Page:Philosophical Transactions - Volume 053.djvu/104
[ 70 ]
of by divers, as namely by Martin Cortese, Petrus Nonius, and even Gerardus Mercator seemeth to have corrected them, in his Universal Map of the World; yet none of them had taught any certain way how to amend such gross faults:" And, in his Preface, he declares, "that, by occasion of Mercator's map, he first thought of correcting so many and great absurdities in the common Sea Chart, but the way how this was by him done, he neither learnt of Mercator, nor of any man else."
Wright's method (erroneously called Mercator's) was at this time then adopted, has continued ever since in use, and has been improved by some of the greatest mathematicians who have flourished since that time, and although sometimes attacked, yet it has been found impregnable.
The first person (that I am aware of) who charged Mr. Wright with errors in his tables of rhumbs, is Simon Stevins, in his large volume of mathematical remembrances, which Wright himself plainly confutes in a subsequent edition of his book: now, Stevins does not condemn the principles, but only asserts that his tables have some faults in them, and endeavours to prove that the fourth rhumb at 78 deg. of longitude ought to have 61d. 26m. of latitude, whereas Wright makes it only 61d. 14m. Hence, the great difference is no more than 12 minutes; and what inconvenience can arise hereby to the mariner in such a run, was this the fact? But it turns out otherwise, for this difference is reduced to less than one minute (even according to Stevins own way) as evidently appears from Wright's answer in page 214.
If