Thesaurarium mathematicae, or, The treasury of mathematicks containing variety of usefull practices in arithmetick, geometry, trigonometry, astronomy, geography, navigation and surveying ... to which is annexed a table of 10000 logarithms, log-sines, and log-tangents / by John Taylor.

PROP. VII. Two Ports both lying in one Latitude, distant 64' or Miles, the Westermost of those Ports lieth op∣posite to an Island, more Northerly distant there∣from 47' or Miles, which Island is also distant from the Eastermost Port, 34' or Miles, I de∣mand the Course from the Westermost Port to that Island?

In the Triangle ADE, let A be the Westermost Port, and E, the Eastermost Port, distant Asun∣der 64'; and let D be the Island, distant from A 47', and from E 34': Then is the Angle at* 1.1 A required, which is the Course or Rumb, from the Westermost Port, unto the Island: To find which, say,

As Log. cr. AE 64',

To Log. Z. cr^s. AD, and ED 81'.

So is Log. X. cr^s. AD, and ED 13',

To Log. os a certain line AO 16 454/〈…〉〈…〉.

Which added to AE 64, is 80 454/1000,

The ½ whereof is AB, 40 227/1000

Then again say,

As Log. cr. AD 47',

To Radius or S. 90°.

So is Log. AB 40 227/1000,

To Sc. V. at A, 58° 51', that is N. E. by E. 2° 36' Easterly, which is the Course from the Westermost Port A, unto the Island D.

Notes

• * 1.1

  Fig. 49'.