at 
Denver were almost invariably from the southwest or west, an 
were never from any easterly point, and the average cloudiness 
of the sky was more than one-half. The most noticeable cir- 
cumstance exhibited by this table is the dryness of the air at 
Denver, the average relative humidity being only fifteen per- 
cent. There appears to be only one possible explanation of the 
source of this dry air, viz: that it came from the west side of 
the Rocky Mountains. 
The facts thus stated appear to show that at the dates given 
in the preceding table there was seldom any extraordinary dis- 
turbance on Pike’s Peak. In two cases (Nos. 60 and 61) hail 
was reported ; in four cases (Nos. 23, 32, 43 and 59) sleet was 
reported, and in fifteen other cases there was either rain or 
snow. These facts seem to indicate an occasional uprising of 
