E£. Loomis— Observations of the U. S. Signal Service. 91 
Columns 2 and 3 show the latitude and longitude of the 
stations named in column 1; column 4th shows the elevation 
of the stations above sea-level as assumed by the Signal Service ; 
column 5th shows the mean temperature of each station for the 
month of January according to the observations of five years; 
column 6th shows the temperature at the level of the sea 
directly under each station, estimated in the manner already 
described ; column 7th shows the reduction to sea-level adopted 
by the Signal Service; column 8th shows the reduction to sea- 
level computed by Dunwoody’s Tables contained in the Annual 
Report of the Signal Service for 1876, pp. 854-360; column 
9th shows the mean pressure for each station as deduced from 
the Signal Service observations, and column 10th shows the 
mean pressures corrected by the reductions given in column 8th. 
If now we attempt to represent by isobaric lines all the 
observations at the Signal Service stations for the month of 
January (employing for the Mountain stations the values given 
in column 10 of the preceding table), we find that nearly all the 
observations can be well represented by curve lines which have 
a tolerably symmetrical form. There are only four cases in 
which the discrepancies amount to as much as 0:05 inch, viz: 
Virginia City, Santa Fé, North Platte and Dodge City. 
he result above found for Virginia City indicates a probable 
error in the assumed elevation of that station. According to 
Hayden, the height of Virginia City is 5,824 feet ; according 
to DeLacy it is 5,778 feet: and according to the Signal Service 
it Is 5,480 feet. The mean of these three determinations is 
5,694 feet. Assuming this to be the true elevation, the corrected 
pressure becomes 30°15, which accords pretty well with the 
observations at the other stations. 
According to Wheeler the height of Santa Fé is 7,047 feet, 
and according to the Signal Service 6,862 feet. Assuming the 
true elevation to be 7,000 feet, the corrected pressure becomes 
30°14, which accords tolerably well with the observations at the 
other stations. 
The results at North Platte and Dodge City appear to be 
about 0-25 inch too small. These discrepancies cannot reason- 
ably be ascribed to error in the assumed elevations, but they 
are apparently due to an erroneous mode of reducing the obser- 
vations to sea-level. If the observations at these stations as 
pe aished in the International Bulletin are reduced to sea-level 
¥ Dunwoody’s Tables, the results will be found to agree pretty 
well with those at the neighboring stations. I then drew the 
isobars which best represent all the Signal Service observations 
for the month of January, including the four stations above 
famed, with the corrections which have been indicated. These 
curves exhibit an area of high pressure for the central part of 
