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Show E ~VHGRAN'f'S GUIDE. gara, it is st ill_ so temperate? that col~ conti~ues o1ily t~vo mouth_s with any cousHierable se \'enty ; notwtlhstand •ng that th1s. pl_ace 1s the most elevated part of the Plateau, or tab le Janu. This c~rcumstance totally deranges the rule formed from the comparative le vels. " The descriptions that have been made to me of the cold of Vermont, of New-H.unpshire, dl>es not corre pond with the seasous in Gene 'e ;~ but rath er with that of Phi ladelphia, 3° farJher south. lt b:1s been remarked, as a singular circumstance, that, in the latter to n , frost occurs in every mu~ltb of tl1e year, except July; and that ou the Wt"! tern side of the mountains, a similar circumstance does not take pl ace ~o uth of the village of Oneiua in Genesee,t at the 43() north b titLide ; whilst at Albany, east of the mountain··,+ it freezes every month in the y ear, and neither peaches or cherries can ripen. "Before procee J ing further in this inv estigation, it \rill be necessary to add some ob~ crv a ti o n s , and to observe some preparatory to a more com ple te J evc lopement of the assumed theory. 1 " 1. l t re.- ults fro n the comparison I have presented, that to measure accu ratdy tbe dcrrrees of temperature existiog in different parts of the LJn'ted States; two vast thermornetrical scal~ts must be applied to the whole country, rossing each other at right angles. The one pL ccd along tlle rn er iJ ian line, having its maximum of cold towards the pPJe, say on tbe river St. Lawrence, and its maximum of heat to· warJs the tropics, ~ y in Florida; between the two extremes, the heat increa s 1~s or decreases r gular1y, according to the latitudes, the level anj e ~ p v::u re bei ng equal. '!'he other scale placed transversely n11d the ri ch :1llnvial bottoms of Ohio river, but what must be p111.ssed in a sul'· "ey oi' Lhe ~otw try undet· re vi ew. Tbe pro uction :; of the ea.rtlt arc not Jess val"'ied than its sur-face; the nume- 1\."lus specie" o f veget11bles and min e1·als that have been provided IJy naturef~r t he u.e of man in thi;, unequ11 lled valley, justly claims tbe attention and admirat ion of t ite trav eller and geographer. It may be also remarked, that amongst the n1in crnl prod uds, tllose most absolutely uecwssa1·y are most abundant; salt, irun , coal , anJ cnrl.Jonale of lime. It is also roode1·ed possible that to those will b~ addetl gyp urn ; and that the three former exist iu much greater quan· tity than has been t,!C nC!'!llly thought. * lt would he sin guln.1', indeed, if the climatP. of Genesee was similar t() that of nitht" l' Vcl'mont or Ne w-Harnpshii'C. The grea test pm't of the tw? la ttf' t' plnces lie nortl of the fonner. GHnesee is a level country in the vt· ei uity of two la t' ''e lakes; Vermout and New-Hampshire are mountainous. Proxi mity to water tcuu · to equa lize the tempe ratm·e of the circurujacent air ; r,ou~ P q mmtly, tbe clim ate of places ne ar the Canada lakes, are, in every othe1· ri rcumstance, equal. mure moderate in wint er than of places more remote. t I nstances hnvc been knnwn to occur of fro st at Philadelphia, even in July, ac,; was t h1, case iu that month, 1816; but the author of th is note has been Wit· ue's to a l:i imilat· cold at the same season of the year at YV ashin gton in Penn· :.-y lvania, and what will sct>m pe1·haps more extraordina1·y, bebeld colton de· ~t i'Oycd by fl'ost at Na tchez September, 1804. ~ All 10.ny is in purt west of all the mountai ns, and only 1200 feet below the PXlrf!me d cvation oft he ce ntr·al table land . •.xcept th ~ space occupied by the • ·o1·th o1· HuuuJil riY et·, Albany is cov('rf'd by two chains of mountains from the sonth winds. Catsk ill mounlains, nrar 3000 feet uigh, is in full view fr·om Alb~ny to the southwe.