Querela Geometrica: OR, GEOMETRY'S Complaint Of the Injuries lately received from Mr. THOMAS VVHITE In his late Tract, Entituled, Tutela Geometrica.

In the end you have some Places at large out of Mr. White's TUTELA, and Gulden's CENTRO­BARYCA, Reprinted, and faithfully Translated into English.

LONDON, Printed by R. W. 1660.

The Publisher TO THE READER.

HAving in the following Letter from my Friend, receiv'd a brief account of Mr. Whites so much fam'd and expected Geometrical Treatise, I thought fit to publish it for satisfaction of many, very desirous to understand the success he has had therein.

Know then, that the Letter consists of two parts. The first demonstrates the many and gross Errors against Geome­try, committed by Mr. White in his Tutela Geometrica: which yet he terms his Chrysaspis, or Golden Shield, wherewith to defend all his other Works.

The latter part layes open his most un­worthy proceeding against a famous Ma­thematician, by charging him with many and evidently false imputations, on pur­pose to disgrace him. From all which he is here fully vindicated, as well in the en­suing Letter, as in the Additionals.

Querela Geometrica: OR, Geometry's Complaint Of the Injuries received lately from TUTELA GEOMETRICA. OR, The Copy of a Missive, &c.

SIR,

I Have, according to your re­quest, perused the small Ge­ometrical Tract lately pub­lished by Mr. Thomas White: whereof accordingly I give you here this brief account. The in­tent and occasion of his present Writing, as on this Subject, [Page 4] (having scarce hitherto appeared in that kinde) is (as is manifest by the Title) to make known to the world the great light he hath received particularly from God in that noble Science of Geome­try; as having never studied it, nor much applied himself that way: that thereby other men, conceiving this so excellent a Piece must needs have been con­veighed to him by particular light from Heaven, may learn thence more to prize and esteem, then hitherto they have done, his Works already published. For so he tells his Reader in the end of his Preface, that the things he is now to declare, ought to be sufficient to give esteem to all his former Labours. For if (saith he) they came from the Author, and from that force and vigour of Wit, by which he is able to per­form many more equal to this, [Page 5] then his precedent Works are not to be contemned, as pro­ceeding from such a Father, quia de tali exorta sunt Patre: But if it come from Heaven, then much more are his other Works wor­thy consideration, to wit, as co­ming also from Heaven before it.

Now that they come not from himself, he openly avouches, as having never had any Master in Geometry, nor much applied himself to that Science, or read so much as Euclide. Yea, he free­ly acknowledges himself so little versed in Geometry, that he plainly affirms, no man will call him a Geometrician, if he be one himself: Intuere me hominem, quem nemo Geometram salutet, mo­dò ipse sit. Whence he concludes, that the things he is now to de­liver, must assuredly come from Heaven: Talis cum sim, non à me haec habes, sed ab eo, qui ex legibus [Page 6] Providentiae suae, ea gubernationi Ecclesiae suae, in hoc rerum ar­ticulo, opportuna & fecit, & vi­dit. Being I am such a one; (to wit, so little vers'd in Geometry) thou hast not these things from me, but from him, who accord­ing to the Laws of his Provi­dence, both saw and made them fit for the Government of his Church, in this present conjun­cture: give him the thanks, &c. Wherefore he exhorts the Rea­der, not to neglect his own good, nor contemn a wonder fallen to him from Heaven. Quod superest, tibi consule, & ostentum a caelo ad te delapsum ne contemnito.

All this with some other such expressions hath Mr. White in his Preface; whereby you clearly see, how highly he values this his Tract, as fallen from Hea­ven, and accordingly desires the like esteem should be framed of [Page 7] all his other Works: that so his Readers considering and weigh­ing with themselves, that it is im­possible so learned and subtil a work should come from one that never studyed Geometry, must necessarily conclude that it came particularly from Heaven: and by consequence also have a better esteem, then hitherto, of his for­mer Labours, as undoubtedly coming from the same place.

This is the aim and drift of Mr. White in this his Tutela; wherein truly he seems, by so far expressing himself, to have given a very great advantage to who­soever will impugne his former Writings. For now his Adver­sary hath no more to do, but to shew (as easily he may) that this Geometry never came from Hea­ven, and by consequence, that neither any of his former Works, (whereof Mr. White would have [Page 8] this to be a pattern according to which they are to be measured) ever came from thence. This I say he will easily make manifest; for it is impossible, that ever so weak a piece, as this is, and with so many Patent and open er­rors against Geometry (as we shall presently see) should ever come from any Geometrician, much less from Heaven. Which that it may appear, we will brief­ly run over the Propositions, as they are in the Book, to see which of them may deserve to be thought to have particularly de­scended from Heaven: and then note onely some more patent and obvious errors, such as you your self may easily conceive: by which you may guess at the rest, and what can be here expected.

His Treatise then contains in all thirteen Propositions; of which the two first onely expli­cate [Page 9] the tearms he is to use. The two next are taken out of his Brother, Mr.Richard Whites Book called Hemisphaerium dissectum, as he also acknowledges; so that cer­tain it is, that these first four came not from Heaven. The five fol­lowing aim at the Quadratura Circuli, but perform no more then a hypothetical, or conditio­nate Quadrature: that is, if such or such a proportion were known, it were possible to square a circle; but of such Quadratures as these, we have enough alrea­dy, and books are every where full of them. For the rest, I finde nothing in these propositions truly demonstrated, that may not be found in other Authors: so that in these nine first Propositi­tions, we have nothing that may be thought a wonder fallen from Heaven, as was promised.

