AN

INTRODUCTION

то

THE THEORY AND PRACTICE

OF

PLANE AND SPHERICAL

TRIGONOMETRY,

AND

THE STEREOGRAPHIC PROJECTION OF

THE SPHERE;

INCLUDING

THE THEORY OF NAVIGATION:

COMPREHENDING

A Variety of Rules, Formulæ, &c. with their Practical Applications to the
Mensuration of Heights and Distances; to determining the Latitude by two
Altitudes of the Sun, the Longitude by the Lunar Observations, and to other
important Problems on the Sphere, and on Nautical Astronomy.

BY THOMAS KEITH.

THE SEVENTH EDITION, CORRECTED AND IMPROVED,

BY SAMUEL MAYNARD,

Author of the Key to Keith's Mensuration, and Editor of Keith's Arithmetic and Key,
Geometry, Mensuration, &c. &c.

La Trigonométrie est sans contredit une des plus utiles applications de la Géométrie
élémentaire: elle est la base de la Geodésie, de la Géographie, de l'Astronomie et de
la Navigation. - Discours sur les Progrès des Sciences, rendu par l'Institut
de France, 1809, page 6.

-

LONDON:

PRINTED FOR

LONGMAN, ORME, BROWN, GREEN, AND LONGMANS,

PATERNOSTER-ROW.

1839.