TABLE III—Continued.

Difference of longitude between Frontera and San Elceario, by flashes of gunpowder, made on the

TABLE III-Continued.

Difference of longitude between Frontera and San Elceario, by flashes of gunpowder, made on the

The record of the flashes, to establish the difference of longitude between Frontera and San Elceario, is given as a means of determining the weight to be attached to this mode of observing. Assuming the result to be correct, it gives a very satisfactory coincidence between the results obtained for longitude at Frontera and San Elceario, by moon culminations, by two independent positions, with different instruments and different observers.

The record is omitted for other stations, but the results are given in the following table:

TABLE IV.

Recapitulation of differences of longitude of several astronomical stations on the Rio Bravo, found by flashes of gunpowder.

Long. of station near Presidio del Norte, computed from observations with transit, by W. H. Emory.

TABLE V-Continued.

Comparison of results for longitude of station near Presidio del Norte, for each date of observation, as computed with Tab. R. A. in Nautical Almanac and Greenwich observations.

Comparison of mean results for longitude, obtained from observations on moon's li.nbs, as computed with Tab. R. A. in Nautical Almanac and Greenwich observations.

FIRST.

Mean of results of observations on moon's first limb, computed from Tabular Right Ascensions in Nautical Almanac.
Mean of results of observations on moon's first limb, computed from Greenwich observations..

Difference, or Greenwich observations + Nautical Almanac...

SECOND.

Mean of results of observations on moon's second limb, computed from Tabular Right Ascensions in Nautical Almanac.
Mean of results of observations on moon's second limb, computed from Greenwich observations.

Difference, or Greenwich observations + Nautical Almanac....

h. m. S.
6 57 18.96

6 57 40.11
+ 21.15

...

6 57 20.94

6 57 37.93

+ 16.99

Corrections to be applied to results obtained from computations (with tabular R. A. in Nautical
Almanac) of observations made near Presidio del Norte.

!

TABLE V-Continued.

RECAPITULATION.

Difference of results for longitude of station near Presidio del Norte, as obtained from computations of observed moon culminations, with tabular R. A. in Nautical Almanac and Greenwich observations, 1852.

Tabulation of results for longitude of astronomical station near Fort Duncan, derived from observations made with 30-inch transit (by Troughton & Simms) and sidereal chronometer No. 2440, (by Parkinson & Frodsham:) By J. H. Clark, under the direction of Major W. H. Emory, Chief Astronomer and Surveyor of United States and Mexican boundary survey.

By giving double weight to the results of observations on moon's 1st limb, we have longitude =6h. 42m. 01s.78

Longitude of astronomical station near Fort Duncan = 6h. 42m. 01s,78