In the Annotation before the [Page 10] tenth Proposition he endeavours to demonstrate, that a Spiral line of the first revolution is precise­ly equal to half the circumfe­rence of the including circle. For example that the Spiral, noted here by the pricked line EABCMGHID, is equal to the half circumference, DQR. This Demonstration indeed seems to have somewhat of the extraordinary in it: but yet it is neither new, nor true; and so impossible it should come from Heaven. For this self-same De­monstration was found out above thirty years ago by one Gulden a Jesuite: and is to be seen in his Book, called Centrobaryca, or, De centro Gravitatis; as Mr. White here also acknowledges. This Demonstration, I say, Gulden found out, and shews in the said Book, lib. 2. c. 2. prop. 6. But afterwards, before the Book was

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[Page] [Page 11] printed, being advertised of the falsity found out by calculation, and perceiving it to be so, he pre­sently recalled the same in the next Chapter, and clearly shews, that not onely the Spiral line it self is bigger then the said half circle, to which before he thought it was equal; but also evidently shews, that the sides of an inscribed Polygone of twelve Angles is also bigger then the said half circumference, as I shall afterwards declare.

Of this Guldens recalling Mr. White (as himself testifies) was by some friends informed; but not being able, as it seems, to exa­mine Guldens calculation, nor to see the force of it, he presumed to print the said Demonstration, as his own, and to maintain it to be good, and evident, and Guldens calculation, or retractation, to be manifestly false, as we shall pre­sently see.

This Demonstration I say, Mr. White let pass to the print; yet conceiving, as it seems, that people would still think it to be taken out of Gulden, it being the very same with his, he thought good to joyn thereto another of his own, demonstrating the same assertion, in a different way from the former; which he performs in the tenth and eleventh Propo­sitions. And certain it is, that this Demonstration is wholly his own, that is, that it neither came from Heaven, nor from any other Geometrician; it being impos­sible, that so many and patent er­rors should come from any that ever studyed Geometry, or read so much as Euclide; or even knew but how to resolve a plain Triangle.

For in the tenth Proposition he affirms and pretends to de­monstrate, first, that if in a [Page 13] Spiral line of the first revolution, be inscribed a Polygone with e­qual angles, (as in the adjoyned Diagram, you see here inscribed the Polygone EABCMGHID, with eight equal angles) that then the sides of the said Polygone shall equally exceed each other: that is, as much as DI exceeds IH, so much pre­cisely shall IH exceed HG, and HG exceed GM; and so of the rest.

Secondly, he affirms this com­mon excess to be equal to the least side of all; viz. to the side EA. These two Assertions he puts in the Title of the said tenth Prop. which is this, Latera Poly­goni inscripti spirali per aequales angulos exuperant sese invicem per excessus minimo lateri aequales.

Thirdly he likewise affirms, that having let down from the points I, H, G, M, &c. Perpen­diculars [Page 14] to the opposite Semidi­ameters, (as here you see let down the Perpendiculars IK, HF, GL, &c.) that then the parts of the said Semidiameters, inter­cepted between the Perpendicu­lars and the Spiral, that is, the parts KD, IF, GL, and so of the rest, shall be equall. This third he inferres (though falsely, as presently we shall see) about the middle of the said tenth Prop. in these words, Aequales itaque sunt rectae KD, IF, & HL. all which three Assertions are evidently false, as I shall briefly shew.

For if we put the Semidiame­ter ED (which according to the construction of the Spiral, is here supposed to be divided into eight equal parts) to contain 800 equal parts; the next EI will contain 700: and EH will have 600, and EG 500, and so forward: [Page 15] So that the first EA will have 100, and EB 200, &c.

Whereby we have now in every Triangle EDI, EIH, EHG, &c. two sides known, to­gether with the angle compre­hended.

For example, in the Triangle EDI, we have the side ED 800, and E I 700, together with the comprehended angle DEI of 45 degrees. So likewise in the Triangle EIH, we have E I 700, EH 600, and the angle IEH 45 degrees as before; and so of all the rest. Which being known, we may presently by re­solving the said Triangles, finde the two last sides of the inscribed Polygone, to wit DI, and IH, to contain the one 581, and the other 505, whose difference or excess is 76. But if in the same manner we resolve the first Tri­angle EAB, we shall finde the [Page 16] second side AB to be onely 147; from whence being taken the first side EA 100, shews the dif­ference between the first and se­cond side to be onely 47. And so in like manner will the diffe­rence between the second and third, AB and BC be onely 65. Now these three differences or excesses, 76, 47, and 65, are far from being equal, as Mr. White would have them. Wherefore in this he must needs confess him­self quite mistaken, and his de­monstration thereof to be false.

Neither is his errour less noto­rious in affirming the said excess, (which he also falsely supposes to be common to all) to be equal to the least side, that is, to the side EA: for EA being 100, is bigger then any of them all, as we have seen. Yea, he is so inex­cusable in this, that his very eyes might have discovered the error.

His third Assertion is also as false and unexcusable, to wit, that the lines KD, FI, LH, &c. are all equal. For resolving the Triangles EIK, EHF, and EGL (in which you have a side with all the Angels) you will finde EK 495. EF 424. and EL 353 which being respe­ctively substracted from ED 800 EI 700. and EH 600, leave KD 305, FI 276, and LH 247. which three numbers are also far (as you see) from being equal, as Mr. White pretends to have de­demonstrated. Wherefore we must needs here conclude, that such Demonstrations as these never came from Heaven, as Mr. White perswades himself, and would have us believe. And [...]ruly whosoever reads this his tenth Prop. will clearly see his want of Principles, and that he was fallen upon a business he un­derstood [Page 18] not: wherein he was so puzzelled, that he quite forgot what he had said he would prove, to wit, that the said com­mon excess was equal to the least side: for of this, after he had put it in the title, he makes no more mention, nor once goes about to prove it.

Now out of so weak and false a ground as this of the tenth Prop. he demonstrates in the eleventh (at least he thinks so) that the Spiral line EABCMGHID, is equal to the half circumference DQR: but a­gain performs it so unskilfully, that although the ground now laid in the tenth were true, yet follows not his intent. For by shewing onely that it is not big­ger, he inferrs it to be equal; which is no consequence, al­though the Antecedent were true: but both the one and the [Page 19] other are false, as we shall pre­sently see.

