Iff •i «iore fq&thwly, the fouth. end will Ijjfg | T h e „ / b i l lin g B y the dip, we mean -the anglewhich the magnet makes
1 "table fßo;wsxneLdip at th e !p^c es\n acim e§ \n^e:nQ.fed. - with the Hmizon. 4, ?'|
| ; ' Laiitiide N . ■ Longitude E.-_ -Nerth Ei
53"- * ' 9 3 "•C W ’’. .. 1
L 49-
•• J itfig t
n { p H
tu d eW . •
- r?* F
* I 7;|6. j
8 4%.. s ' l i S lW '
10 T? . , 7 1 "
j . '3Sv- n . i 1 ; 7°^ 30. >
' 34; ’ h K 66., 12 j
- 2a*. . iS • HI g jjQ H |j ^ W I [Ä M iis
L -£4 . 1 1 , n | j ;Q.: 'P *
) . .»■ {*0.’ , 47 - ]9 - I f l p l 1 - 5 6 ; . ; W m -
I J 5 - gjjXHggi %:• £ $ r 5‘ t. i 0
12. 1 ;w 35 .-48.. i 26 1
! ' 10.’ "22. B s a ü 4 4 . ; 12
u . -"3
I n t y V -K -3 7- j
' -Latitude ; S. .v.
! i :. ‘e.- -W '1' | ' » P ‘‘ S 1 1
■ . 4 - . 4ö : - 3°- 3 4 ' ' . - 2 2 ; ■ ?!w m
; 7. - 3 ■ 33- | 21' , M B 1
: m 25 . ; 24 .
a M M B - r
South End Dim.
- Longitude E . \
■X- 16. 45 20&-. l a M l i 28 j ,
• ' *9 ' 28 1 2R4i- I I 4 1 . . ' ° 1 -
■ 21.. 8 ‘ i * 5- ; O S i r ’ i i w i
■ - r 3-J..: 55- *' •• ■ iS x ■f ' JZO ■ 45- 317 ' 9 47Y4
-- '4-r- : i , i:- •J74- 1
% ' i 49 ;j { j : ; i 7>7 - :
M Ä H 47 . - i 70. H m a Ä !;>
r 260. I-ttthe fame place; .the dip is fubjedfc to a varia-
; toon j it is .now about 720 at London, and from,'theiiioft
, Scutate„-obfervatipns ,on « the dipping needle belonging *
the Royal Society, i t appears to diminifli:abbut 15'
in 4 years. ~.r In'going from'north to fouth, the dip does {
not alter regularly. A f r it is extremely difficult to^ba- i
lance the needle accurafeely,, the «pedes o f the?needle are
-generally reverfed by a magnet, fo .that its two; ends? may
• -dip, alternately, and; the mean q f f beTwo idipaJs itaken. 1
1 (2011/ A b^r p f iron whichftdodsjfpr fo p e Timeiin a I
- pofition, will acquire a. degree o f magnetifm ;
^ftom^hich,, and* the*pE'asnomeqa -'ofj.the^ compafs and
dippingpeedJo there can be • no doubt 'hut 'that the;caufe |
ex ids ;in.the -earth* | Dr. H a l l e y fujpppfed'. that; the
earth- Eas -within it a largemagpetic globe: (not fixed jg
within to the external rparts-^tihaving . four;magnetic
. poles, two fixed; and two moveable^ whiefi wdh account
?Q* phenomena. - TEju-iyoyid m^te the variation |
fqhj^cb , to acqnftan t Jaw; 'whereas weiffiid; o a fe l
. changes' which cannot-be. accounted fpriupPn 4th\8 hy-
potjiefis; - This- the Dodter fuppofes may* arife ^roin^an
,hnequal and irregular diftribytion o f th e . magnetic mat-
,'ter. The^difoibution alf©'qfrtlie;feiyuginbus matter in '
the.^jell, may cauffe fbme irregularities. T h e Aurora
fiprealis has been obferved to have an effedTuppri the
needle ; and i f 1 is remarkable 3<^fftiififtahce', th a f the
'"Magnetic Meridian is'direfted'to the ceht¥q;oiThe aurorar
borealis-. ‘ RTiv in' !i^ ff^ A ^ iiolog}(kiij ObJif'VQ»
tions and_ EJaysJ ffdlldwlEg' rcdhÖimöna
from^his obferyations. T fty 'W h e f fth e W«/öWappears
to ; -n|e*orily■ about 5*, above the Horizon,
-the difturbahee of-needle is verydittfe,;and often^infäi-
flble.- 2d,_ When J t fifes qp to .the- ' 2»^thi&kn;d paffes
Iß».there.never''faiktq be a' considerable diffurbance. 3d,
'This-diftur{»^ce:conß'fts-in/ah irregular ofcillation o f the■ -
hpnz^ntalmi^dle, fo the eastward and weft ward o f th e
-mean daxlyypplition.;^an d ;;i^thi8^piace ( K e n d a lthe
excuriions on eagh fidelare^jybout, half a degree. 4th,'
When the aurora chafes, or^foon.after, the needle returns
to its former ff ation. | I t appears from hence, that there
i is fomeyhing,magne-tic in the higher parts o f the atmo-
;fpher§.
