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16 coordin to observations, hic I havo latet caused toto madson a littio istan in tho Shagorach, in hicli the vaporation is measum in vaporimeter os portland-cement it sursacos os belWsenis and 5 square hues, it amounts hero in 60 N. ni. o an Verage to5 da durin Jul ad August. ). Honos, ovo is, domo layto much eight upo the statemonis os ad evaporationis 13 thintho tropies, e ma nevertheles res assured that the vaporation in that orionsive and with ain il supplied regio of tho ocean, hic issWept Ver by the trade--nda, must produce a far deepe hollow, hanean e lis ti by the dilatauis of the water here occasione during the fame time by the sola heat. Whil in amount os evaporatio decreasos in hi e latitudes, that os iantali incro os Within the ice-covere rogions os in Arctic Eone the vaporation is ery early i. he precipitation os atmoaphorica molatur howevor continues o displa it activit by depressingine massos scio boneat the weight o ne layera forme upo them, and by tho co-bloch delache homine glacior . ut of tho tW Endsos motion, hich, ases have hoWn bove, ainsali occasion in the ocean, tho ne is xacti simila to that produce by Vaporation, o that ra-Di in lyher latitudes has the fame secet o the oceani' movement 8 evaporation in lower. vaporation in ac disturba the quilibrium omnio in bottom, and thus cauae throughout the hole area os tho sectiona afflux to the vaporatin region Minsali, a longos the sal continues also disturba the equilibrium at the a doWn to th bottom, and causos an ossiux hom tho region, here it salis. he oster effect produco by iantali, consist in a perturbation os tho quilibrium os tho superficia strata, hicli continues long aster in res has coaso to sali, whereby unles the motion e reVented by the causes, a sursace-stream os more durable character must e produced soliowed by an in-war floWiti current beneat it. Alroah in dissereno os levet et eo tho equatoria an potartracts of the ocean, hicli a caused by Vaporation, a much greater than the opposito difforeno caused by eat B in offoc os alasali, which may bo considero a a complement to vaporation, his lΘVel-
thos observations, hic have originate in the interest ahen in thoquestion by the Goteborg Hushalining Societ and the ord-Lieutonant of tho di
strici Count ERRENAvλRD, I hope ereaster, hen the have been continue somo time longer, o ive a fuller account.
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be Wo streams, ne os large section, toWarda tho equator, in other ashallo sursace-current os Warm ater, rom the equator and the formerstream, as ein caused by a more rapi change os levet, ill care to-Warda the equator far more ater in a uni os time, than the lauer illcare hom it. In addition to these two motion there illis a third, Vi a sursace-stream, oscendis to ard lows latitudes, caused by ths disturbance of the superficia strata' equilibrium, hichisa the secondconsequenc os aintail. Τhe origin os these vast troam then is to b lookod sor in disturbances of the coan' levo so mali, that thoi das amount canonj be exprosse in millimhtros and hactions os millimhtros. ut Whentheas littio changos os lovo beon to or upo sto quiescent mass, thedissereno os suo increases in a mors rapi ratio than in stream it produces, and when oth a las have reache a constant stato tho dinserenos os leve may Mily be considerabie. From in taci, that in change os leve produco by evaporationand iantali is greatei tha that resulting rom eat, e re not orcedio conclude that in se leve around tho potarcirclo is h hs inanat the equator for the descendin curroni, hic the forme in combination produce has a sar greator opth than th ascending Warm stream, and tho dissoronos os levet, hic occasiona the forme Stream, maythere ore much ooner arriVo a ita maximum than stat, hic has todrius in latior. a rogarda his question may rofer the reade towhato avo abovo more fuit uald, rogarding the motion os ursace-
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it dilatation through hoat illistready bo tolerabi rapidis a tempe=ature scio as M' Cent. and that in dilatation, though it reali in- creases at hi e temperatures, oes no increme so rapidi as a lomer. Τho solio nitituo tabis, hic indicato the increas in Volume, hich100,000 volumes os fea-Water acquir for an increas of 1 Cent of heat, an bosido hic Ι have so the sine os comparison, placed the correspondin cipher so pure ater, ill maho his vidoni ).
