PREFACE.
Mathematical Form; they may refreſh their Memories with ſome things they have forgot or remember but imperfectly.
It may alſo be of uſe to thoſe who are juſt entring upon the Study of Natural Philoſophy, as they will find the Laws of Motion, which are the Foundations of that Science, more largely explained than is commonly done; which, when thoroughly apprehended, will prove a great Advance to more difficult Speculations.
There is another ſort of Perſons, whom I had in my eye, and would be very glad to benefits "Which are induſtrious and dextrous Workmen. Of theſe I have known ſeveral, who would be well pleaſed to underſtand the Nature of thoſe Machines which they daily uſe, but underſtand no otherwiſe than by Uſe. Such Perſons will I believe be well contented to find the Reaſons here explained of ſſeveral Things, which they do at preſent only becauſe they have ſeen them done before. I can but think, that with ſome Things they don't apprehend, they will find others that they may, and