262. Mr. D al to n has..^Ifo given u&the following
.obfervations refpedtiqg Jffic efFe&ö-which^^e aurora bo-
realis-hw on the .weatller. ^Since the foring o f 1787,
There have been 2 obferved at Kendal and fCefnvich
i 8$ o f the next -fucceedin'g days -were W*/, arid
t Wm f air> a t I f&wclali now. in the account o f rain, the
||I|§I§ yearly numberof days is, 2 1 7, and o f pair days
148 y hence; thrijhancCT'of any oire “day, taken afrandom,
■ 3d, TEwar|8 the Qariobee, Pjlands, the aforefkid northeaff
'dbm^Eci-ng weLm fair, are as thofe-pVAbeKs.- 'But it
appears th^ fIq l )p|qp^rtiop^6f/Ei^daysMo w6/*'onefrf&c-
ceeding pae^/M/?o,njr,' is^- inuelv£greater than .this general
ratio o f d a y s It®-<iuet on'es ) the inference thefefore is,'
that the5#peara|eMwthe aurj&U |:|0||||is- a- WrognoffL^
cat?i©'n o f w e a t h e r . A ^
263. ^tTr^iaypeih^ps^b@|hei^®^ed5f 'that as' th(S
a 7^rbr«vGaavprlly be feen in a clear atmofphere, this cir-
.a^ffanl^l'ald^^wqEMTenJcfeMm^p^babiellha^^lpi pMpi''
.day wouldpevf^?p|But1 dpdn examining tn^qHfefyations^
it>^ppe arst>r.fh;e'aurora iidtt6nly:favours the next day;"’
but it alfo' indicates^tlia<t:a‘ feries o f days ‘to the -number'
^ 1 ^ are lildely ^®^ fair.i
^_0f 2 ^T^oje^atiom, 135 1 or 'more,
I 2 , 4 h ! 5&jk§ii 1 A ] y I y
I 2', J T - |
■ B'Uft-^'cqordmgTd^theJaws o f chanee’j the. feries ought
to have >
n ,? ’s$2_1, .'38 ;■ 2‘ ; 1 1
From'which it appears, that there, fliould not, have
beei^abdve|| aurora o"ut:©f 2 2 7 followed by.;6yi3!ir days,;
andyet,::in|fa4f,||t|ui.ere- ftp. . T he aurora is -mo-re'!
I frequently fp lp^ed by ƒ«/> weather in fummer than,in_
winter^ ^
d n ' Wlr ids.
- 264. Wind’ is<a’cuiirent p f air, arid its^ dire6tion is d e -'
nominated from that'ppm t ©rpne copapaisj^-ovz which it
comes. The .principal, i f apt,/the only caufe o f vnh(fs^'
partial, r^eJa^on^of tBe alrf b y heat.' JWn’en (t-hje
air is heated, it becomes.'raref, arid therefore afeends ; arid
the fu^rqunding cql^ air ruftiing in to fupply its plapj,'
forms V,current in fome. one dfre&ion. Wind^nfayJd e|
divided into cotiftant, pii tho^^vv^iich1.blow ^always in they
Tapie diredLion ; periodical, oi\ thofe which b ld^Half ^
year in oneJ'drrd6tion,--affd(ha lf ,a War*, in ‘a^cdnt^’fy di-
re'£tio'n'; thefe .ar-e ^callecf mon/bons j and hdniable, which.
are fubjedt to.iTO^rules. T he twps&'^OTare alfp called
trade' ‘winch. _ W e fpalj here^ give* ther;pr|ncmalJbh£^o- „
mcna o f the winds,fiomf Dr. H a l i ,^sKs accojunt thereof
in t^PplL Tranf. .
- : IH in the Atlantic and ’P d c^ O m t^ h m tt the eqiia- '
tor there -is a conftant eaft wind:
' 2d, Xfc'abofe^p^v oi^.e^hc;fflelbf^ih^Jequafo,r^tnd i
winfdph'.lhE Td.e/Mecl|pe4 ! towards tht north,edft, \
and the more fo, the, further you recede"ff-Qin tlie^cqua- '
tqr;; aridph Jouih fide it declines Hn'lihd' manner'to-'*
Wtii'ds the eafti The limits oQtffefe winds ate'great-
er in the Atlantit Ocean^p^^^^fneriGcn, than on the
African naei( |e|ttefrahig in the fprrner cafe to' about 3 2°,‘.
