VOL. LIII.] PHILOSOPHICAL TRANSACTIONS. . ^97 



West, of Exeter, revised by J.Rowe, in which it is strongly insisted on, that the 

 graduation of Mercator's chart is erroneous, and that the same, if rightly corre- 

 spondent with the loxodromiques or rhumbs, should be graduated as a line of 

 natural tangents, from the equinoctial to the poles. Now this error might have 

 passed the less observed, but the Critical Review of last month sets it forth as a 

 masterly performance, and a thing of the greatest merit and importance in 

 navigation. 



That there is a respect due to Edward Wright for his invention, that his prin- 

 ciples are true, that Mr. West, or his editor, and both (if both of the same opi- 

 nion) are false, is most certain. That the characters and abilities of Dr. Halley, 

 Sir Jonas Moore, Mr. William Jones, Mr. James Hodgson, Mr. Haselden, and 

 many others, for they are almost numberless, both of higher and lower mathema- 

 ticians, who have written on the certainty and utility of Wright's chart, that the 

 characters and abilities of these able geometricians are attacked by Mr. West and 

 his editor, and by the Critical Reviewers, is plain, and that this will have great 

 weight with many not over well acquainted with geometry, is no less plain. 



But there are other circumstances ; Edward Wright himself gives the very 

 same construction by his words, as Mr. West does, though his tables make out 

 quite another thing, that is, both Wright and West say expressly, the sphere 

 being in the hollow cylinder, and the equinoctial remaining fixed without swelling, 

 while the other parts swell towards the poles, the chart will be formed. But in 

 this, Wright has badly expressed his own thoughts, for his tables make it that 

 the equinoctial must either swell or contract itself. And this is very excusable in 

 Edward Wright, for at that time geometricians had no notion of fluxions, or the 

 increase of magnitude by local motion. Mr. West and his editor have therefore 

 fallen into this error ; they have taken the words, but not the sense of Edward 

 Wright, and the Critical Reviewers vindicate them, and make it as if this pro- 

 perty had been communicated to the Royal Society by Mr. West. The proposed 

 demonstration of this tangential property, at page 58 of Mr. West's book, is no 

 demonstration at all ; there is nothing more plain than that in order to have the 

 meridians at equal distances, the degrees of latitude must be enlarged to the 

 same proportion in every part, as the circular meridians are nearer towards the 

 poles, which proportion is as the cosine of the latitude to the radius. 



XIX. A Defence of Mercators Chart against the Censure of the late Mr. IVest, 

 of Exeter. By Mr. JVm. Mounlaine, F.R.S. p. Og. 



The greatest single advantage that the important business of navigation ever 

 received, was from the invention of the mariner's compass; and next to this, the 

 projection of a true nautic practical chart claims place. This last was performed 

 by that great improver of navigation Mr. Edward Wright, as appears by his 



VOL. XI. 4 U 



