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Show .. t1 1 e scene o f as tl.0110m1·cal or barometrical observations, furnish the. m. a. te~ rials out of which this map bas b en constructed. Nothing supposlltltous has been admitted ll!}Oll it; so that, COllllecting with Captain vVllkes's survey of the mouth of the Columbia, aml with the authentic smveys of the State of L\lissouri, it fills up tltc vast geographical cha~m bet w ~en these two remote points, a.ntl presents a counected aud accurate view of our rontinent from the J.VTississippi river to the Pacific oceau. To this gcographicnl map, delineating the face of the country over which we travelled, there is added. atioth cr in profile, showi11g the elevations, or the rise all(l full of the country from the Mississippi to the Paci f1c. East of the Rocky mountains, two of these profile views are given-one from St. Louis to the South Pa~s, the other from the month of the Great Platte to the same point. The latter is the shortest; atHl following, as it docs, the regular descent of the river, and being seven hnndred miles west of the Mississippi, it may be that the eastern terminus of this line may furnish the point at which the steamboat ami th e steam car may hereafter meet and exchange cargoes in their magic flight across this continent. These profile views, following the travelling routes, of conrse follow the lowest and levellcst Jines, aud pass the mountain at the point of its greatest depression; but to complete the view, and to show the highest points as well as the lowest levels, many lofty peaks are ske tched at their proper elevations, towering many thousands of feet above the travelling line. It may here be excusable. to suggest that these profile maps here exhibited are, perhaps, the most extended work of the kind ever constructed, bei11g from St. Louis (according to the route we travelled) near sixteen hundred miles to the South Pass; from the mouth of the Great Platte to tile same Pass, about one thousand more ; and. then another sixteen hundred from that Pass to the tide water of th1~ Oregon; in all, about four thousand miles of profile mapping, foundeu upon nearly four hundred barometrical positions, with views sketched aud facts noted. in the field as we went. In the departments of geological aud botanical science, I have not ventured to ad vance any opinions on my own i111perfect knowledge of those brunches, but have submitted all my specimells to the enlightened judgment of Dr. Torrey, of New Jersey, auu Dr. Hall, of New Yt r.Jc ' who have killdly classified awl arranged ull that I was able to s11bmit to · them· The botanical observations of Dr. Torrey will be fnrnish cd iu full hCI'eafter, there not beiug time to complete them now. The remarks of Dr. Hall, 011 the geological specimens furnish ed to him, will be found in an append ;x to the report; and to his palreo ntological skill I am indebted for the discovery of an oolitic formation in the region west of the Rocky 5 mountaiu ~, which f11rtber examiuatioti may prove to assi milate the geo,ogy of the New to that of tho Old "Vnrkl in a rare particular, which had not before beeu discovered in either of the two Americas. Unhappily, much of what we had collected was lost by accidents o[ serious import to ourselves, as well as to our animals and collections. In the gorges and ndges of the Sierra Nevada, of the Alta California, we lost fourteen horses all(l mules, falling from rocks or precipices into chasms or rivers. bottomless to w; and to th elll, and one of tlJCm loaded with bales of plant~ collected on a line of two thousand tlliles of travel; and, when almost home, our camp on the banks of tltc Kan as was del uged by the great flood which, lower down, spread. terror aud desolation 011 the borders of the Missonri anrl l\Iississippi, and by wlticll great damage was done to om remaining perishable spe~;imeus, all w •t anu sat urated with water, and which we had no time to dry. Still, what is saved will be some rcspectaule co11tribmion to botanical scicllcc, thanks to the skill and care of Dr. Torrey; and botb in gcolog~r a nd botauy the ma p~ will be of great value, the profile view showing the elnvatious at which the specimens were fouud , at td the geographical 111~p ~hawing tlte localities from which they come. The a:-;tronou1ical obsc rvn.tiolts, t;:lkell with good instruuw11ts, IJave been tested, where tltey were m o~t illlportaut, by a tllrec-folcl COilllHitation : ouc by Professor Walker, of Philadelphia, who.::;e a~tronomical n~putatio11 i., ~o great; anorher by l\[r. .Joseph C. Ilubbard, a promi ·iug youug mathematician frotu Cotulccticul; the third by myself; so tbat the corrcctn cs~ of the lougitudcs ami latitudes may well be rclieu upou. lu sketchiug the topog rapiliL:n.l features of the co untry, a braud1 of' tlcieuce in which he had been professionally ed ucated, L\Jr. Clwrlrs PrNl:,:.. had beeu my assistn11t it1 both cxpeuitiom;; and to llis extrao rcl ittLJry sl<il l, supported by the pleasure he felt in tltc exec ution or his duties, J aut indebted for tlw continuous topographica l ske tcltcs of the n!gious throu!.;h which we pas~e d, and which were 11evcr interrupted by auy extremity of fatigue or privation. The uaromctricul a nd metcorolon·ical oG:-.wrvatious were carefully tt tr•dr. with good iustrutnents, and admit of uo mate rial error Geyoud. the lUllllllc dev iatiotts iusoparablc frot11 sucb opcratious. Tbc third cxpcuiti ou, IJOW commeucitJg, is uttderta keu with more ample ~ne.aus tiJ an the two fonucr; a ud, being dircelcd to a region so illtCrel-Stlllg m Itself, and so new to science, can hardly fail to TClJllitc the en terprise which explores it. Tbc report, or 11 a rrali ve, of tit is cxtc11dcd cxpeditiou, like the lllap ... wllicl1 illn 'lmte it, will be 1-ltrictly confined lo what wa · seeu, and to what is necessary to show tlte 1~tcc anu character of the country, and to add .. ,. |
