6 
REMARKS ON METEOROLOGY AND BAROMETRIC RESULTS. 
between Cape Mendocino and the mouth of Columbia river, within the accumulative influence 
of the return trade winds of the Pacific. 
The mean of seven observations with air temperature of 58°, taken by Lieut. Michler at 
New Town, San Diego harbor, to which the same corrections for the various elements of error 
as used in the above work, were applied, gave for the height of mean tide 30.018. From the 
above results we have the following table, uncorrected for gravity, and contrasted with a portion 
of Schouw’s table for the North Atlantic ocean. 
cific. 
Atlantic. 
Latitude. 
Latitude. 
o / 
O 
38.00 
30. 057 
45 
30.011 
37.20 
. 30.040 
40 
30.006 
35.10 
30. 031 
30 
30 069 
34. 27 
30. 023 
20 
30. 004 
32.40 
30.018 
FROM FORT YUMA TO FORT FILLMORE. 
To obtain the corrections for the temperature of the mercury above 100°, the formula given 
in the Smithsonian tables, prepared by Professor Guyot, was used. The correction for constant 
error was obtained by mutual comparisons of barometers 392 and 790, (Green’s cis.,) and with 
the Smithsonian standard at Green’s instrument depot, New York city. Frequent observa¬ 
tions were taken to determine the horary correction between Fort Yuma and Fort Fillmore. 
The corrections are given in Table No. 3, and constructed in Plate 1, figure 4. A peculiarity 
was observed in this phenomenon, which will he adverted to in the sequel. 
To determine the measure for abnormal oscillations of the barometer, a sufficient number of 
observations along the line of survey or in the contiguous regions could not be obtained with 
which to compare. The observations at San Diego, however, • were compared with those of 
Lieut. Michler, at Fort Yuma, during the months of December, 1854, January, and part of 
February, and, with those of our own, in June, 1855, and gave very satisfactory results, and from 
this comparison a scale of corrections was obtained for that place. By reference to the diagrams 
it will be seen that the fluctuation of the atmosphere occurred very nearly simultaneously at 
those places, and, consequently, an accurate measure for the abnormal error was probably 
obtained. For the months of December, January, and part of February, the average amount 
of correction was found to be wmiws0.180, and for the middle of the month of J xmeplus 0.100. To the 
observations of Lieut. Michler the former correction was applied, and gave for the height of his 
astronomical station No. 1, opposite Fort Yuma, 35 feet above the surface of the river 310.8 
feet, and for the level of the water 275.8 feet above mean tide at San Diego. At Camp 60, 
(Gila river,) about 7 miles above the junction of the Colorado and Gila rivers and about 20 feet 
above the water, 52 observations were taken, to which were applied the latter correction for 
abnormal error, and gave for the height of the Gila at that point 296.6 feet above mean tide at 
San Diego. Four observations at Ankrim’s ferry, about one and a half miles below Lieut. 
