Page:Cyclopaedia, Chambers - Volume 2.djvu/936

 V A R

t V9 ]

V AR

of Magellan, it decreafes i, Degree.,, and at the Weft En- •«„;„ be „ eateft> and from thence decreafe

lnnlw ;„ iUO. C.J .1 -~ ~ __ B.

trance about 14 Degrees. 4th, That Eaftward of Srafil,

this Eafterly Variation dcreafes, fo as to be very little at St. Helena and Afcenfion, and to be quite gone, and the Compafs point true about iS Degrees of Longitude Weft from the Cape of Good Hope. 5 th, That to the Eaft- ward of the aforefaid Places, a Weftward Variation begins, and governs in all the Indian Sea, arifing to 18 Degrees un- der the Equator, about the Meridian of the Northern Part of Madagafcar ; and 27 Degrees and

Accord- ingly, tn faft, we find that at Sreft the Variation is but 1 j gre y Qif arters i at London, 4 Degrees and an half; and at JDenizick 7 Degrees, Weft. Again, to the Weft- ward of the Meridian of the Land's-End, the Needle ought to have an Eafterly Variation ; were it not that (by ap- proaching the American Northern Pole, which lies on the Weft fide of the Meridian, and feems to be of greater force than this other) the Needle is drawn thereby Weftward,

half in j, Degrees fo as to counter- balance the Direftion given by the Euro

South Latitude, near the fame Meridian : Eafterly from pean Pole, and to make a fmall

Weft Variation in the Me-

ridian of the Lands-End it felf. Yet, about the Ifle Ter- cera, tis fuppofed our neareft Pole may fo far prevail as to' give the Needle a little Turn to the Eaft; tho but for a very little Space ; the Counter-balance of thofe two Poles permitting no confiderable Variation in all the Eaftern Part

thence, the Weft Variation decreafes, fo as to be not' much above 8 Degrees at Cape Comorin, and about 3 Degrees upon the Coaft of Java ; and about the Molucca Iflands to be quite gone ; as alfo a little to the Weftward of Van Tiiemens Land. ffth, That to the Eaftward of the Mo- lucca's and Van piemen's Land, in South Latitude, there of the Atkntick Ocean V not "upon the Weft "60Xrf.Es- ar.fes another Eafterly Variation, which feems not fo great land and Ireland, France, Spain, and SaXw- BuT to as the former, nor of fo large Extent ; for that at the Ifland the Weftward of the Wm, the Power oi H Amerieal Rotterdam, it is fenfibly lefs than upon the Eaft Coaft of Pole, overcoming that of the European, he : Need e has m Guinea ; and at the Rate it decreafes, it may well be chiefly refpea thereto ; and turns ftill more and more .0-

wards it, as_you approach it. Whence it comes to pafs,

fuppofed, that about 20 Degrees further Eaftward, or 225 Degrees Eaft Longitude from London, in the Latitude of

20 Degrees South, a Wefterly Variation begins. 7th,

That the Variation taken at Saldivia, and at the Weft Entrance of the Streights of Magellan, fhews, That the Eaft Variation noted in the third Obfervation, is decreaf- ing apace ; and that it cannot well extend many Degrees into the South Sea, from the Coaft of 'Peru and Chili, leaving room for a fmall Wefterly Variation in that Traft of the unknown World that lies in the mid-way between

that on the Coaft of Virginia, New England, Newfoundland, and in Hudfon's Streights, the Variation is Weftward ; that is, increafes as you go from thence towards Europe : and that it is lefs in Virginia and New England, than in New- foundland and Hudfon's Streights.

2, This Wefterly Variation, again, decreafes, as you pafs over the North America, and about the Meridian of the middle of California, the Needle again points due North ; and from thence Wellwards to Tedzo and Japan,

Chli^i New Zealand, and between Hounds Ifland and 'tis fuppofed the Variation is Eafterly 5 and half Sea orer

f V"TT~/r 'r f ? North-weft from St. He- not ie!s than 15 Degrees: And that this Eaft Variation

lena, by Afcenfion, as tar as the Equator, the Variation extends over Japan, Tedzo, Eaft fartary, and part of Chi-

continues ; very fmall Eaft and as it were, conftantly the na, till it meet with the Wefterly, which is govern'd by

fame : So that in this Part of the World, the Courfe, the European North Pole, and which is the greateft ; fome

i, in there is no Variation, is evidently no Meridian, where '-

but rather North-weft. — -9th, That the Entrance of Hud- fin's Streigl-t, and the Mouth of R. Plata, being nearly under th' 2 Meridian, at the one Place the Needle va-

ries 29 Degrees and a half Weft; at the other 20 Degrees and a half Eaft. a

theory of the Variation of the Needle. From the Circumftances above rehearfed, the learned Au

n Rufjia. 3°, Towards the South Pole the EfteS is much the fame; only that here the South Point of the Needle is attraaed. Whence it will follow, That the Variation on the Coaft of Srafil, at the River of 'Plata, and fo on to the Streights of Magellan, fhould be Eafterly ; if we fuppofe a Magne- tical Pole fituated about 20 Degrees more Wefterly than the Streights of Magellan. And this Eafterly Variation doth extend Eaftward over the greateft Part of the Ethiopick

thor takes occafion to affert, ' That the whole Globe of Sea, ; till it be counterpoiz'd by the Virtue of the other

the Larth is one great Magnet, having four Magnetical Southern Pole ; as it is about mid-way, between the Cape

Poles, or Points of Attraaion ; near each Pole of the E- of Good Hope, and the Hies of fri ■ftan d'Acunha.

