L O R D A N S O N ’ S V O Y A G E
<*>ccafion, authorize muclvfeverer-ui'age) Imuft, in the next place,
• relate wherein the chart, I have here iriferted, differs from that of
-our learrred-eoantryman laft mentioned.
It is well known, that'this Gentleman was fent abroad by the
’Publick, to make fuch geographical and aftronomical obfervations,
as might faciiitaterthe future praftice of navigation, and particularly
to determine the variation of the -compafs in fuch places, as he
should- touch a t ; and, i f poffible, to afcertain its general laws and
affedtions, Thefe things Dr. Halley, to his immortal reputation and
-the honour o f our Nation, in good meafure accompliflred, efpe-
' daily with regard to the variation of the compafs ; a fubjedt, of all
-others, the moll interefting to thofe employed in the art of navi-
-gation. He likewife corredted the pofition of the coaft of Brazil,
-which had been very erroneoufly laid down by all former Hydro-
graphers; and, from a judicious eomparifon o f the obfervations-of
S others, lie happily fhcceeded in fettling the geography of many
-confiderable places, where he had, not himfelf been. So that- the
«chart he-compofed, with the variation of the needle marked thereon,
being the refult of his labours on this futgedt, was allowed by
.all Europe to be far compleater, in its geography, than any that had
till then been publiftied, -whilft it was at the fame time mod fur-
prifingly exadt in the quantity of variation affigned to the-different
parts of the globe ; a fubjefl fo very intricate and perplexing, that all
.general determinations about it had beenufually deemed impoffibfe.
But as.the-only means he had of correding the fituation of
rthofe eoafb, where he did-not touch himfelf, were the obfer-
wations -of others; when thofe obfervations were wanting, or
were inaccurate, it was no imputation on his fkill, that his de-
-cifions-' were defe&ive. And this, upon the beft eomparifon I
have been.able to make, is the -cafe with regard to that part
<of his chart, which contains the South-coal! of South-America,
"For -though-tire coaft o f Brazil, and the oppofite coaft of Peru
o n the South-Seas, are laid down, I prefume, with the greateft
-accuracy ; yet, from about the river of Plate on the Eaft-fide,
»nd its oppofite point on the Weft, the coaft gradually declines
toe
R O U N D T H E W O R L P - 97
too much to the weftward, fo as, at the Streights of Magellan, to
be as I conceive, about fifty leagues removed from its true pofition;
atleaft, this is the refult of the obfervations of ourSquadron,
which agree extremely Well with thofe of Sir John Narbo-
rough. I muft add, that Dr. Halley has, in the Philofophical Tranf-
udions, given the foundation on which he has proceeded, infixing
Port which the concurrent
journals o f our fquadron place from go'- to 71 i- This, he tells
us, wasanobfervationofan eclipfe of the moon, _ made at that
place bv Mr. Wood, then Sir John Narboroughs Lieutenant, and
which 1 faid to have happened there at eight in the evening, on
the 18th of September, 1670. But Captain m od's journal of this
whole voyage under Sir John Narborough is frnce pubhlhed, together
with this obfervation, in which he determines the longitude
of Port St. Julian to be 73 degrees from London, and the time of
the eclipfe to have been v ery' different from Dr. Halleys account.
But the numbers he has given are fo faultily printed, that nothing
can be determined from them. - . , ,
T o what I have already mentioned, with regard to the chart
hereunto annexed, I {hall only add, that to render it more eom-
pleat I have inferted therein the route o f our fquadron ; and have
delineated, in the paffage round Cape Horn, both t^e real track
which we deferibed, and the imaginary track exhibited by our
reckoning, whence the violence of the currents in that part of the
world, and the enormous deviations which they produce, will appear,
by infpedion. And, that no material article might be
omitted in this important-affair, the foundings on the coaft o f Patagonia,
and the variation of the magnetic needle, are annexed to
thofe parts of this track, where, by our obfervations, we found
them to be of the quantity there fpecified.
o C H A P .