Now after so weak and false a Demonstration, by which he thinks he hath concluded the said Spiral and half circumference to be equal, he proceeds in the twelfth Prop. to refute Gulden; who recalling (as was said) this very Demonstration, (which now Mr. White pretends to be his own, and maintains to be good) clearly shews, that not onely the Spiral it self is bigger then the said half circumference; but also an inscribed Polygone, for example of twelve equal an­gles, is considerably bigger.

To confute this assertion of Gulden, Mr. White puts his twelfth Prop. wherein he pre­tends to demonstrate against Gul­den, that the sides of such a Po­lygone being added together are [Page 20] less then the said half circumfe­rence: but truly with a Demon­stration like the rest, that is most false and frivolous. For having put the line EC in the Dia­gram of the said twelfth Prop (which Diagram I have here ad­joyned) to be the greatest side of a Polygone inscribed with twelve equal angles, he supposes that the same longest side EC being taken six times, will be equall to all the sides of the said Polygone added together: for so he writes a little after the be­ginning of the aforesaid twelfth Prop. Clarum est itaque, EC sexies repititam, hoc est figuram in­scriptam spirali, esse majorem, &c. Whereby you see that according to Mr. White it is all one, to take the longest side of such a Poly­gone six times, or to take the whole inscribed figure, that is,

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[Page] [Page 21] all the twelve sides added toge­ther: which notwithstanding is most false. For if we put the Semidiameter DB, or DC to be 12000, we shall have in the Triangle DEC two sides known, to wit DC 12000, and DE 11000, together with the angle EDC grad. 30. From whence is evidently concluded EC to have 6031. (I omit here alwayes the Fraction as making not to our present purpose) which number taken six times makes onely 36186: whereas all the twelve sides, found out in the same manner and added together, make 40003, as appears in the Table here adjoyned. So that in this supposition Mr. White is quite out.

Yet notwithstanding this false supposition, he goes forward to demonstrate against Gulden, that [Page 22] the sides of such a Polygone ad­ded together are less then the half circumference; which he per­forms so confusedly, and unskil­fully, that it is impossible to infer any thing to his purpose out of such a discourse. But be the dis­course what it will, at last he strongly concludes against Gul­den, that the sides of the said Po­lygone are less then the half cir­cumference.

But this his conclusion is most false, as Gulden hath evidently shewn, lib. 2. c. 3. prop. 1. and may be so apprehended by any man that knows but how to re­solve a plain Triangle. For by finding every of the twelve sides of the Polygone in such manner, as we now found the twelfth or longest side EC to be 6031. we shall have all their numbers, as appears in the here adjoyn­ed [Page 23] Table;

126031
115520
105011
94505
84001
73501
63006
52522
42053
31614
21239
11000
Summa lat40003
Semiperiph37715
Differentia2288

all which added together, make, as you see, 40003. Whereas if according to Archi­medes, you number the said half Cir­cumference, by ta­king the said Se­midiameter ED 12000 thrice with its seventh part, we shall finde the said half cir­cumference to contain at most on­ly 37715: which is far less then 40003. And by consequence the sides of a twelve angled Poly­gone inscribed in a Spiral, are absolutely longer then half the circumference of the first circle, as Gulden truly and learnedly shews against Mr. Whites so weak [Page 24] a Demonstration for the contra­ry, as we have seen.

By these discoveries of so ma­ny undeniable errours in his Ageometricall Demonstration, one would judge that Mr. White had the least reason of all others to censure any one; yet such is his passion, that he falls bitterly upon Gulden, censures, vilifies, and reviles him insufferably, calling his Computation unskilfull, and that he hath not a jot of Mathe­matick or Geometry in him; terming him one of those half Schollars, who stealing divers excellent things out of other Learned mens Writings, endea­vour to make them seem their own. This bitter invective hath Mr. White against Gulden, a man who never had in the least of­fended him, perhaps never heard of him, being dead many years [Page 25] since, and so not able now to an­swer for himself. Take Mr. Whites own words at the end of his twelfth Proposition. Calculus itaque Guldenianus imperitus est, & qualem ab ipso acceptari (neque enim vel talem ipse instruxit) dece­bat: Homine prorsus Amathema­tico, ut legenti ipsius scripta pro­num est patere. And a little af­ter having taxed his want of hu­mility and candor, he concludes him to be, Hominem officij Geo­metricij prorsus ignarum; & ex eo semidoctorum genere, qui cum ex magnorum virorum scriptis egre­gia multa depeculati fuerint, ut sua faciant, additis quibusdam levibus, justi voluminis ostentatione se vul­go discentium ostentant, &c. This gall, whilest Mr. White flourish­ed amongst his admirers with his new Demonstration, might have affixed some seeming ble­mish upon Gulden, amongst such [Page 26] Ageometricians as Mr. White is, but now appearing by what is said, to proceed from so unskilful a hand, it cannot tend to the dis­grace of any, save the censurer, who condemns that which he understands not. For certainly no Geometrician would or durst have said so much; the Compu­tation being performed accord­ing to the 47. 1. Euclidis, by the extraction of the square Root; then which there can be none more exact and manifest. As for that he calls him Semidoctus, a half Schollar, one utterly void of all Mathematick; that he hath stolen out of other mens works; and all this immediate­ly after so many errors commit­ted by himself, he hath put the lash into the hands of such, who if they please, will quickly know to use it; especially being so justly provoked by seeing one of [Page 27] their own Order so wrongfully abused; and will not fail to re­tort upon him all that he impo­ses upon Gulden. And truly who­soever shall read this Geometri­cal Treatise (which Mr. White esteems the master-piece of all that ever he hath writ) and Gul­dens Book called Centrobaryca, will finde so main a difference, that Mr. White without any pre­judice, by what appears in his, may be scarce thought fit to be Guldens Schollar.

