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Show 520 Qreries. precilely', on what circumflanccs the (char! oFthe auroras imitating them in their #327} depend; ‘n' form [M. P.] , at plcafure and fipa in our apparatus "P rately, 6 ". Should not the meteor be watched at ferent {calons of the dif. year, at different time s of the night, in dinerent weathers f, and in difl'e rent coun trie s; )articularly with re! ct]; to its llrcngth duration and frequency, its colou rs, its quartcrp of appearance, and the height above: and future ohli.r bntl. ot‘its centerand leg neut mentioned i.'ation:. be compared with 7". Mr. Canton having in a beautitul theory (Litri former hillories iietl tht manta; diurnal horizontal aberr ation of the needle to local ohlerves that the in'rg heat r ~°tlricn u'ssr diurnal variation may he alike 03,5an to heat in the north; whic h at the lame time that it alihets the needl appears to produce an e aurora. :15 he adds that thc y me northern people aurora is {aid to he rema rkably llronq when a/za'l liapi‘zns after levere cold rlzz thaw ; luould all; whether tltiumzlynntarilb from warm hunnd wind , then blowing towards the frozen parts to accumulate thtLi'icity upan tht: {urtittef 83. Would it not be ac'onhrtnaLimrof this, llt«‘ll ltl "hard {outhcrly or {outhwelt winds" be olzen oblert'edto follo w in it the came of iLLCl) pales the Englillt channel alter an aurora? begins hill in the north luntll‘v ard cannot beg , thuair to the in to move till the nort hern air hasf '1 left: a vacancy; and a, luch a luceellive propag\ ation in anoth er cale was conceived by Dix Frankl _ in to he capahl e 01 bei ng madettt the rate of 1 your; will it not he a fart her coin cide nce. if the above t‘s appenr in our thanne l within 2+ or ",0 hour s :titt r the coin- ineucerncnt-jl the aurora H ?_9:. At all eteitts, are we notprovidcd ' [1h [:aliztge in a mi re perfect vacuum is attempte the vacuum of a hrt d, it might be wellto make ‘hape 1- (The nearer th place , {o as to afiord a {hot-t tranlit and much fiyate . Ii. or oblcrvation is to ramm'ma'mmttf ml , the more important it leenithe' i ' of t '2. &C. and the rate of tire earth s tor .. her, Minds in thofe parts , as l ng madc- up of {ea I LThe Virtues of b or land, &r. ii] ' , . .tl, huing tlimiuilhetl Lemon tuppole: tl:::t (luri ng heat; eafle ru parts if the earth bein morning tun, the inclinatio g full heated bv the during the morning; after n ct‘tlit- needle is therefore {tron-Lil towards the-w ‘ ry} m of the day, it h‘tu evening it returns caflward, the Wellern parts how ptitIE mes liltionary; and in the fore lels attraction. IIiiivr more heat, and therC And this regular varia ~ tion is, fumt‘ as ntigh‘i be expected ner than in winter. - The inrgu/tlr varia "Felt?!" in heat in tlle‘eartlx; whic tion he attributes to itihft-rraneous h earth heating the 5, might produce 2:43,: ‘31:; yupp'fl‘d the aurora, whirl! to he the electricity 0 re Lented air above," " h r ur appear thiet and he adds, ly 1:1"th northern menu s, as the alteration in t oiepatts mil 5 areat thehcatof ell. ‘bec the Phil: . ll [this mutt be Tram} {. r 1759 p. 403.. owed a local circumll 1-] auc ; but .1: Mr. Wtyi 1t, lays, that the know n who ohlerves ledge of it has cnabl .. him to make use ot‘ 'ould It not he well to :ihfe nt'J led r-vef ill" 331°) arrhcr (after t'onlirminn lite v, wtmesfia correltonoen rerun-Li if there is not ce heLWeeu the quai terot the hrmhtet :‘uro . 54;" It the futceetl ra', anti lne ggale, it any litth take s place ," as all}; nut/yeti] th: , _. thel'hifoi: ESSEX}; 111:1 V MICE the (I'm: 01 the nxxrruu.' befor e its commencement. 3" . n4: P- :28. L.) Farrow" Hint: by Dr. Frankl in. with one caufe of the auro knowledge, 521 prefcnt im'rcrfefi f the CVCl‘ttvIOl" tilt: , atmofphere; are our conjcftures to be expe cted exact in all their minutiae; and is not ever y thing to be received w ith candour, that ' is Pmpol‘ed with dillidence , particularly but to {L where nothing is all‘umed, CB; materials? It is however time to finil h theft: queries and comm ents; which I dowith the lineereft apology. It is leldom that Ihave been to follow Dr. Franklin with able any thing lnut admiration, hut his own modell: invitation to gucfll‘rs has here temptd in ‘ into ln‘p rudence. And to {ay the truth, as his eonjtflures were novel and ineo uztiete, I withed to prevent or moderate objections from tho ‘, who vene and love him {omenhat lefs rate thanl do; and who may not perhaps have adverted to the views and circuntl'tances of their publication. E.] "' [The following paragraph {lands in the original manufcri pt with a tingle line drawn through it. As I conceive no other reafo n {or this, than its being merely a general meteorological remark, that arifcs out of the fundamen tal principle of this lyllem of the auroras, but relates not to the aurora itlelf; I have here i a note rel‘tored it. to be in time carried to its proper place. § 2r). ‘ ll‘it ' be true that the clouds which go to the polar regions, and carry thither the vapors of the equatorial and temperate regions, [have their] vapors condenfed by the extr eme cold ofthe polar regions, and fall in {now or hail ; the wind swhieh come from thole regions ought to be generally dry, unlcf s they gain loine humidity by {weeping the ocean in their way. Andi fl miliake not, the winds between the north eru't and the north well, are for the molt part dry, when they have continued {or [onto time.' Perhaps this may he a fit place to introd uce another remark by Dr. Franklin, which hasjult occurred to my notice. Mr. Winn (in the letter quoted above p. 520, and which was addrell'ed to Dr. Franklin) had Hated that fince he had firlt made the obfervauort concerning fouth or Youth welt winds fuccee ding an aurora, hehad found it invariably obtaining in twenty -three iultances rand he adds in a farther note, dated jan. 22, 1773, a froth continuing inltance. Dr. Franklin then makes the following C01]je&ul':l-~ ‘ [form/2'5, though vilihle almoll every night olielea ‘ The Jim-nu r weather in the ‘ more northern regions and very high in the atnioi‘ phere ; can leatce ‘ be vilE'ole in England, but when the atntoi‘phere is pretty clear of ‘ Clouds tor thewhole {pace between us and theft: regions; and there- ‘ fore are feldom‘vifible here-This exteulive clearne ls may have ‘ been produced by a long continuance of northerly winds. . When ‘ the winds have long continued in one quarter, the return 15.0lt6n X x x ‘ Violent. mum» Illltllllllllll lll' 1-.- rat-u- as" |