arid fn the latter to jabc^utf ^$3°. A n d this is |a*ue liEewife*
to the^’ fouth ward o f the eqmnbdtial'; fordedr 'bhe-jC'i^
o f cGrpo'd IPofie, the l im i t^ » h ‘e trade winds ar^3° or’^0,;.'
nearer *hn^was|4piihe' ' ■ p i
-T^injf b'efcjcmie# mpTe je^fterfy^ fd as fometimes to be',
| eaft)laid,^Orhetiriids’ 'eaft by^fpmhf;, blit moft ndtthXvards
of ' tne jeaft/'i|p|i||('|fqT%ira.« '
• Vfthv |On the c'oaff o f from!: the Canaries to
about ib 0 'N. 'latitude, thh Jwind fets in', towards the'
pnpr^f^bj;» TKeti- il>,]ie<f6uieiiJduth?weft, approaching
;'0 q£^,f;as'; yoh approach tnel5 Gape. ' But
a way-from tnelioOTis./ th'^ winds 'arepe^pethaljy betweert
, thd fouth and'TheNq^Jitjf-on -the fide they are-
^ffirhfomth'erly ;t on the more eafterly, fo as:
; tb^behbme'alm,oftl ddg eaft^T'tJ|&^he coaft o f G'uinea,
they are -fubject to frequent1 calms, 'and'"violent: fudden|
g%ft^f(|^ed^^h^pr,>-n,8m ah' points tHe' Wdrrlgaf?. .
5th; In'the' fridian 'Cfcean, the winds are‘partly con-
Jlant, ■ and partly ‘periodical. Between ’ Maclagafear ‘ and:'
Nenu-Kottandp from 1 o^To’^dMafitude^ithe wind;\o|©wS'‘
. fouth eaft i>y£eif|.;During the*,lmonths' o f 'Mayjffune>:
July, > 'Augujl, Septeihtier, ^|Iaf6refafd fouth-eaft
wMds^x^^Tcjj‘withiiif^1, oflf^e 'eq fia fo r th en fob the
other fix months, the contiaiyyntids fet in, and blow
from 30 to\i©°^S. ’ latitude, f) Trom 30 fouth' la$thKe:J
. over the Arabian; and Indian'feas and d3 ‘ay, of \ Bengal^
I from Sumatra to' thd^a^^o'f;/,'-^r/^," there is another^
mOnfoon, blowing from' OBob'er'io April on the north-eaffc
1 point, and in 'th e , other 3half’ year ‘-Kam the oppofite '
' diredlion. . Between Maclagafear and^ Africa, a fouth
i 4 fo iath^weM'y^iii'd^bldw^' rfhm? OApbefc^ which, as
till i t “
' faMs in with th4er-wefi;-fouth-'\veft winds ; 4but the Doi^or “
'. c©Mdl,hm|!dH^i^!%-f^§^|^o|^accdunt, how the winds
' ard in £he clherdialf year. f T o the eaftward'of Sumatra
and on the north fide of the e'quator a lp fe the ‘
\ coaft'\©’f -Gdmho'dia\ an'&\*C'(3ina, the1 ’monfoons. blow,|and',
r change at the fame time as before*mentioned ; buSxheir
’ diredhions are more noi therly andffoutherly. Thefe vraidpi
: reach to the Philippine Jpldhcli Japan, "B.e^eerf f
the fame hjnhrid/an^,fd^^®5 fouth fide o f the equator,”
: from Suniatra to, JiSdinepy'the fame monfb<Ms'
obferved. • T he ,ffiiMhg^hfxhefei*wind& is attemhJd' ^vith-4
great hurricanes. .
; • 265. The eail wdiid’^about t^<e;qhat6r is thus- ex—
plaiEi|dt:c The fun movihg,'j^qn^^® to weft, the‘pbihtv
• o f ^ S e a t o f the fun, 1
muft-mbye in the Tame dhpcHion1»; Wdthe' pb'int lo f g rea ts '
| gif r^refad%fe'follo'wirig the f t r f th e aihniuft‘cqEtihuai -. 1
front-tire eaft; ail'd make a confen^eaft wind. r
| 266 ,T he conftant north-eaft wind onlhc'northfi'de o ff
1 thl&%a|o r ^.an d fouth-eaft wih(hon |h'^|oum|Jdej P9?3\ ^ '
thu’slaedountedffdtf fPqeiaiT'td^.aMs the poles being den-
fer than-that at'thq’^d atbi^'^lf 'GOB^ihiinDy ruih .Lov/ards«
thd equator-; ?bifi:'as the velocity o f dffferent'parts be the
earth’s fut^.06-; from ■ it^y fot«$idn^ inca^eafes- as you ap-
pifoaeh' the equacor^i^the air which is ruthing frdha t|^r-';
north towards the equator willl>n6It^COT||nue! upon the
!fi& e meiidian, but it wiH' be^fdft behind ; that is, in re--.
St have afiirolhpii from
tha eaft,,and thefe two • motions combined1^ ptoduct
north.