And whereas he calls Gulden one of those half Schollars, who steal out of other Books, they will easily make it appear, that, whatsoever it be of Gulden, cer­tain it is, that Mr. White hath stolen that Demonstration out of Gulden. For even by his own confession it came not from him­self; Non à me haec habes, &c. and to say it came from Heaven, [Page 28] were a blasphemy, it being mani­festly false, as we have seen: Wherefore it must necessarily be concluded, that Mr. White took it out of Gulden, who printed it many years ago, as a particular invention of his own; neither can any other Authour be cited, who published it before him.

Truly a man would think Mr. White to have already said more then enough in so vilifying, and even trampling upon this Au­thor, especially there appearing no cause for such bitterness. But he is not satisfied to have thus disgraced him, as much as lies in his power, with the note of igno­rance in the Science he professes; but he falls upon his Moral Ver­tues, taxing him of Vanity, want of Humility, Candour, and the like, affirming him to be so vain, that although he thought he had committed an errour, (to wit, in his [Page 29] Demonstration of the Spiral) yet he could by no means be induced to co­ver it, by blotting it out, or candid­ly to confess the same, but goes on, framing excuses, as if in the very errour he had carried himself gal­lantly. Master Whites words are these in the place now cited: Et (quod faedissimum est) tantae va­nitatis est, ut cum erravisse se pu­taverat, neque delendo tegere, ne­que candidè confiteri sustinuerit; sed excusationes texere, quasi in ipso errore egregiè se gesserit, ostentare pergat, &c.

O most unworthy and false ca­lumny! when I had read these in Mr. white, and compared them with what Gulden sayes in recal­ling the said Demonstration of the Spiral, I was amazed, how Mr. White did not even blush when he writ so foul and evident an untruth. For of all that, which he so maliciously here imputes [Page 30] unto this man, there is not one word to be seen in Gulden, nor the least ground or shadow in his writings; yea, the just contrary to what is here so shamefully avouched, doth manifestly ap­pear, as any man may see in his Book called Centrobaryca, cited by Mr. white. Where lib. 2. c. 3. re­tracting the said Demonstrati­on, he plainly tells the occasion of it; viz. that being informed that a certain Mathematician had by Calculation discovered an errour in his Demonstration, al­though at first it made no great impression in him, for he thought himself so secure, that he hoped sooner to finde a thousand errors in that Mathematicians Calcu­lation, then one in his own De­monstration: Mille potius spera­bam me in Calculo hujus examinis, inventurum errores, quàm vel uni­cum in meis inventis; sed contra [Page 31] quasi accidit, &c. But I found, sayes he, just the contrary. For having examined the said Calcu­lation, I clearly saw the errour, and was forced to confess it, Victus debui dare manus. Where­upon he presently retracts it, and is so far from excusing the error, or refusing to confess it, or brag­ging as if he had carried himself gallantly therein, (as Mr. White most falsely and injuriously im­poses upon him) that he plainly and candidly confesses it, saying, that he had rather follow the ex­ample of other worthy Authors, who in like case have, to their own praise and profit of others, revoked their errours, then of such as had rather accuse Archi­medes, Euclide, yea, Geometry it self, then once acknowledge the errours of which they were con­vinced.

As to that whereof Mr. White [Page 32] most wrongfully taxes him (in those words neque delendo tege­re) for printing the said Demon­stration, although he thought it to be false, Gulden gives there also the reason, why he printed it: to wit, that others seeing how he had erred in a Demon­stration, which at first sight seem­ed so currant, might beware of the like fallacy: Ut sciant sibi ca­vere a scopulis.

By all which is most evident, that it was ignorance, and pas­sion, and neither knowledge, nor reason, which extorted these ugly censures from Mr. White against Gulden: and how far that Au­thor was from that vanity and stubbornness in maintaining what he had once asserted, though he thought it to be false, as Mr. White would make the world believe. For I dare main­tain, that there is not an Author [Page 33] to be found, who in the like case hath carryed himself more mo­destly and candidly then this man hath done: as any, who shall read the said third As you may see at the end of this Letter. chapter, will, to Guldens praise and Mr. Whites confusion, plainly disco­ver. And God grant Mr. White may but with as much humility recall and acknowledge what he hath written amiss in matters of more concern, as this man does retract his Mathematical error.

Wherefore in this so much vilifying of Gulden, he hath again put the lash into his adver­saries hands, who may use it at their pleasure, and make known unto the world, that no man that had any worth in him, con­science, or moral honesty, would ever so unworthily have carried himself as Mr. White hath in this. Yea, they may, if they please, re­tort all that he so wrongfully [Page 34] layes upon Gulden, most justly upon Mr. white: making it ap­pear, that he is rather to be taxed of vanity, as having gotten one­ly some few Tearms of Geome­try, (and yet more then he knows well how to use) would fain have the glory of a Mathemati­cian. For although with the one hand he seems to drive it away, yet with the other he draws it to him, as any man but reading his Preface will clearly see. For al­though he tell his Reader, that he is no Geometrician; and that these so great things (as he fan­cies them) come not from him­self but from God; Non à me haec habes, &c. yet he would have him withall to take notice and well understand, that he is also able even by the force of his natural wit, to perform as great things as these are. For speaking of himself and what he is to deli­ver [Page 35] in the said Geometrical Tract, he writes thus: Author vel suâ industriâ perfecit quae of­fort, vel privilegio magnae Pro­videntiae accepit. Si à se, & inge­nij eâ virtute, qua plura ejusmodi conficere in parato habeat, certè is est, ut non sint contemnenda illa cae­tera, quae in publicum usum elabo­ravit, &c. Whereby you see, he plainly tells his Reader, that he hath now already in store di­vers other things, as good as these. Plura ejusmodi in parato ha­bet. And these also found out by the vigour and strength of his own wit. Eâ ingenij virtute, qua, &c. Yea although he tells his Reader, that he most onely thank God for these wonderfull things; and that in thanking the Author he shall do him injury, and lay a burden on his shoulders more then he is able to bear: Mi­hi si grataris, injuriarum te postulo, [Page 36] quod plus in me oneris aggeras, quam cui sim ferendo. Notwith­standing he plainly shews by what you have heard, that he is ready and able to bear more thanks, then I believe his Rea­der will give him: especially when he shall perceive himself deluded in the Preface, with ex­pectation of wonders from Hea­ven, and when all is done, find­ing nothing worth the reading.

