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 4?TH AND 49TH PARALLELS. 



OLYMPIA, 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 rny 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 j nevertheless, they will give very fair results. They may be 



