uae quinque partibus orientalior
est polo mundi, respicit."

[219] PAGE 153, LINE 21. Page 153, line 26. _sequitur quod versus terram
magnam, siue continentem ... a vero polo inclinatio magnetica
fiat._--Gilbert {55} goes on to point out how, at that date, all the way up
the west European coast from Morocco to Norway, the compass is deflected
eastward, or toward the elevated land. He argued that this was a universal
law.

In _Purchas his Pilgrimes_ (Lond., 1625), in the Narrative, in vol. iii.,
of Bylot and Baffin's Voyage of 1616, there is mentioned an island between
Whale-Sound and Smith's Sound, where there had been observed a larger
variation than in any other part of the world. Purchas, in a marginal note,
comments on this as follows: "Variation of the Compass 56deg to the West,
which may make questionable D. Gilbert's rule, tom. 1., l. 2, c. 1, that
where more Earth is more attraction of the Compass happeneth by variation
towards it. Now the known Continents of Asia, &c., must be unspeakably more
than here there can be, & yet here is more variation then about Jepan,
Brasil, or Peru, &c."

Gilbert's view was in truth founded on an incomplete set of facts. At that
time, as he tells us, the variation of the compass at London was 11-1/3
degrees eastward. But he did not know of the secular change which would in
about fifty-seven years reduce that variation to zero. Still less did he
imagine that there would then begin a westward variation which in the year
1816 should reach 24deg 30', and which should then steadily diminish so
that in the year 1900 it should stand at 16deg 16' westward. For an early
discussion of the changes of the variation see vol. i. of the
_Philosophical Transactions_ (Abridged), p. 188. Still earlier is the
classical volume of Henry Gellibrand, _A Discovrse Mathematical on the
Variation of the Magneticall Needle_ (Lond., 1635). Gilbert heads chapter
iii. of book iiii. (p. 159) with the assertion _Variatio uniuscuiusque loci
constans est_, declaring that to change it would require the upheaval of a
continent. Gellibrand combats this on p. 7 of the work mentioned. He says:

"Thus hitherto (according to the Tenents of all our _Magneticall_
Philosophers) we have supposed the variations of all particular places
to continue one and the same. So that when a Seaman shall happly
returne to a place where formerly he found the same variation, he may
hence conclude he is in the same for