540 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. 
Ouympia, W. T., December 21, 1854. 
Sir: In the progress of the main train of the Northern Pacific Railroad Exploration and Sur- 
vey, 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 dis- 
tances 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 satel- 
lites 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 perform, 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 observa- 
tions 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 Benton, Fort Union, and Sauk 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 
