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Show 14 BMlGl'tAN.T'5 riUIDl. ' . . rid e bas arisf'n from inattention to vers of Louisiana flow u.po~ a J d gd '·n th .... delta has su little incH-their depth. The country m~ u:· o~ from the gravity and impul:se nation, that. the water ca.~ on~ the surplus, after escaping from the of the ~upermcumb. ent mfia sds.. agn an . d' t l I rests and acou- 1mme 1a e eve , channels of the n.vers, ln dill These are the true causes of the in· mulates on . the aJJ3cent an · undation. . b d f water in the Mississippi has The rapidity of the enhre t~ y fi~e or six times its real motion. been also oYerrated, to more an son rna be convinced, who That this error has been made, .every per . y . our books of ~ It the vanous accounts, g•ven m will care u y comp~re . h th f e that actually elapses brtween geography and trave s, wit e Jm heads of the Ohio, Mis¥ the br~aking u~ of t~e snows towards t~; the water over the delta sissippl and 1\IJssoun, and the passage h [! 11 . table in order to the gulf of Mexico. I have ct.raw~litm:t:.., o~~r::f which flow the to exhibit the lengfth handM.re~p~cb~~ and to iliustrate the causes that various branches o. t e Jss~sslpp• '. produce, and the seasons of mundahon. lf1 s ~ ~ . e.£~ ell i> ~ o·- ~ .... ~ lf1 ..... _..,~.p~.. ~;::,:.lo .m.... •.::) .~ rn ~·,....... .c .... C/l .....- ~ -~ ~0~ ~u H.cd river ArkaHsaw White river I Ossage Kansas Platte Missouri Yell ow stone Bighorn 1\'lississippi' Illinois '¥abash 'fennessee Qhio \ rn 1 ~~ S· ~ ·:--.;S ~ ...... .So ...... 0 .... ~ cO t) ;S .~ ~ p. .s s .8-- .~ 0 ~ ~ ...~.... ·-C/l 500 650 650 1350 1550 1800 1.200 5050 3300 1.200 1.215 1150 1050· 1000 l . 1 .~ ;S ~ ;:::l I; So ·-. ...... s~p .. 0 ;S .9- s C/"1 rn ..'.f.). 4.> 0 rn u :....~ §'";;:S rn ~ ~ ·~-~u .s 0 ...... rn 0 1.750 2500 1500 2100 S400 .2900 4000 5900 5800 ~300 1700 \ 1650 1750 S.200 56,050 ;S ...... 0 ~ ""den ;:::l ~ .... ..... .,C) ~ .... ;:::l cd 0 ' Hcn I c . ..... Q) ~ ~ ;S s, ~ CJ ...... 0: c 'S ~ 0 .Cu ~ Ul rn C ~.8 £~ cd""d ~ c OO::l 41 oN. March y y y 37° N. \ ~'ebruar 36~ N. Fcbruar 36Q N. Fcbruar 40° N. March 4.2° N . April 45° N. April 43° N. Apr~l 4.2° N. April 48° N. May 4.2° N. April 41° N. May 51° N. Februa, 4.2° N. March I The times of the year when the various streams com~enc~ tLe i~ grreatest flood, as stated in the .tabl~, are merely approximate; considerable 'variances take place m different Y.ears. In the years .180() and 1801, the Mississippi did not overflow 1ts banks. The ordmary time of extreme high water is at. Natchez, the fifte~nth of June; an~ at New Orleans the first week m July. Calculating the velomt.r: 0 the water in the., various rivers by the dt·s tance an d ti·m es of fl.o wm.r.or ftom their sources1 the Jneqiulij motion falls ~bort of 20 mlles 1n \ EMIGRANT'S GUIDE. ~\venty-four hours. The lower waters of the Ohio drains out in February, but those of the Monongehela, Alcgbany, Muskingum and Kenhawa, do not reach in common years their height, before tbe first of March. The distance from the mouth of Kcnhawa to Natchez is nearly 1300 miles. The waters in passing over this space occupy about l 00 days. . The current, as it is usually understood, is the motion of the upper part of the stream. A boat floating only during the day, or one half of the time, will, by taking advantage of the cu~rent, always pass the apex of the flood. The motion of the current, and entire mass of water, differ in all rivers; in that of the Mississippi, the rebtive difference of b to 1, would perhaps be but little variant from the reality. From an inspection of any good map of North America, it will at once appear, that from thei:r position, and from the various climates they traverse, that th.e waters of all the branches of tlre Mississippi must drain gradually. The fact is consonant to the theory. Therefore if the motion of the b0'-~Y of water was not very slow, no inUl'ldation of the delta of the Mic;sissippi could happen, as there would not be time for an accumulatiou to take place. There are few !'Ubjects where correct opinion would lead to more beneficial conS€quence!!, than respecting the floods of the Mississippi . If the inhabitants could be made sensible of the true causes of the overflow, it woulu prepare their minds to consent to the adoption of more effectual preventives, than any that they have yet attempted. . To gain clear conceptions on this subject~ it is necessary to con~ ·der the water at the time of the highest flood, as in reali1y divided 1 ~1to three parts; th~t part which flows in the natural channels of the nver~; that which composes· the overflow ; and that part which lies stagnant in Jake.s, ponds and the inunuated bottoms. , Of the surch~rge from the .Mississippi river, fot.n-fifths ]eave that stream by the efflux of the Atchafalaya. The latter ri,·er is 111 yards wide, where it leaves the former, and its extreme depth 1' 5 or ~0 feet.. Thro~gh this passage no water leaves the Mississ ippi except m the time of fresbes. At its efflux, the current of the Atcbafalaya is very rapid, but gradually abates as it proceeds in it5 course, and as~umes, about ten or twelve miles from the .Mississippi, a motion not essentially differen ~ from the latter stream. After the Mississippi Hoods have fallen beneath. the o:dinary banks, the AtchafaJaya becomes completely stagnant m all Jls length. Often the tides, though never more than 2-f ~r. 3 fe~t in the gulf of Mexico, flow up the Atchafalaya within th1rty miles of its efflux. The author wa13 ~n eye-witness to this effect in the years 1807, 1808, 1809 antl JCJO. fie also saw with pleasure and astonishment, in October, 1808, at the lower extremity_ of the large raft, the water of the AtchafaJaya extremely transparent. Tbe change from the turbid appearance of the str~C a.tn in the spring and summer of the same year, was reaJiy striking. The limpid tate of the water arose Jrom its remaining a considerable time tq. tally tranquil. A few days reverc:ed the scene ; the Mississippi OYer· flowed in t.bc latter part of October ; in N. ovembe r7 eJ.:ces5i 'ta: r~~ns |