Wo oo hors that in dilatation os fea-Water at in temperaturos, whioli ako place in the superficia strata of the armer eas, is notiso much greator than that os pure mater, although a lom temperaturos, hicheus iners may be et it deo unde the surtace, it a b 10 times moro rapid. V oration o the ther han at lo temperaturosis mali, ut increases Ver rapidi Wit increave temperaturo. ho influouco os in se sal in indering Vaporation a mors sensibis a loWthan at igh tomperatures, although that influence of V, p. c. salicis in genera very trifling. Let u suppose in Whol ocean o me had a temperatur ossor examplo M Cent. and that he nequa distributio os in solarhoat oro just sinning to influenco the surtace. ΑΗ the vaporationo tho mater ould a suci a temperature e loW, heroas iis dilat sonoould Hrsad be tolerabi rapid the firs offect os in hoat uotchisfl to bo a sursace-current homine equator toWard the potes, solio-wod is an unde circulation in the opposite direction, as I havo homin xplaining the stream produce is eat. his under-circulation ill
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44 F. L. ΚΜΑΝ, noon increas in proportio a the einning evaporatio cauae a simila motion. he diu freno os lΘvel, hic evaporatio an subsequentraintai produces in a uni os time, ill e aster a While, in consequenceo tho incroaso tomporatur of the wator firat equat to and then greater tha that arising rom hoat an it ould Beem ascis the warm ursace- current ough in consequenco to diminia an ultimatet coaso. Without entering into the question, hether at an stage of the current' developement an suo event in place, it is clea that he in temper ture os the se Water has reache the maximum, hicli is detormin6d by tho limito accossion os heat and the constanti increme los os heat, the vaporatio an raintai Wil generali spoken e constant, and thusalso the chango os levet, hic the produco at a certain place in auuit os time, ill o a constant quantity. ut in consequence of this, tho dissereno os levet, caused by the abovo med hanges os levet mustastor a timo obtain ita maximum on hic the assiux to the vaporatingregio must ecome constant. he inhing of the sursace throuo evaporation is then alWays componsato by assiux, and the leve in the evaporating localit is thus maintaine constant. Is me no QVen SUPPOSΘ,
Would remat thore, iis salines and weight ould e more an more increased by evaporation, and oon a vertica circulation ould arius; this circulation Ouid indood bo limito bocause of the greater density, hic tho lower ater-strata avo hominet lo temperature, ut that limit ould bo continuali loworo by the inhin molocules, hichwould also car th them into the deo the waruit the had acquirodat the surtace. hus tho hichnes of tho arme stratum must alWaya increas an consequently iis leve bo aised unti it came to coincidemit that that os in surroundin Walsr. ho eate Water ould thenboin to o out ovor his ast an in heat to produce ita ursace-stroam, jus ascis no hollo ha bos forme by vaporation.
Wo mus no overtoo the circumstanos that in his case the levsi os the water-strata ave o been accordiu to the common rute, dolormine by the proportion os thei specific gravities. he armerwater beneat the speciali ovaporatis region assumes a much lomerlovet, hancit accordin tociis specific eight ought to occupy, and thus exorcissis a sar les hydrostati pressure tha the surrounditi coider ater. But just on his account this alter an o in ascis into attollo. Tormod by ovaporation. though no suo hollo bo thoro. An
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ossentia conditio sor the circulation, caused by the nite effect fovaporation an rainfall, ain the or here described, is the temporatur os tho mater in the leas vaporatin region I, Supposed . . that the warm ursace-current preserve it Onc assume temperature, instoad os coolinii the igher latitudos the whole mas os mater mustultimatot b raised to a tam temperature, in hicli caserit Aeem possibis that the molecules concentrate by evaporation tot in down, so that the circulation ent ut rom tho mos heate place into thodoop. ho assiux ould the tali placo hom the surtace, ascis the casein the editerranean, horo the ours of the stream is confine to out the fame latitudes, instea os croasin thema in the ocean. his modo os circulation in homediterranean is howeve also spociali sa-vours by the mali dimensions of the poning so tho admission ostho inflowin mater relativel to the ursace exposed O Vaporation. havs onMavoured o hom, stat in the horae par of the oceani consequence of Vaporation, ainsali an heat, there uot to e sor- modo road an dos hollo filio Min arm an salter ater statinis hollo is continuali fisso u Do bolo by two deo strem oscol Water, ne hom ach pote that the greates par of the confluent mater Vaporates etWeen the tropios, ut that another pari flows achagain ver the edges of tho ollo in tho form os a hallo broadstrisam os arm ater, and that this arm current uotis a certain latitudo to e et by anoths superficia current os old, ut les saltWater, arising homine perturbation os the superficia stratas equilibrium, whio tho ainsali in tho hio latitudos ad testis one oscit consequen