>t. As to tbe ci1·cum. tance of (;herries and peaches not n· pc.niug at 1\IIJ~lny, the statem P-nt is totally incorrect; few places in tl~e worl~ 'llerc 1hose 1ru ,ts arc mot·c abundant than at Hudson Athens, IU.unebeck, · LBt. ~n: , Troy, and Lar:siug. l.Jun,r,. ' ElttiGRANT'S GUIDE. ,241 tG the tormer, from east to west, following a line of longitude, thi~ latter compound instrument would be in e~ect a double ther~om~ter11 of two branches, with a common bulb restmg upon the somm1t of the .Aleghany 'mountains. Each branch woul? exhibit its maximum .of heat upon either the coast of the Atlantic ocea~, or upon the Mississippi; and the degrees of heat measured by e1t~er branch, w.ould be in proportion to the elevation or exposure. It Is only by stnctJy attending to these complicated rules that a good table can be formed of the temperature and vegetation of the United States. "~v. 'rhe sketch of a general table of the American Climate made by a society at New-York is ingenious, but to be accurate the above tules alone ought to be adopted. 2. The difference of climate between the east and west of theAleghanys, is attended also with two material cir~umstances, that I believe have hitherto been overlooked. The first Js, that southward beyond 35 or 36° N. lat., the difference . of teinperatur~ observable .in the Ohio valley ceases, and that the climate of Georg•_a an~ ,;vest Florida from the Missis~ippi to the mouth of Savannah nver, ts substantia'lJy the same: And farthe~, that the chain of th~ A~eg?any a~d its cur:ve about the foregoing latitude, forms the real hm1t of the dif-ference. The second circumstance is, that the relativ~ excess of heat in the interior, ceases almost instantly between 43° and 45° N. lat., to ... wards the larae Canadian lakes. You have scarcely passed the southeru shore of Lake Erie, when the climate becomes cold with aston· ishing rapidity. At Detroit the tcm~eratur~ is si~ilar to that of its parallel Niagara; but at Lake St. Cla1r, the mha~ttants find the frosts much Ionaer and more severe, than at Detroit. 'I he latter small Jake b * The above observations a11e substantially cor1·ect, and, in tea!ity, co~trun the entire philosophy of this subject; but they ~lso atf'ord another smgulnr mstanc~ how far our author sacrificed his own experience to syste_m. . . . · Adopting his own ingenious thermometer, ami .app!ymg It m the ~olutlon of the problem we are investigating, the resu_lt must mev1~bly prove ?irectly ~b .. reverse of his hypothesis. Suppose the mstmment Imd upon the 38th deg1 ee north latituue, and 3 degrees west longitu~e fro~ yva~hington city, tbe bulb would rest n short uistance from Staunton m Virgm1a, the west branch would travet'se nearly the centre of the Ohio valley. . Four general cases detet·mine the ditruence of temperatura between any twe iiven places on our globe. 1o. Ditl'crence of latitude. ~l?. Ditfe1·ence of elevation. 3°. Exposure to particuh\r winds. . , '1°. Proximity to, .or remoteness from, large hod1esof ~att>r: It may be rema1·ked as singulat·1 that .Mr: Volney's ~hmatl~ ~bez·mometer woulJ nec:e ~sat·i ly exhibit, in opposition to h1s own prevwus opmwn, that tbe, valley of Ohio was . · . 1°. Equal in l11titude to a very extens1ve range of the At.lantJ~ coast. 2°. Elevated above that coast; the bottom of the Ohto &300, and the apes ef the hills 1200 feet above that coast. 3°. Exposed to the nol't.hca!il, nor~h, ~orthwest, and west winds, and covered by mouutains more lhan. 2000 feet h1gb from the south and southeast. . . 4, Remote from the warm air of the gulf stream, or the general -equahzmg effect~; of the water of the ocean upon air. . . . The assertion may be emphatically made, that, w1tho ut r~gard1~1g thc~e prtmary principle&, rao rational idia.s can be fol'med on out·s1 o1· any cllto~tte . Sl · , |