But Mr. White is not content with so much depressing this Au­thor, but passes further, branding him with the badge of an Here­retick, or worse; intimating him to be one of that pernicious Sect of Pedants, who by their pra­ting, labour and endeavour to de­stroy not onely all humane Sci­ences, but even Christian Faith it self, by taking all certainty from them. For giving a reason why he so much enveighs against [Page 37] a man wholly unknown to him, he presently adds, Quantumvis operae pretium erat, lectorem moni­tum reddere de exitiali hac sciolo­rum secta, quae sub professione fa­cultatis garriendi, omnem certitu­dinem, tum è scientiis, tum ex fide Christianâ tollere molitur. Here Mr. White stops; and truly it was time: for having forgot what he first intended, to wit, to draw out a perfect picture of Gulden, he hath mistaken the colours, and goes on drawing forth his own, as any man that ever knew them both, will evidently discover.

Now if you ask me what was the main cause, that moved Mr. White to this height of passion, he himself tells you, to wit, that he was forced and compelled to utter those censures. And why? Because the shadow (as he sayes) of Guldens great Tome did hin­der his Scholars from embra­cing [Page 38] the truth (he should have said the falsity) he proposed to them. For so he writes in the place before cited. Haec coactus sum de homine caeteroqui ignoto prodere, quia umbra Tomi illustris, per opinionem consequam, officiebat veritati, quam ejusdem studiosis offerebam. In which words I should rather think Mr. White to have wronged his Scholars, in making them such as should be frighted with a shadow. But it seems more probable, that his Scholars better understood the force of Guldens Computati­on, then their Master either would or could, and saw clearly that it did conclude. Howso­ever it is most strange, that any wise man for so frivolous a toy as this, should so highly offend both Almighty God and his Neighbour, and so evidently expose his own reputation to the [Page 39] unavoidable stain of a notorious Detractour.

Truly, as it seems to me, in this the particular hand of God shews it self, as well for his own good, (if he will make use of it) as for the good of others: in per­mitting Mr. White so to cross his own designs, that whereas he thought in this Tract to advance himself and his former writings, in the repute of every one, he should finde the quite contrary. For whereas he thought thereby to have got the name of a great Mathematician, he hath clearly shewed that he is none; and that he is indeed onely furnished with such general Terms and common Notions in the Mathematicks, as being with confidence and boldnesse pronounced in the company of such, as do no more thorowly understand them then himself, are apt to produce in [Page 40] their mindes, an opinion, that the pronouncer is certainly a learned man, & understands exactly what they hear so strongly assevered by him: whereas if some learned Mathematician should perhaps over hear him he would smile to hear so much Geometrical Non­sense. Nay, whereas he assured himself to conciliate an immove­able authority to all his former Dictates amongst his admirers, by this unparalleld Demonstra­tion, even some of them (as I am certainly informed) have disco­vered the weakness of it, and both blush to see it, and labour to hide it. In like manner, whereas (by vertue of his said Tutela) he aimed to be accounted a person whom Almighty God particularly designed to use as his Instrument for the governing of his Church in this present con­juncture; and to this effect, to [Page 41] have received great light and In­fused knowledge from him, as we have heard him speak in his Preface; he hath now given such a Character of himself, that it is impossible, that any man should be so simple as to think, that the wisdom of God would particu­larly make choice of such an In­strument for so high a Work; to which men of far greater Chari­ty and Perfection of Vertue then he can with any reason or ground be supposed to have, are wont to be called.

This unworthy proceeding of Mr. White had made me almost forget to refute his Quadratura Circuli, pretended to be shewen in the first nine Propositions: which I deferred to the last, because he in his thirteenth and last Propo­sition hath put the last hand thereunto, and so confirmed as he thinks the ground thereof, that [Page 42] he supposes it now as evident (to use his own phrase)as that a Boat is a Boat.

Wherefore in this thirteenth Prop. he again affirms, what he had before averred in the sixth; to wit, that the Segments, or Por­tions of unequal circles, having the same Chord, (so that they be less then a Semicircle) are propor­tional to their Axes. Portiones circulorum inaequalium, semicircu­lo minores, quarum subtensae sunt oequales, sunt in ratione suorum axi­um. For example, in the adjoyn­ed Diagram, he affirms, that the greater Segment BFCB hath the same proportion to the les­ser Segment BDCB, that the greater Axis F G hath to the lesser DG. This is the ground of his Quadratura, which we will now shew to be most false, and by consequence, the whole building to fall. Which

[Page]

[Page] [Page 43] that it may the more clearly ap­pear, let us suppose EB or EF the Semidiameter of the greater Segment BFCB, to be 1000, and his angle at the Center, BEC, to be 120 degrees, or the third part of the whole circle BFC: which being supposed we have.

  • 1. EG 500, as being the Sine of the angle EBC 30 de­grees, and by consequence the greater Axis GF is also 500.
  • 2. By the usual proportion of the Diameter to the circumfe­rence we shall finde the Sector E B F C, being the third part of the whole circle, to contain 10476191/21.
  • 3. By the Perpendicular EG 500, and the half base GB 866, or Sine of 60 degree. We shall finde the Triangle EBC to contain 433000: which being subtracted from 10476191/21 the [Page 44] whole Sector, leaves 614619 [...] for the greater Segment BFCB.

