The following is taken from Notes of a Military Reconnoissance..., by William H. Emory. Spelling and punctuation are as they appear in the original.
To Col. J. J. Abert,
BUREAU OF TOPOGRAPHICAL ENGINEERS,
SIR: You will repair, without delay, to Fort Leavenworth, and report yourself and party to Colonel Kearny, 1st dragoons, as field and topographical engineers of his command. In addition to yourself, the party will consist of---
First Lieutenant Warner, now at Washington;
Lieutenant Peck is a West Point, but he has been ordered to repair to St. Louis, and report to you at that place. Should Colonel Kearny be at St. Louis, which you will ascertain on passing through that place, you will report to him at St. Louis.
J. J. ABERT,
Colonel Topographical Engineers.
To Lieut. W. H. EMORY, Top. Eng.
Anticipating that the route of Colonel Kearny's command would be through unexplored regions, your suggestions required, that in all cases where it did not interfere with other and more immediate military demands of the service, the attention of myself, and the officers assigned to duty with me, should be employed in collecting data which would give the government some idea of the regions traversed.
The column commanded by Colonel Kearny, to which we were attached, styled "The Army of the West," to march from Fort Leavenworth, was destined to strike a blow at the northern provinces of Mexico, more especially New Mexico and California.
It was supposed we would barely reach Fort Leavenworth in time to join the army, and but twenty-four hours were allowed us in Washington to collect the instruments and other conveniences for such an expedition. This was quite sufficient for all the objects appertaining directly to our military wants, but insufficient for the organization and outfit of a party intended for exploration. In submitting the following notes, they should be received as observations made at intervals snatched from other duties, and with an expedition whose movements were directed by other considerations than those which would influence the views and conveniences of an explorer.
We left Washington on the 6th of June, unable to procure a pocket chronometer, or telescope of power sufficient to observe eclipses; but through your intercession, and by the kindness of the Chief of Hydrography, U. S. N., we were provided with two excellent box chronometers, No. 783 and No. 2,075, by Parkinson and Frodsham, and we received from the bureau two of Gambey's 81/2-inch sextants.
Crossing the Alleghanies the stage capsized with us, and placed the chronometers in great danger, but the prudence of Mr. Bestor, who carried them in a basket on his arm, saved them from destruction. Their rates were changed very materially by the accident, but on reaching Fort Leavenworth, the chronometers were again found to have changed their rates materially, owing to the peculiarly unsteady and jarring motion of the steamer upon which we ascended.
The meridian of Fort Leavenworth, as determined by Mr. Nicollet, is therefore taken as that to which all the determinations of longitude as far as Bent's fort, by the chronometer, are referred, and any change which subsequent observations may make in the longitude of Fort Leavenworth, will be common to them. The travelling rates of chronometer 783 were, as the observations will show, very uniform, and longitudes deduced from it, compared with direct measurements of lunar distances made at various points, give satisfactory comparisons as far as camp 70, October 9th, on the Rio del Norte. At this point we left the wagons, thence crossing the mountains to the Gila river, some irregularity in the rates is discoverable, until we reach camp 83, October 26th on the Gila river.
From that point (camp 83) to San Diego, on the Pacific, the rates were very uniform. Assuming Captain Belcher's determination of that point, 7h. 48m. 44s., west from Greenwich, and carrying my longitudes back, they compare well with the longitudes derived from the direct measurements of lunar distances made at different points of the route.