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.

The Demonstration of this Sphere upon the Globe, is according to my former.

Here place the seventh Figure.

	d.	m.
N L,	36	54
S N, the residuum Sine	08	38	083029
L S, the residuum Sine	44	50	015178
The Sum of the Sides	90	14
The half Sum of the Sides	45	07
The Sine of the first Difference	36	37	977558
The Sine of the second Difference	00	17	769417
The Sum			1845182
The Sine of the half Sum	09	41	922591

Which 9 d. 41 m. being doubled, you have 19 d. 22 m. for the Angle at the Pole

[illustration] geometrical diagram

Fig: 7

of the Earth, then substract 6 d. from it, as in the case of Ballasore, Bourdeaux be∣ing Eastward of the Meridian of London, and you have 13 d. 22 m. for the difference of Longitude, between London and Bourde∣aux, which is 13 d. 00 m. more than the truth by Journal. See in Mr. Bonds Tables of Longitude.

And from hence you may observe, that the Magnetical Needle, or Inclinatory Needle, cannot give the Magnetical La∣titude in proportion to any one Meridian of the Earth.