HORARY CORRECTIONS. 257 
For the transition climate from Camp No. 32 forward to near the boundary of New Mexico, a 
modified scale with a larger range was employed. 
Horary corrections applied from Camp No. 32 to Camp No. 50, near the Laguna Colorado. 
6 a. m —.007 2 p. m +.015 
Ta. m 一 .020 3p.m +.030 
8 m 一 .030 4p.m 十 .045 
Ge meus 一 .040 5p.m 十 .050 
10 a. m —.050 6 p.m 十 .030 
lla. m r —.055 7p. m 十 .020 
12- mec —.025 8 p.m 十 .005 
1 p.m —.005 9p.m 十 .000 
For New Mexico, and the arid climates of the remainder of the route, a still larger horary 
variation was found to exist. The quantities were determined from hourly observations, made 
by the survey at Albuquerque, from the 3d to the 10th of October, for sixteen hours of the day, 
and continued for six hours daily to November 8. Observations at Zuñi every fifteen minutes 
on November 22, were also used to establish this curve. 
The curves drawn from these observations will be seen to exhibit similar features in all cases, 
and the corrected curve from which the scale was taken to be so symmetrical as to leave no. 
doubt. of the accuracy of this unusually large measure of variation of MON through the 
successive hours of the day. 
` Scale of horary corrections applicable to the arid climates of New Mexico and California. 
6 a. m —.010 | 2 p. m......... 十 .030 
7 a. m —030 | 3pm 十 .040 
8a. m —045 | 4 Pp. m...... , 十 .050 
9 a. m 一 .050 ۱ 5 0. m +.045 
10 a. m —.057 Ee me +.035 
lla. m 070 T p. m 十 .025 
12 m "۰ت‎ A 十 .010 
1 p. m... +.009 JL | 9 p.m 十 .005 
This important correction for barometric readings used in the determination of heights has 
scarcely been referred to in previous surveys ; and the large values it certainly has along this 
line should be verified more fully than they yet have been. The correction for horary variation 
is probably large and important over all the interior, in which the barometer is the chief reliance 
for determining elevations. 
On the immediate coast of the Pacific, this measure of horary variation returns to quantities 
differing much less from those which belong to the Atlantic States, and it is not clear whether 
the large daily range of pressure in the interior belongs to aridity in connection with altitude, 
or to altitude alone. It is believed, however, that the districts having extreme daily changes of 
temperature, whether caused by altitude or dryness of climate, are affected by similar measures 
of daily variations of pressure, though the hours at which the extremes occur are later as the 
district is more elevated. 
33 m 