In like manner, if we put AB the Semidiameter of the lesser Segment BDCB to be 2000, that is, double to EB, we shall finde

  • 1. By the 47. 1. Eucl. AG 18027/9 proximè: which taken from A 2000, leaves 1972/9 for the lesser Axis GD.
  • 2. By what is known in the Triangle ABE we shall finde the angle BAE, whose double shews the whole angle of the Sector ABDC, to be 51 degr. 19′ 30″ from whence by pro­portion thereof to 360 degr. is found the Sector ABDC to contain 1792126.
  • 3. By the Perpendicular AG 18027/9, and the half base BG 866, is found the Triangle ABC to contain 15612051/9 which being taken from the [Page 45] whole Sector 1792126, leaves 2309204/9 for the lesser Segment BDCB.

So that now we have the said Segments and their Axes, all four in numbers, to wit, the greater Axis 500, the lesser 1972/9 the greater Segment 6146191/21 and the lesser 2309204/9 which four numbers are by no means pro­portional, as they should be, if Mr. Whites Demonstration were true. For by saying as 500 to 1972/9 so 6146191/21 to a fourth, there will not be found (as was expected) 2309204/9 but another number far bigger, to wit, 2424331/3 the difference being (as you see) 115128/9. Which great difference shews evidently the falsity of Mr. Whites Assertion. Yea, if we put the greater Seg­mentto want but very little of a Semicircle, for example onely one Minute, or one Second, &c. [Page 46] the errour will be yet more noto­rious, and the proof more easie. For then the greater Axis will be 1000 Proximè, and the greater Segment will be 1571428: the lesser Axis will be 268: and the lesser Segment 363238. which four numbers are yet far more disproportional: for by saying as 100 to 268: so 1571428 to a fourth, we shall finde 411142, which is greater then 363238 by 47904, almost an eighth part of the lesser Segment. So Mr. Whites Demonstration of the Quadratura comes to just no­thing. But this is like the rest: for with him Demonstrations are nothing but stout and undaunt­ed asseverations, proved by a company of Terms (that make a shew of learning to the unlearn­ed) jumbled at a venture toge­ther.

Some perhaps, to excuse this [Page 47] so gross an errour of Mr. Whites, will say, that by Portiones Circu­lorum he meant not the Seg­ments, as we have said, but one­ly the Arches or Circular Lines BFC and BDC. But this explication will not suffice: for neither had this been to his pur­pose for the Quadratura: nor in it self is it true. For neither are these Arches proportional to the said Axes; the one BFC being 20955/21 and the other BDC be­ing 17921/2 which numbers have by no means the same proportion that 500 hath to 1972/9 as a blinde man may see. Wherefore Mr. White must be content to lay up this Errour with the rest.

And thus much, Honoured Sir, concerning such things as Mr. White pretended here to demon­strate, but hath not performed. But if you ask me what he hath in this little Treatise truly and [Page 48] clearly demonstrated, I can one­ly answer, that he hath demon­strated, first that he hath a great deal of vanity: secondly, that he hath very little or no Geometry: and thirdly, that he hath as little or less charity. For the rest, I have no more to say at present, but hoping you will rather reflect upon what is here said, then up­on the rude and unpolisht Style by which it is exprest, I remain

Your humble Servant.

The Publisher TO THE READER.

HAving Printed the precedent Letter, and understanding before the publishing of it, that Mr. Whites Tutela so often mentioned, was supprest, no more Copyes to be had, whereby the Reader might receive satisfaction in conferring what is here said, with the Authors own words: I thought good to annex such places, verbatim out of Mr. Whites Book, as are touched in the said Letter. To which purpose I have also adjoyned Guldens Retracta­tion of his Spiral, taken out of his Book, de Centro Gravitatis, the Book it self being dear, and scarce to be got. I have put both these, first in Latine, as [Page 50] they were written by the Authours: next in English, because the precedent Letter mentioning them, is also in En­glish. And first I will set down Mr. Whites Preface to the Reader, there be­ing first mention made of it in the pre­cedent Letter. Which Preface is to be seen in the beginning of the said Book, to which he frames this Title,

CHRYSASPIS, Seu Scriptorum suorum in Scientiis ob­scurioribus Apologiae vice propalata TUTELA GEOMETRICA Ad Lectorem Cordatum & Serium.

ARistotelis (dicam, an Naturae?) pomaeria extenderat Digbaeus E­ques, coactis in pellucida stativa Natu­rae partibus, quas turbidè miscuerat generationum necessitas. Solum, fun­datura Substructiones, occupaverat quanti ipsa moles, rari densique suprà serpentium ludis tessellata. Proximo sese exposuit gradu fraterna elemento­rum [Page 51] acies, primis (ut appellant) arma­ta qualitatibus. Haec obnixis in alter­nam internecionem frontibus, consan­guineo cruore quanti aream, ad inex­haustam mixtorum ubertatem per ad­mirandos & inscrutabiles plexus ebul­liendam irrigant & faecundant. Orna­bant mixta Phrygionatae secundarum qualitatum Texturae; accendebant Actionis & Passionis emicantia & hu­manum contuitum obtundentia lumina. Sed neque Electricorum assultus & re­sultus, neque Magneticorum in Homo­geneo corpore mutabiles quasi consultò leges; neque Sympatheticorum ex insi­diis dolosa & tenebricosa è longinquo Sagittatio, origines & semitas suas à tam acri vestigatore celare valuêrunt. Quin & ad superiora sedilia mixtorum capita plantae ascenderunt, & gradum ad ani­malia promoverunt. Hic se objecêrunt scrutino sensus & sensuum metae, vene­nerandi quodammodo naturae limites: & superati scrutatoris oculum in arcana Animae, & invisum orbem trajecêre. Substitit in hâc altitudine Digbaeus, materiam & materiatorum universita­tem tanto à se intervallo in imum dissi­tam, non sine horrore despectans; & no­bilissimo [Page 52] operi, cui de Immortalitate Animae nomen fecerat, columnas appo­suit. Tantus erat Scientiae fulgor, ut lippitudini saeculi caecitatem adjiceret, & furebant vanitatis, quae in multiloquio efflorescit, amatores veritatis imaginem non sustinentes, & potioribus haec scien­tiis adversari jactiabant.

