PLAN AND ESTIMATE FOR DETERMINING LATITUDES AND LONGITUDES. 541 



observed quite frequently while en route, and thus serve as checks on the chronometric longitudes. 

 As the long stay at the principal stations will afford the means of obtaining excellent observations 

 for the rates of the chronometers, it is believed that the position of every camp may be deter 

 mined with a near approximation to the truth. 



Occultations are of rare occurrence, and it can hardly be expected that more than two, possibly 

 but one, can be observed during a lunation. 



At each principal station, extended series of latitude observations with the sextant should be 

 made ; and also the latitudes of the camps en route be determined. 



The requisite instruments are in store at this place ; consequently no outlay for instruments is 

 needed. The party should contain, besides an assistant, three packers and a cook. The princi 

 pal expenditures would be for the services of the members of the party, their subsistence and 

 transportation. 



With a small appropriation, therefore, these observations can be made, and their value cannot 

 be overrated. Although a list of longitudes might have been obtained on our route hitherward, 

 the rapid marches and all the circumstances of the movements of the train were such, that good 

 results could not have been secured. With an appropriation enabling the carrying out of a pro 

 gramme similar to the above, I think such positions can be determined as will answer for the 

 ground-work of a map published in the year 1855, and which will not be materially corrected by 

 future explorers who may visit these points. 



I have estimated $5,500 as the total cost of the proposed operations. 



From Fort Benton I would propose, as the chronometers kept tolerable rates from the Missis 

 sippi to this point, to descend the Missouri to St. Louis, stopping to occupy Fort Union as a per 

 manent station, and making the usual camp observations all the way. Afterwards, I would 

 propose to visit Sauk rapids, and occupy that station. By this arrangement a great expense 

 may be saved, and every object be effected. Should a steamboat be chartered for the Blackfoot 

 council, I could probably connect with her at Fort Benton ; otherwise a row-boat can there be 

 obtained in which to descend the river to the settlements. 



I have made the following programme of the periods to be allotted for the occupation of each 

 station as far as Fort Union. The distances separating them can be easily made in the times 

 intervening : 



At Wallah -Wall ah, from April 20 to May 10. 

 At Pend d Oreille lake, from May 20 to June 2. 

 At St. Mary s village, from July 17 to August 6. 

 At Fort Benton, from August 16 to September 5. 

 At Fort Union, from September 18 to October 5. 



Should the appropriation asked for be made, it is to be hoped that I may be able to reach 

 Wallah- Wallah at the time above specified ; otherwise another lunation must be awaited. 



It is indispensable that a portable observatory, with a stand for transit, should be carried along, 

 as at none of the stations proposed to be occupied for an extended series of observations can the 

 proper materials for their construction be procured. A stiffly braced frame, with roofs, sides, &c., 

 of water-proof canvass, may be made, which will not be very difficult of transportation. 

 Very respectfully and truly yours, 



GEO. W. STEVENS. 

 His Excellency I. I. STEVENS, 



Governor of Washington Territory. 



