THE

PUBLISHER

TO THE

READER.

Custom having made a Preface or Epistle to the Reader almost necessary, I shall so far comply as to give a short account of the following treatises. The reputation of the author is so well established that I shall waive all that might be said upon that head, and only desire the reader to observe that, soon after his death, his papers were committed to my care by his relatives to publish what I thought might prove acceptable to the learned, which I have endeavored to do in this volume.

The tracts published here are for the most part lectures, made and read by him at several different times upon different subjects, which the reader is presented with here just as the author left them. I was unwilling to model or methodize them anew by reducing the subjects and discourses of many lectures into one continuous discourse, as was his method in the treatises formerly published by him in quarto. Much less have I ventured upon any epitome, as abridgments too often distort and curtail the author's true sense, disguising it so that his own sentiments are hard to be distinguished and always dubious—errors I have desired to shun as much as possible. I am sensible that, by publishing his discourses thus at length, some recapitulations have been unavoidable, especially in discourses of this nature, which it is possible may disgust some fastidious critics; nevertheless, I hope the candid reader will not find these repetitions so many or so large as to be dissatisfied, most, if not all of them, containing some new matter added to what was said before.

The subjects handled here are some of the most difficult in natural philosophy natural philosophy, and the discourses were all well accepted and approved of when read before competent judges of the ROYAL SOCIETY at their usual meetings.

The first contains a general scheme or draft of a method for advancing and promoting natural philosophy, showing its present deficiency, with the several queries to be made, and how they may be answered to render it more instructive and beneficial. It must be granted that the last and chief part of this physical algebra physical algebra, or new organ original: "New Organ" — likely a reference to Francis Bacon's Novum Organum. (viz., the method of arranging the experiments and observations in order, so as to frame and raise axioms from them) is wanting—which I believe was never written by the author. However, I make no doubt but what is offered here will prove acceptable for the many curious pieces of information and experiments contained therein.

What follows is a collection of several lectures concerning the nature of light, in which its cause, motion, action, velocity, and properties are largely treated of, with many new, useful, and entertaining subjects, either more copiously handled or hinted in transitu original: "in transitu" — in passing.. Though the author has not in these discourses treated of the several alterations and affections of the rays of light from reflection, inflection, and refraction, etc.,