Proptereà necessarius erat aliarum Disciplinarum consensus, & rudem ac­ceptaverat ingentis illius opificii Author. Inventus sum, qui etsi Eloquentiae De­cessoris impar & compendio natus, au­derem desideratorum Epitomen aggredi, & contractis, quae fusius Digbaeus, & pro rerum qualitate disputaverat; ad­jectis (que) Metaphysicâ tum corporum tum incorporeorum delineatione, Institutiones Peripateticas conderem. Adjeci & Sa­cras, & opuscula (quamvis nihil meum opusculi molem excedat) nonnulla Phi­losophica, de Mundo Dialogum, & praefationem ante Latinam Editionem operis Digbaeani. Theologicam quoque Buccinam de Fidei & Theologiae Natu­râ; & ejusdem defensionem adversus errorem cujusdam Regularis de Persona­li Infallibilitate Papae. Praeterea de Gratiae cum libertate consensu, & me­dio [Page 53] Animarum statu singula Commen­tariola. Non mirum, si haec duriùs excepta sint, quam Digbaeani labores. Cum & infaeliciori stylo sint exarata, & iter caecioribus obfessum scopulis & ma­gis affectuum tempestatibus objectum terant. Sed idcircò maximè, quod in omnibus Physicam, Metaphysicam, & ipsam Theologiam, inaudito conamine ad severiores Disciplinas adjungere, & Architectonicam contignationem perspe­ctabilem in toto processu, & dictorum consensum & consequentiarum fidem (nihilominus citra rigoris Geometrici ostentationem) in eas inducere tentave­rim. Quare hunc desiderari suspicatus duos Euclidas, Physicum majorem natu, adolescentiorem Metaphysicum effudi, non vanae spei futuros vades. Verum enim verò etiam hanc evidentiam obsti­natâ incredulitate opprimi sum exper­tus. Quid super mihi reliqueram? Me­mineram à Novatoribus fidei posci mi­racula. Sed ad ea quae suâ evidentiâ sta­bilienda erant, flagitare argumenta ul­trà vim naturae posita propudiosum erat: attamen si quae in Scientiarum Thesau­ris admiranda laterent miraculis suppa­ria, non immeritò ad difficiliorum fidem [Page 54] adhiberi consentaneum erat. Conjeci itaque oculos in Geometriam, cujus si qua dogmata hujusmodi veneratione consecrata laterent, ea neque alienis ad famam praesidiis indigerent, & suo mu­nitis sigillo fidem conciliarent. Et ad­verti reservata quaedam ab ipsa usque Disciplinae infantiâ arcana, quae maxi­morum ingeniorum labores passa in im­possibiliam transiverant classem. Pap­pus & plerique posteriores Geometrae tres Problematum ordines declarave­rant; quorum infimus regulâ & circino perficiebatur; medius corporum sectili­um vi; supremum non nisi fictitiis lineis subjiciebant. Et in posterioribus haec arcana recondiderant. Vieta etiam adjectis argumentis quaedam [...] demonstravisse visus est. Cartesius de­speratam rem agnovit. Plerique pro­posito Problemati satisfecisse sibi visi sunt, si ad hoc redegissent, ut eo soluto monstrarent aliquod clausorum istius­modi esse reseratum. Te testem invoco, Maxime Archimedes, in secundà se­cundi de Sphaerâ & Cylindro, nisi men­dax imponat memoria, Hinc itaque captandam scriptis meis umbram censui. Tu modo apud temet in consilium se [Page 55] vocatum hoc pensi habeto. Author vel suâ industriâ perfecit quae offert, vel privilegio magnae Providentiae accepit. Si à se & ingeniieâ virtute, quâ plura ejusmodi conficere in parato habeat, certè is est, ut non sint contemnenda illa caetera, quae in publicum usum elaboravit; imo hoc nomine trutinâ acri àigna, quia de tali orta sunt patre. Sin ab exorti [...] vigilantiâ profectum hoc munus suspicaris, expende quanto fortiùs te ad reliquorum examinationem allegatum comperias. Me aspicis? Intuere me hominem, quem nemo Geometram salutet, modo ipse sit. Neque e­nim Geometrices plenitudinem vel ap­petivi. Prelectorem non audivi; studium non sum professus; magnorum Authorum nullum perlegi, non saltem Euclidem. Aliarum Disciplinarum ambitio me semper traxit & defixit: Geometricorum hunc fructum & spera­vi & tuli, ut eorum rigorem ad Meta­physica traducerem. Caeteroqui oblecta­mento mihi erant, cum deforet potiorum commoditas. Talis cum sim, non à me haec habes, sed ab eo, qui ex legibus pro­videntiae suae ea Gubernationi Ecclesiae suae in hoc rerum articulo opportuna & [Page 56] fecit & vidit: Illi accepta refer. Mi­hi si grataris, injuriarum te postulo, quod plus in me oneris aggeras, quam cui sim ferendo: & in Deum, à quo avertis quale quale à te debetur benignitatis praemium. Quod superest, tibi consule, & ostentum a coelo ad te delapsum ne contemnito.

In English thus. A GOLDEN SHIELD: OR, A Geometricall Defence As an APOLOGY for all his other Writings in the ob­scurer Sciences.

As for the Preface, the first part there­of concerns not our present purpose, as speaking onely of the profound re­search made into nature by that wor­thy Gentleman, Sir Kenelme Digby, (whose learning and respects to Mr. White would never certainly have suf­fered this Geometrical Treatise to pass abroad, had he seen it before it was published) I shall onely English the se­cond, which Mr. White falls upon by occasion of an objection that some things touched in Sir Kenelmes Philo­phy seemed not fully agreeable to Sciences of higher consequence. The refutation of which objection Mr. White undertook, and so gives a brief account of such writings as he had pub­lished to that effect: and comes at last to this present Tutela which he is about to publish, intending it as a defence of all he hath hitherto writ­ten, and whereof he speaks to his Rea­der in these words, Tu modo apud te­met, &c. as we saw just now.

In English thus.

