Page:Philosophical Transactions - Volume 053.djvu/105
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If every rhumb is then found to possess its true latitude in this chart at every degree and minute of longitude, without any sensible or explicable error (to make use of our author's own words) it follows, that the degrees of latitude are duly encreased, or that the table of meridional parts are true.
The great Doctor Halley has given us a curious method of dividing the nautical meridian, and of performing the problems in sailing according to the true chart, in Philosophical Transactions, No. 219. by a method different from Mr. Wright's, but so nearly corresponding in practice, that this alone is a sufficient testimony in favour of my author.
Our worthy brother Mr. John Robertson, in his excellent Elements of navigation, vol. II. page 358, expresses himself thus: "Now although a table thus made (Wright's table of meridional parts constructed to minutes) be abundantly sufficient for all nautical purposes, yet had the secants of smaller parts than minutes been taken, the table would have been more correct; and therefore Mr. Oughtred, Sir Jonas Moore, Doctor Wallis, Doctor Halley, and others, have been induced to find methods of constructing those tables with more accuracy than by the addition of secants to every minute.
"But a table of meridional parts, constructed by the most accurate method, only shews that Mr. Wright's tables do no where exceed the true meridional parts by half a minute, and this only near the pole; for in latitudes as far as navigation is practicable the difference is scarce sensible".—
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