20 =. Loomis— Observations of the U. S. Signal Service. 
is obstructed in the valleys between the mountain eae 
that here the direction of the wind may be opposite to that 
which prevails above the mountains. 
If we attempt to trace the progress of storms across a 
Rocky Mountains by curves of isabnormal besuvenegs we hav 
no occasion to reduce the observations to sea level ; cones 
less, when we aim at great precision we find a difficulty rae com- 
paring mountain stations with stations at a lower level, inas- 
much as the barometric fluctuations generally diminish as we 
rise above the level of the sea. In order to find what correc- 
tion is due to this cause I determined the mean monthly range 
of the barometer at all the stations of the Signal Service west 
of the Mississippi river according to the published observa- 
tions (now amounting to thirty-five months). The following 
Mean monthly range of the Barometer. 
BIBISIS)/elelelelals 
t=] 
a a) a 2 
oe. ed ie Ben (mses at =a Be Me» ea Pk oo te Oe = 
Portland, Or. |1°15 |0°95 |0°82 |0°85 |0°62 |0°54 |0°3 5 04 
m Francisco|0°81 | ‘70| 51] +54] -37)| -41 Chis 
San Diego 0°46] °56| -41| -42| -31| -29| -27] -25| -35| -37| -45| -44] -38 
Virginia City |0°88 | *82] -66/ -61| °58| 51) °35/| -34] -66]| -66| -85| -86| °65 
Corinne EI ft 
93] °83} 96] 67] -47| 42] -35] 66] 60] -81] 77] “72 
ry “I1| “16) -71| 64] -48| 42] -40| -69| -71] -79] -75| “65 
Salt Lake City] ‘77 | “69] "75| -39]| -48| -53| -36| -32] -66| ‘79 /1°00| -84] °63 
De TT] *81| 77] 69) -54| -46] -43] -76] “72| 84] -76] “70 
nton 1°23] ‘92} -99/1-0 62| -68| -63|1-01| °87-/1-22 |1-00| 92 
Bismark 1-17] -97 [1-14 |1-29| -8 30 [1°84 |1-44 
t. Sully [50 |1-37 [1°45 [1-13 |1-11 | 90] -90} -82 [1-16 |1-24 |1-21 [1-31 
Yankton 44 |1-38 |1-34|1-13 |1-03 | -80| -76| -69 {1-15 {1-13 |1-41 [1°15 [L-12 
1-39 |1-37 |1-09} -91] -71| -71| -57| -87 |1-05 [1-39 [1-16 
North Platte |1°41 1-30 {1°25 |1-10| -78 1-29 |1-65 [1-13 
1-45 | °86 {1°29 |1-0 88 1-10 [1-33 |1-11 
Pembina 1°45 1°27 1-25 |1°07 [1-08 | -80| -78| -73/1-06 |1-00 {1-36 [1-32 [1-10 
Duluth 1°35 |1°38 |1°24 |1°12 | -95| -98| -67| -63| -88 1-11 1-44 [1-33 [1-09 
Breckenridge |1°42 |1°32 |1°34| -99|1°11| -87| 76) -62/| -97 |1-18 |1-42 [1-32 |1-11 
St. Paul 1-27 |1°39 |1-34| -92 80| °63| °61) 91/1712 [1-34 |1-29 |1-04 
Crosse 20 {1-43 1-25 | -95| -87| -75| -63| -59| -84 {1-14 11-30 |1-34 [1-02 
Dubuque 1714 }1°32 |1°24|1-06| -75| -66| -65 1 1 
Davenport 14 |1-44|1-21 | -99| -77| 61 | 55} -55/ -73}1-00 [1-32 [1-17 
Leavenworth |1°30 |1°34 [1°25 |1-07 | -77| -61| -61] -53/ -82| -97/1-29 l1-13| -97 
St. Louis 1-17 |1°20|1°19| -94| -71| -56] -51| -55| -67| -84|1-22 |1-08| -89 
Cairo [14 |1°02 {1°16 | -91 2| -45| -45/ -48| -70|1-07| -s9| -78 
Ft. Gibson [1-28 {1°06 |1°04| -95| -77| -49| 54] -46| -63| -91 1-11 |1-02| -86 
Memphis 105 | -97|1°01| -88| 58} -45] -43] -38| -43| -59/10 13 
ae 
23 yeaa 
* 
