Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean: Vol. 1, Pt. 2

PLAN FOR DETERMINING LATITUDES AND LONGITUDES.
expedition could be carried on, it does seem to me that, upon a proper representation being made
to the Hon. Secretary of War, he must necessarily see the great advantage flowing from it.
I have estimated that a sum of five thousand dollars will thoroughly and efficiently organize
the party, keep it in the field, and cover any and every expense attending it under the most
unfavorable circumstances
Considering, therefore, the great ends to be accomplished, I would most respectfully lay before
you this letter for your consideration.
Truly, your most obedient servant,
J. MULLAN,
Lieutenant U. S. Army.
Governor I. I. STEVENS.
REPORT OF MR. GEORGE W. STEVENS, SUBMITTING A PLAN AND ESTIMATE FOR DETERMINING
WITH ACCURACY THE LATITUDES AND LONGITUDES OF THE PRINCIPAL STATIONS ON THE
ROUTE NEAR THE 47TH AND 49TH PARALLELS.
OLYMPIA, W. T., December 21, 1854.
SIR: In the progress of the main train of the Northern Pacific Railroad Exploration and Survey, it was intended to make,. at several of the important points on the route, observations of
moon. culminations with the transit instrument, for the accurate determination of longitudes; but
on taking the field it was found that marches must be made with far greater rapidity than was
anticipated, and that time would not admit of this instrument being set up for a sufficient length
of time at any of the proposed stations. Throughout the whole route, the sextant was used upon
every favorable night for the determination of time and latitudes. The latitudes thus secured
are good throughout, and the chronometric longitudes might be made of use had we accurate
determinations of the principal stations from which to check them, The method of lunar distances was not made use of, from the knowledge of the fact that the best observations give but
inferior results, and my own limited experience would not authorize their attempt. Nor was the
astronomical party supplied with a telescope suitable for observing the eclipses of Jupiter's satellites and occultations of fixed stars.by the moon.
Could the route be again traversed with a small party under my direction, whose. movements
might be entirely independent of those. of -a large train with other duties to perfor, and the
transit established at the principal stations during at least one lunation at each, not only might
the stations: so occupied be determined with close approximation to the truth, but the observations at intermediate camps made on our way from the Mississippi might be brought into use.
Olympia has been occupied during the past summer as such a station, and the observations
made, whenever the weather would permit, give a good determination for this point.
I would most earnestly ask that the opportunity may be afforded me of recrossing the northern
route, and I would submit the following as a programme of operations, which would serve the
requisite ends:
To occupy Wallah-Wallah, Pend. d'Oreille lake, (its eastern extremity, where the Clark's fork
enters. it,). St. Mary's village, Fort, B~enton, Fort Union, and S~auk rapids, our point of departure
from the Mississippi, as transit stations.
At each of these stations, besides. the observations of moon culminations, observe all the occult-.
ations available, and eclipses of Jupiter's satellites. The longitude determined by an occultation
is deemed more reliable than by the other method, when made under favorable circumstances
and made in connexion with transit observations is particularly valuable. In so high latitudes as
those of this route, the atmosphere is not so favorable for observing the eclipses of Jupiter's satel
lites as in the lower latitudes; nevertheless, they will give very fair results. They may be
540