B in rotation os tho art the stream proceodin toWard thopoles receive an impulso toWard the ast, hos descending roui thopolos an impulse toWard tho est, an even in his a reason is apparent, is in ascendin Warm an descendin colostream Ahould boable to as by ach ther, ac on ira Wu id of tho charinet, instoad os comis in collision; ut hors remians an other an proba lystili more activo foros to e talion into consideration. ho road bottos armo Water e eo the tropic is attached by the trade--nd in
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46 F. L. ΕΚΜΑΝ, dono to o out to the orth and ouin is thus counterbalanced, and at tho amo timo it is continuassy rivo toWard the wost untilina motion is limite is encountoring a continent. he fisci os thesola heat pon the ea-Wister must inorosor hore bo collecto ascis to kiud os sociis, o the ovo will hero b elevate by tho dilatation, that the water has undergone incit passage ove tho hole region justmontioned, and by the trade--nda, eapin ii in Warmed ater onino coast. his ater an here flow o With so much the mors orco, a tho mo os in sal Wind in tho vicinit os continent is debilitato an bocomes irregular. Insisad os hs rotativel thin, ea andoasit chille sursace-stream, hic sis sat could have produced is ino
Siso, hic as si by thei pomer a thoi other properties have beyondother attracte universa attention; reel floatingistream os Warm daris blue ater, movin Wit considerable volocit in 'od os more dilutod, cold, and discoloured ater homotos latitudos, hic the dra tothomsolve pomersuti by mechanica reaction, and wit Whic the pre
stances relatin to the contour os the continent' easter coas,line,
hic so essentiali contributo to increas tho intonsit os in Atlantio Gul stream an to reduce tho latera effiax of the equatoria stream, bosor the current has et roache the regions, here in Gul stream properi so calle developes itssis. Neither an the great quantit ofriver-water, hicli is potared ut into in Gul os Moxico, or is carri ed thithor in tho AEquatorial stroam, dat to exorcise an influenc on the
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atrono os in Guls-stream. Evencis in acces of river-Water and thogreater amount os res in the Gul os exico ars no uincient to produce an absoluto is os the water' levet, the must at an rate operate essentiali to provent a sinhing of tho ursace throuo evaporation, and thus effectis is relativel to tho coan ulside themul O this mustbo adde also in influonco os in reaction-stream os rivera, is indeed these, as in probabio, ars sed rom the ocean itfel o aliould remember that rivor ater, hic is potire into an ocean-guis, even is it adjuat time to evaporato bosore learing the uis mus neveriheles pro
But ono of the hie causes os tho strongili os tho Atlanti GulRStream an os tho great exton toward the orth-east os the sursacedrist, hic som a continuatio oscit motion, concelus to e thelaeo communication etween in Ailanti and tho Arctic-Oceans ), and the relatio that honos arises et eo the wo Suriace-Streams, amelythe ascenditi Warm an sali, and the descendin col an diluted. oremember that his latior stream a a secondar effect os rainsul, ain-soroe by the sursaco-stream, hicli col produco by sorminiice, hichis sterWard dissolve by the wator. t ma perhaps seem ascis his descendiu stream ought is the bove inve grounds for the explanationos in ocean-stream be accepted, o oppos an insuperable obstacte totho progress of the ascenditi stream, in s much namel a the hanges os levet, that inve is to the streams, appea to operat at Very instant to stablis a hictor ea-levo in hioer than in lomer latitudes. But e must recollect that tho causes mos effectivo toWard this Dd, vig the absoluto amount os iantali an evaporation, produce a Verydes suom and thus in proportion to tho greatnes of the change os levet, a relativoly mali dissereno os levet. his differetice tot sur-ther, have bove hown, e compensate by the effect os heat, Without the sursaco-curroni, hic mas produced by heat,asing dobilitatod. Τh differsne os lovel again, hicli causes the descending sursace- current, dependa exclusiVel o the relation etween the ursace tratas specise eighis, an must heresore bo ery mali, and oes not a far
y m. CARPENTER has experience the fame opinio though pon different ounds, amet o the round os a supposed suction, occasione by the mater sin-hing in the old ola region os in ocean.
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a one an See acquire an increas hom an separat circumstances.
