MtfceUnnea Curio fa. 25 



ments of the Latitudes. Quod erat demonftran- 

 dum. 



Cor oil. i.Becaufe that in every point of any 

 Rhv.m Line, the difference of Latitude is to the 

 Departure, as the Radius to the Tangent of the 

 angle that Rhumb makes makes with the Me- 

 ridian ; and thofe equal Departures are every 

 where to the differences of Longitude, as the 

 Radius to the Secant of the Latitude ; it fol- 

 lows, that the differences of Longitude are, on 

 any Rhumb, Logarithms of the fame Tangents, 

 but of a differing Species ; being proportioned 

 to one another as are the Tangents of the an- 

 gles made with the Meridian. 



Coroll, 2. Hence any Scale of Logarithm Tan- 

 gents, fas thofe of the Vulgar Tables made 

 after Brings**, form ; or thofe made to Napier's, 

 or any other form whatfoeverj is a Table of 

 the differences of Longitude, to the feveral La- 

 titudes, upon fome determinate Rhumb or o- 

 ther : And therefore, as the Tangent of the 

 angle of fuch Rhumb, to t^he Tangent of any 

 other Rhumb : So the difference of the Loga- 

 rithms of any two Tangents, to the difference 

 of Longitude, on the propofed Rhumb, inter- 

 cepted between the two Latitudes, of whole 

 half Complements you took the Logarithm 

 Tangents. 



And ftnce we have a very compleat Table 

 of Logarithm Tangent s of Br iggs\ form, publifh- 

 ed by VI 'acq, Anno 1633, in \\\% Canon A'lagtmy 

 Triangidorum Logarithmicus, computed to ten 

 Decimal places of the Logarithm, and to every 

 ten Seconds of the Quadrant (which feems to 

 be more than fufficient for the niceft Calcula- 

 tor,) I thought fit to enquire the Oblique angle, 

 with which that Rhumb Line crofles the Me- 

 ridian , 