« quator, two; and that in thofe Parts of the World which 4°, From thence Eaftwards, the Afian South Pole be-

lie near adjacent to a™ one of thefe Magnetical Poles, coming prevalent, and the South Point of the Needle being

the Needle is govern d tnereby ; the neareft Pole being attraaed thereby, there arifes a Weft Variation, very great

always predominant over rhe more remote.' in Quantity and Extent ; becaufe of the great Diftance of

1 he Pole whichat prelent is neareft to us, he conjeaures this Magnetical Pole of the World. Hence it is, That all

the Indian Sea, as far as Hollandia Nova, and farther,

to lie in or near the Meridian of the Lands-End of Eng land, and not above 7 Degrees from the ArBick Pole : by this Pole, the Variation in all Europe and T'arta.ry, and the North Sea, are principally govern'd ; tho ftill with fome regard to the other Northern Pole, whofe Situation is in the Meridian, paffing about the Middle of California, and about 15 Degrees from the North Pole of the World; to which the Needle has chiefly refpea in all rhe North Ame- rica, and in the two Oceans on either fide thereof, from the Azores Weftwards, to Japan, and farther. The two Southern Pole

there is conftantly a Weft Variation ; and that under the Equator it felf, it arifes to no lefs than 18 Degrees, where 'tis moft. Add, that about the Meridian of the Ifland of Celebes, being likewife that of this Pole, this Wefterly Va- riation ceafes, and an Eafterly begins, which reaches to the middle of the South Sea, between the middle of Zelandia Nova and Chili ; leaving room for a fmall Weft Variation, govern'd by the American South Pole.

5°, From the whole it appears, That the Direaion of the , he imagines, are rather farther Needle in the Temperate and Frigid Zone, depends chiefly diftant from the South Pole of the World : The one about upon the Counterpoife of the Forces of two Magnetical 16 Degrees therefrom, in a Meridian fome 20 Degrees to Poles of the fame Nature : As aifo why, under the lime the Weftward of Magellan Streights, or 95 Degrees Weft Meridian, the Variation fliould be in one Place 29 Degrees from London : This commands the Needle in all South A- and a half Weft, and in another 20 Degrees and a half Eaft. merica, in the Pacifick Sea, and the greateft Part of the 6°, In the Torrid Zone, and particularly under the Equi-

Ethiopick Ocean. The other feems to have the greateft noffial, refpea muft be had to all four Poles, and their

Power, and largeft Dominions of all, as it is the moft remote Pofitions well confider'd; otherwife it will not be eafy to from the Pole of the World, being little lefs than 20 Deg. determine what Variations fhall be ; the neareft Pole being diftant thercrrom, in the Meridian which pafles thro' New always ftrongeft : yet not fo, as not to be countcr-balanc'd Holland and the Ifland Celebes, about 120 Degtees Eaft fomctimes by the united Forces of two more remote : Thus, from London : This Pole is predominant in the South Part in failing from St. Helena by the Ifle of Afcenfion, to the of Africa, in Arabia and the Red Sea, in Perfia, India, Equator, on the North-weft Courfe, the Variation is very

1 in that whole Traa unalterable ; becaufe.

and its Iflands ; and all over the Indian Sea, from the Cape little Eafterly, and it

of Good Hope Eaftwards, to the middle of the great South the South American Pole (which is confiderably the neareft

in the aforefaid Places) requiring a grear Eafterly Varia-

Sea that divides Afia from America.

Such feems to be the prefent Difpofition of the Magneti- cal Virtue, throughout the whole Globe of the Earth. It remains to ftiew, how this Hypothefis accounts for all the Variations that have been obferv'd of late ; and how it an- fwers to the feveral Remarks drawn from the Table.

tion, is counterpoiz'd by the contrary Arrraaion of the North American, and the Afian South Pole ; each whereof, fingly, are, in thefe Parts, weaker than the American South Pole : and upon the North-weft Courfe, the Diftance from this latter is very little varied ; and as you recede from the

. Then, it is plain, that as our European North Pole the Afian South Pole, the Balance is ftill preferv'd by accefs is in rhe Meridian of the Land's-End of England, all Pla- towards the North American Pole. In this Cafe, no notice ces more Eafterly than that,_ will have it on the Weft fide is taken of the European North Pole ; its Meridian beim

of their Meridian ; and confequently the Needle, refpeaing it with its Northern Point, will have a Wefterly Varia- tion ; which will ftill be greater as you go to the Eaft- wards, till you come to fome Meridian of Rujfia, where

little remov'd from thofe of thefe Places, and of it felf re- quiring the fame Variations we here find.

After the fame manner, may the Variations in other Places, under and near the Equator, be accounted for : So

that