THE

ELEM E N T S

O F

EUCL I D.

VIZ.

THE FIRST SIX BOOKS,

TOGETHER WITH THE

ELEVENTH AND TWELFTH.

The Errors, by which THEON, or others, have long ago
vitiated these Books, are corrected,

And fome of EUCLID'S Demonftrations are reftored.

ALSO

THE BOOK OF

EUCLID'S DATA,

In like manner corrected.

BY

ROBERT SIMSON, M. D.

meritus Profeffor of Mathematics in the University of Glasgow.

To this SIXTH EDITION are also annexed,

LEMENTS of PLAIN and SPHERICAL TRIGONOMETRY.

EDINBURGH:

rinted for J. NOURSE, London, and J. BALFOUR, Edinburgh.
M,DCC,LXXXI.

KING,

THIS EDITION

OF THE

PRINCIPAL BOOKS

OF THE

ELEMENTS OF EUCLID,

AND OF THE

BOOK OF HIS DAT A,

IS MOST HUMBLY DEDICATED,

BY

HIS MAJESTY's

MOST DUTIFUL, AND

MOST DEVOTED

SUBJECT AND SERVANT,

ROBERT SIMSON.