The Errors, by which Theon, or others, have long ago

vitiated these Books, are corrected,
And some of EUCLID's Demonstrations are restored,

Emeritus Profeffor of Mathematics in the University of Glasgow.

To this FIFTH EDITION are also annexed,

ELEMENTS of PLAIN and SPHERICAL TRIGONOMETRY.

E DIN BU R G H.

Printed for J. NOURSE, London, and J. BALFOUR, Edinburgh

M.DCCLXXV.