A competent Knowledge of this SCIENCE, And more especially those who have, or may attend the O F SIX LECTURES and EXPERIMENTS By BENJAMIN MARTIN.< Veluti in Speculo. LONDON: Printed for W. OWEN at Homer's Head near Temple-Bar. 19 3040 THE PREFACE T HE conftant Importunity of my Subfcribers, to draw up fuch an Introduction to Philofophy, as might prepare them to understand the feveral Subjects of my Lectures and Experiments, and when these are over, to refresh their Memories, and revive, and fix in their Minds, the fleeting Ideas of what they had then heard and feen, is the Reason of the prefent Publication. I have also taken Care to oblige them in another Respect, and that is A 2 to |