Τho stream, atready rom ita commonoemen diffused ver a tolsr ly de surtace, presse ituet in consequenceis,es,ard deviation to ardatho morican coas liue, by rictio against hic it musiclos a portionos iis power. As regard the ascendin stream, the differetices os levet, Whicli rivo it ars also originalty butismali, consistingis a change of the water' volume through eat. Os itsol that hange os volum Would probabi oni have produce a very hallo an seebl stream But moliave een o that troam by the ageno of tho iud has ad iis stariing oin remove to the astam coasi os America, there acquiredan increass drivinisorce in tho difforonos os levet, caused by the trad Winds, and then, after liminiboen surthor reinsorco by the effocis os other circumstances, et ut illi collecte sorcos o find iis Way throno
the ro ocean suppos that, hen ali hos circumstances are inhoninio consideration the ground here assigne a the originis the streamn Williso bo ound contra ou experienc os tho ours of these su face-currΘnis, ve though e cannot inve a numerical proos os thois
Τ resumo no the threa os ur explanation, hic has sensor a momen brohen RQ must remin tho reador os,hates statodsomo time bach that ver ocean-current mus have iis coura in me inin moMure dependent on the possibilities, that ars prssente os iis combining illi ther ocean-currenis. Both the ascendin Wam sursace-
col sursace-current must ovohe reaction-streams, with hicli tho armascenditi stream an combine, an in hisci se a separate cause, hy
an iis marhed character a a stream, noveriheles continues as a risistream to xten itfel past tho coasis os Scandinari u evon to Spitκ-borgon an into the static Ιc Ocean. heiul stroam must in turn bring bout a reaction-stream in the opposito direction, illi hic thocol descending ursace-stream an partiali unite. Whs have thus, in addition tho inbovo adduco principat cause sor a descendiu cold
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under-current in the Atlantio, notho though os subordinato importanos an more loca operation, vig the Gul stream' mechanica reaction. Τhis combination os tho troam With ach thor is facilitato by causo, hicli a been by omo asserte to e the ni caus os the
Bursaee-stream' conversio into unde streams, Vix the relations os tem
lose irasis incit is it hould bo connected it an vertica circulationos great extent, tarin placo Mihin tho ola tracta, W mayin a causesor his in in concentration os the wats by tho sormation Osric a thotimes an places, hen and Whoro that procos inhes place. ut urhnoWledg os the wator' motion in thes rogion is in ac to limited,
t Warrant an genera conclusion relativo i iis causes. The specia object of this or has no been to explain certain Particular Ocean-streams, ut ather o sok ut in causes, in hichocea current in genera originato. ut an important ouchstone sorthe correcines of a thoor is tho triat, hether the phoenomena, actuallypresente by nature, an by it be explesne in a cloar an satisfacto manner. t Was herosore speciali With respect to reaction-stream de- strabis to endeavou to apply the theor to ome particular case, heroth circumstances, hic ma inve is to suo streams seem toto present in abundanco. ho xplanation os the current in tho Scandinarianwator an in tho Striat os Gibraltar ould thus o a secondar resultconsequent to the provin os the theo 's applicabiliW. For the samereason it appeare to moraestrabis to inquiro, at hat conclusions With
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50 F. L. ΕΚΜΑΝ, respecto the ourΗ os the ocean-currenis, e aliould arrive is, eudoavoured to form an ids of What motion thos causes os currenis, Whioli in in sartior pari os this essu We have reare separalely, Would produce in the Deo ocean. t hero appeared that ni in the case, henW talis into account ali the above Damed causos theae motions seemed tocorrespondisit inose, presente by realit in a porsec segmon os tho Ocean, . . the Atlantic etWeo the equator and the orth-polo. sno these forcos ars eridenti os such a nature, that in a complete segmentos tho coan tho must ali come into operation this circumstanc appears to me in eo proos os the correcines of tho vioW ahen. have also talion in opportunit to poliat ut tho sod os thoroughi investigatingcertain data, hic have hitherio boon muc neglected a bein necessar so tho quantitativo determination os tho cause of the streama,
Which hould bo no os tho principia problom os hydrography. I placeamon thos in tho firs placo in amount os evaporation and WhereVerit an e carris out the determination os hs msan ater-lovel in disserent portion os the ocean. Is, talio a gonora vis of tho effecta, producedipo the ocean
dissereno viz: a sursace-stream, causod by a limii ed, and a deep-stream by an unlimite disturbano os tho quilibrium. Hem produces a Suriace-Ηtream by Warmin tho ater an a deop-stream by Vapor tiniit. Cold an produce an unde current by the contractio an stillanore by the concentration of tho ator, ut it the leaves a the sur- face a tendenc to disturbano os quilibrium, hich shows itast in thesor of a si face-stream noli mellin os the ice Rainfali causes deepistream a it immediate consequenc an a sursace-current stighter ater a a scondar effeci. Miud occaΗion directi su ace- currenis, an deep-stream by chaning tho levol. Rivm 3, an similarconstant ut-po ings of ighter Wator, ove immediatet rise es to Sursaee-Streams, ut produc under-currents by mechanica reaction; stream os his alter in osten accompan even ine bove mentioned. The pocific gravit os hs Walor plays in ali these cases a Ver varied, but in ome or ther respect alWays important pari. It usuali dete minos the leve os tho ater-strata, ut uot alWays. Α to the origine independendi os tho variations is specific 'eight arm especialin tho