84 EF. Loomis—Reduction of Barometric Observations. 
the entire column between Sacramento and Summit will exceed 
the half sum of the temperatures at those two stations, by the 
uantities shown in column fifth of the above table. The 
ifferences of pressure due to these errors of temperature for 
the four lines in table III fot barometric maxima at Summit, 
are 
—036; —*'037; —‘053 and —°044. 
Subtracting these numbers from the numbers in column 
eleventh of table III the differences are 
—287; —‘185; —°102 and —-007, 
which are the fisbaepanibieg’ between theory and observation 
remaining to be explained ; so that twenty-three per cent of the 
iserepancies appear to be due to the error in the assumed tem- 
perature of the air sehr i about half of the cases, the | 
barometric maxima occurred at Sacramento at the same time 
as at Summit (that is, ‘within eight hours of the same instant). 
In two-thirds of the remaining cases, the maxima occurred first 
at Sacramento, so that the second cause appears to have only a 
slight influence at Summit. The main cause for these discrep- 
ancies appears to be the small range of the barometer at Sacra- 
mento, and the frequent want of correspondence between the 
_ barometric fluctuations at the two places. The following table 
shows, in ee of an inch, the mean range of the barometer 
at Summit and Sacramento for each month as derived from 
the observations of three years. 
' | Summit. Sacra'to.| Su.-Sa. | Summit. | Sacra’to.| Su.-Sa. 
January ....} 0°696 | 0°563 |+0°133)| July -.._..- 0°317 | 0°369 |—0°052 
February ---| 861 87 015 || August -.2.- 296 29 |— °033 
Pareto e 552 2 + °028 | September --| °456 05 }+ “051 
pr sos “660 565 }|+ ‘095 |) October __.- 540 525 |+ 016 
re RE epee “492 “430 |+ -062|| November __| °797 647 |+ °150 
JUNE ses: 421 377 |+ °044|| December.._} *711 ‘700 |+ ‘O11 
For the three winter months, the mean monthly range of the 
barometer is ‘043 inch greater at Summit than at Sacramento, 
whereas if the range was agetad opie to the mean pressure at 
the two stations, the Jan ge t Sacramento would exceed the 
c 
he peculiarities of the observations at these stations are 
best shown by a graphic representation. The accompanying 
cote plate I, shows the fluctuations of the barometer at Sum- 
it and Sacramento for the three months, Nov. 1870 and sam 
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