The longitude not found, or, An answer to a treatise written by Henry Bond, Senior, shewing a way to find the longitude by the magnetical inclinatory needle wherein is proved that the longitude is not, nor cannot be found by the magnetical inclinatory needle / by Peter Blackborrow, Gent.

In Answer to Mr. Bonds first Question, in finding the Distance between London and Vaygats; and from thence to find the Di∣stance of the Magnetical Pole, from the Pole of the Earth.

LOndon Latitude 51 d. 32 m. North, London Longitude 00 d. 00 m. Vaygats Latitude 70 d. 00 m. North, Longitude 58 d. 00 m. Westwards of the Meridian of London, to find the Distance between London and Vaygats L V, and the Angle P L V, and the Angle P V L. In this Triangle we have P L, the Co-latitude of London 38 d. 28 m. and P V, the Co-latitude of Vaygats 20 d.

00 m. And the Angle L P V 58 d. 00 m. the difference of Longitude by Journal between Vaygats and London; to find L V, the Distance 31 d. 57 m. and the Angle P L V, 33 d. 14 m. and the Angle P V L 94 d. 30 m. And from the Angle L P V, Mr. Bond draws an Arch as P M V, and makes that an Angle of 8 d. 38 m & the An∣gle P, M, V, L, an Angle of 85 d. 52 m. and then Mr. Bond draws another Arch as L M, and makes the Angle P L M, an An∣gle of 11 d. 15 m. and the Angle M L V, an Angle of 21 d. 59 m.

Here place the first Figure.

If Mr. Bond would make it a proporti∣on in his Angle to draw two Arches from the Pole of the Earth, unto the Meridian, and Parallel of Vaygats; as P V, and P M V, then he should have drawn another Arch in∣to the Meridian and Parallel of London; from the Pole of the Earth, besides that of P L.

For as Mr. Bond would separate the Va∣riation of Vaygats 8 d. 38 m. from the An∣gle

[illustration] geometrical diagram

Fig. 1

P V L 94 d. 30 m. and make the An∣gle P M V, 8 d. 38 m. and the Angles P M, V, L 85 d. 52 m. by another Arch from the Pole of the Earth.

So likewise should Mr. Bond have sepa∣rated the Variation of London 11 d. 15 m. by another Arch from the Pole of the Earth into the Meridian, and Parallel of London at L, in regard the matter given requires the same Demonstration.

And whereas Mr. Bond draws two Ar∣ches from the Pole of the Earth, unto the Meridian, and Parallel of Vaygats; it is very improper, for no Arch can be drawn from the Pole of the Earth unto the Meri∣dian, and Parallel of Vaygats; but what was drawn from the Pole, as P V 20 d. 00 m. the Co-latitude of Vaygats, which Arch is the nearest Distance unto the Pole of the Earth.

And for the Arch P M V, it makes a greater Distance than the Co-latitude of Vaygats, by 00 d. 18 m. therefore Mr. Bonds Angle is a false Supposition, for one and the same Meridian and Parallel of the Earth, can have but one Arch or Meridian

from the Pole of the Earth, and that is the nearest Distance.

But Mr. Bonds pretence is to find the Distance of the Magnetical Poles, from the Pole of the Earth; and he saith, in the year 1580, the Variation was 11 d. 15 m. at London, and at Vaygats 8 d. 38. m. and the Co-latitude at London 38 d. 28 m. and the Co-latitude at Vaygats 20 d. 00 m. and the Difference of Longitude 58 d. 00 m. So from hence it may be observed, that the Distance of the Magnetical Pole, from the Pole of the Earth, is found, from the Vari∣ation that was at London, and Vaygats in the year 1580. So that the Magnetick Pole must be as various as the Variation, in regard it cannot be found without it.

Mr. Bond had better to have begg'd the Question, let the Magnetical Poles be Di∣stant 8 d. 30 m. from the Pole of the Earth: For his Angle cannot be demonstrated up∣on the Globe.

[illustration] geometrical diagram

Fig: 2.