Epistle Dedicatory
To the Right Honourable John, Earl of Bridgewater, Viscount Bradley, Baron Ellesmorte: One of the Lords of His Majesties most Honourable Privie Council, and Lord Lieutenant of the County of Buckingham.
My Lord, these Works of the Learned Gunter, do naturally and of right, address themselves to your Honours Patronage: having been originally Insignalizes with the Titles of Your Renowned Ancestors, under whom (near Fifty years since) they received their First Life: So that they seem to be Intailed on your Illustrous Family: Especially, considering the whole world owns your Lordship, no less Heir to your Ancestors resplendent Demeans, them of their love to Noble Arts, amongst which those of the Mathematicks, is none of the meanest you are master of.
My Lord, the world taking example by so good a commendum has encouraged this work to this Fifth Edition. But it having met with the ill usage in former Impressions to have contracted several Typographical Sphalmata, which did some what disfigure its beauty, I thought it requisite to bestow some pains in their rmoval, as also to furnish it with attendance of some compleat tracts of Mr. Samuel Foster, our Learned Authors Successor in his Astronomical Profeßion in Greham Colledge: what other Additions I have made to the work in several places, which are not only pertinent, but necessary, the Reader is aquainted in the Preface. My Lord, this work being arrived to this state of Perfection, plead for a bold access to your Honours hands, and makes it humbly confident to find your Honour no leß favourable to it, now grown up, than your Predecessors have been to it in fancy. My Lord, I have derived, likewise, hence some share of that humble confidence, that your Honour will pardon this presumption, of my subscribing my self.
My Lord,
your Lordship most obliged,
and obsequious servant
William Leybourn
William Leybourne to the Reader
I am far from the vanity of desiring to have it thought, that I prefix my Name as a Bush or Garland to invite any to the Purchasing of this Book; The Learned Authors Authotity is mote than I or any other can say for it, and the number of Impressions that have been so welcome by the Publick is a sufficient Testimony of its good acceptance in the World, for indeed, of all the mathematical Books yet extant, I know not one more full of variety of matter, nor more Practical than this is.
All that I design in this Preface is an Apology for my self, to ask pardon of the more knowing mathematician, for my confidence in presuming to shelter any of my means and weak Performances unde the canopy of so profound a master of Mathematical Learning as this our Author was. But to such as shall be offended therewith (as, I hope, none justly can) let me say thus much for my self:
- I am not the first that (with good success) have attempted the like.
- I what I have done in this Work, I have not diminished or expunged one Syllable of the learned Author, but retained his own Method, and the several Examples throughout the Book I have carefully examined, and where I found any Typographical Error, I made bold to correct it, for which, I presume, I derserve rather Thanks than Blame.
- That whatsoever herein I have atttempted to insert, is nothing but what is absolutely pertinent to our Authors Works, and renders his Instrument to young Tyroes in these Scieneces more useful than they could otherwise imagine.
- In what part of this Book soever I have added anything, I have done the Author this right, for in the Content before the Book, relating to the Page wherein any Insertion of mine is, I have before it placed the figure of a hand pointing thus ☞: So that if I have done any thing, misbecoming an Artist, the Author may not be charged with it, but my self justly blamed.
And although, there are here and there some hints of things in several places of the Book of mine inserted, yet principal are these, viz.
- In the Sector, where (after our Author hath trated of Projecting of the Spheres in Plano upon all the principal Spherical Circles) I have added one other Projection upon an Oblique Circle, wherein (if I deceive not my self) I have given more light to Projection in Plano, than is yet extant in our Mother Tongue: for out of this Oblique Projection may be demonstrated the whole Art of Dialling, and in some measure it is there effected.
- In the Cross-Staff (after our Author hath treated of the Mensuration of Plain Regular Superficies) I have inserted the mesuration of such as are not Uniform, as also of Multangulars, Regular Poligons, &c. And (after this Mensuration of regular squared Solids) I have added the mensuration of Prisms, Pyramids, and Cones, both whole and dissected. And with these and such like necessary matters, I have in several other places supplied a Vacancy.
To the second Appendix, which is the use of a Quadrant, of Mr. Samuel Fosters Invention, Printed with the former edition of these aour Authors Works, I have altered nothing, but have added the Construction of the same Quadrant formerly wholly omitted. And in his Alteration of the Sector, I have corrected some Oversights, and mistakes, which were in the former Edition (that being Printed by a Copy less Correct) by the help of Mr. Fosters own Manuscript, which I was accommodated with from the worthy Dr. John Twisden, a most industrious mathematician, and a worthy honourer of the learned Mr. Foster, to whom (not only my self, but) the whole World in general is engaged for his care and pains in the Publication of divers of Mr. Fosters Works with several of his own both in latine and Englsih in a Book Entituled Miscellanies, or Mathematical Lucubrations of Mr. Samuel Foster.
Having thus far declared my self, and endeavoured to take off such asperations as might possibly have been thrown upon me; Give me leave (for the Dead cannot plead for themselves) to take notice of some Plagiaries and Purlciners of other mens Labours and Ingenuities, who out of Lucre to themselves, and Emulation to others of better parts, have lately thrown into the World (to the grand abuse thereof) several trivial Tractates, extracted (or rather transscribed) both from our Author, and also from the Works and Manuscripts of the fore-mentioned Mr. Foster, our Authors Successor in the Astronomy Profeßion in Gresham Colledge, London, Publishing them to the World in their won names, without taking the least notice of the learned Authors, whence they originally filght those ornaments wherewith they pride themselves in their several Pamphlets, not so much as mentioning their with any due respect. I need not tell thee who they be, Their own Impertinencies having made them notoriuous enough; for some of them (rather than they will want applause) become their own Encomiasters, sounding their own Trumpets before their Books, both in Englsich, Greek, and latine. But leaving these to just censure of all that shall take due notice of them, give me leave to commend thee to the perusal of these Works of our Judicious Authors, in the Use and Practice whereof (as in all other thy honest Attempts and Endeavours) I wish thee good success, and for this time bid thee
Farewel.
Arpil 18. 1673
