SR pel ee ee RO Te Se) aE ae he ey a OR EEN Ore he 
Hija apace i 
Se ea 
gi 
BE. Loomis—Contributions to Meteorology. 17 
in the Annual Report for 1879 of the mean barometric heights 
for all the stations of the Signal Service without reduction to 
1000 feet, and for which the mean heights of the barometer are 
given for a series of years. Column Ist shows the name of 
the station; columns 2d and 3d the latitude and longitude; 
column 4th the elevation in feet as assumed by the Signal Ser- 
vice; column 5th the mean height of the barometer for the 
entire year, as given in the Report for 1879, page 451; column 
6th shows the mean temperature of the station; column 7th 
shows the mean temperature at sea-level under the station, de- 
termined in the manner described in my 12th paper; column 
8th shows the mean height of the barometer for each station 
at sea-level. ‘These numbers were determined in the following 
manner. For all stations whose elevation was less than 1000 
feet I took the mean height of the barometer according to the 
reduction adopted by the Signal Service; and for stations ele- 
vated more than 1000 feet I made the reduction according to 
the elevations as I had previously determined them. I took 
the mean barometric heights for all the meteorological stations 
of the Dominion of Canada, so far as they are published in the 
official Reports. For various additional stations in the vicinity 
of the United States, I took the barometric heights from 
Buchan’s Memoir on the Mean Pressure of the Atmosphere, in 
the Transactions of the Royal Society of Edinburgh, vol. xxv. 
These numbers were all represented as accurately as possible 
by isobars drawn upon a chart of the United States. This 
chart is exhibited upon a greatly reduced scale on Plate [. 
From this chart the most probable mean pressure for each sta- 
tion was derived, and the results are given in column 8th of 
the table. Column 9th shows the altitude of each station com- 
puted from the data here given according to Guyot’s Tables; 
and column 10th shows the altitude computed from William-— 
son’s T'ables which are founded upon Plantamour’s formula. 
The height of Pike’s Peak was obtained by computing first its 
elevation above Denver from the observed values of the pres- 
sure and temperature at those stations, and adding this result to 
the height of Denver computed from the data contained in the 
table for that station. 
The height of several of these stations has never been deter- 
mined by direct measurement so far as I have been informed. 
If we compare the heights of those stations which have been 
thus determined, as reported in Gannett’s List of Elevations, 
we find them to accord reasonably well with the results above 
given as computed from the formula of Laplace. If we take 
Am. Jour. caiotinene Sertgs, Vou. XXII, No, 127.—Juxyv, 1881, 