TAke gentle Reader this into thy serious consideration, either the [Page 58] Author (meaning himself) hath per­formed the things he here presents thee with, by his own Industry, or by Gods peculiar Providence. If they be the fruits of his own industry, and proceed from that vigour of wit, by which he is also ready to perform ma­ny the like: certainly he is a person whose other writings formerly pub­lished for the common good, ought not to be contemned. Yea, for this very reason, they deserve a profound consideration, as proceeding from such a Father.

But in case thou consider them as coming from the Almighty, then think with thy self; how much great­er thy obligation is to examine the rest of his Works. Lookest thou upon me? Behold the man, whom no man will call a Geometrician if he be one himself. Neither did I ever desire to compleat my self in that faculty; I was never taught it, nor did I ever pro­fess to study it. I never read over any chief Author in that Science, no not so much as Euclide; but was alwayes delighted with other studies. From Geometry I both expected and attain­ed [Page 59] sufficient for transferring its vigo­rous proceedings to the Metaphysick. Otherwise it was onely my recreation when I wanted better employment. Since therefore I am such, thou hast not these things from me, but from him, who in his Divine providence, both saw and fitted them for the Go­vernment of his Church in this pre­sent conjuncture. Give him the thanks; for if thou apply them to me, I shall expostulate the injury done me in laying a greater weight upon me then I am able to bear; and thou wilt lose the reward thou shouldest receive from God. It remains that thou neg­lect not thy own good, nor contemn a wonder come down to thee from Hea­ven.

Thus Mr. White in his Preface. By all which, and by the Title of his Book, he plainly shews, that according to the clearness and solidity of the following Demonstrations in Geometry, men must take the just measure of the solidi­ty and strength of his other Demonstra­tions in Philosophy and Divinity. And thus much for those places of the Pre­face mentioned in the precedent Let­ter. [Page 60] I will now set down those that concern the dispute between Mr. White and Gulden, which are onely two; the former is in Nota secunda before the tenth Proposition: the latter in Nota Quarta at the end of the twelfth.

Ex Tutela Geometrica ante Prop. 10. Nota Secunda.

Finieram, & regulam cum circino consecraturiebam; cum ab amicis mo­nitus sum, quam in Exercitatione Geometrica exhibueram spiralis ad Pe­ripheriam Circuli aequationem, à magni nomin [...] Mathematico, & prius excogi­tatam, & eàdem demonstratione con­firmatam, & posterioribus consiliis re­pudiatam fuisse, & oppositâ demonstra­tione reprobatam. Conscius eram, non indiligentèr apodixi meae invigilavisse. Terruit tamen hominem (cui omnia alia prae Mathess praehabita fuerant) tot no­tis veritatis impressus rumor. Tollo de Tabula manum, & cum typis manda­vissem, quae sunt praemissa, caeter a usque ad examinationem hujus improperii sus­tinenda decrevi.

Author oppositionis erat quidam Pau­lus Guldenus, ex Societate Jesu, editor justi voluminis, quod pro Geometrico suppositum Centrobaryca appellavit. Quid agerem? ubi degebam, opus illud non apparebat, & negotium quod illic gerebam, ad umbilicum perductum erat, & jam egelidum ver monebat aestivam sedem Ciconiarum monitu [...] vestigare. Contuli me itaque Lugdunum Batavo­rum, & gratiâ clariff. Mathematum ibidem Professoris Examinationem Pro­blematis mei aggredior. Primò ipsam revisi; apparuit constantissima: sum­mam tibi sic accenseo, &.

In English thus.

I Had even now ended, and began to lay my Rule and Compass aside, when I was admonished by my friends, that the equation of a Spiral to the circumference of a Circle, which I had demonstrated in my Exercitatione Geo­metrica, had been found out before and confirmed with the same Demonstra­tion, by a famous Mathematician: who afterwards retracted it, and by a contrary Demonstration, shewed it to [Page 62] be false. I was conscious to my self that I had not slightly examined my Demonstration: nevertheless a rumor with so many marks of truth somewhat frighted me, being a man that esteem­ed all other learning before the Ma­thematical. I presently made a stop, and having printed the precedent part de Quadratura, I deferred the rest, till I had examined this reproach.

The retracting Author was one Paul Gulden of the Society of Jesus, who had printed a compleat Volume, which he pretending to be a Geome­tricall Work, called it Centrobaryca, What should I do? Where I then lived. this Book was not to be had, and my work in hand was even now finished. Besides the Spring drawing on, did in­vite me by the crying of the Storks, to seek my Summer habitation. I went therefore to Leyden in Holland, and with the favour of the most famous Professor of Mathematicks there, I be­gin to examine my Probleme; I re­vised it, and found it most solid, Take here the summe thereof, &c.

This is Mr. Whites relation of the beginning of the Dispute between [Page 63] him and Gulden, handsomely, as you see, contrived, that he may not seem to have stollen the said Demonstration out of Gulden, but to have fallen upon it himself, or had it from Heaven. Yet all this will not serve his turn, but still the Reader will imagine those words in his Preface, where (speaking of this Demonstration together with the rest) he sayes, Non haec à me ha­bes, sed ab eo qui ex legibus Providentiae suae, &c. are to be changed thus, (applying them to this particular) Non haec à me habes, sed à Paulo Gul­deno, qui ante trigintaferè annos ea pri­mò invenit, & postea retractavit, &c. After this relation Mr. White proceeds to confirme the said Demonstration and infringe the Retractation of Gul­den, shewing his computation to be false, as he imagines: which done, he makes his Nota Quarta, or invective against Gulden in these words.

Nota Quarta.

Calculus itaque Guldenianus impe­ritas est, & qualem ab ipso acceptari (neque enim vel talem ipse instruxit) [Page 64] decebat, homine prorsus Amathemati­co, ut legenti ipsius scripta pronum est patere. Nam dum proportionem Spi­ralis ad circulum ad struere conare­tur, assumpsit sine probatione proposi­tionem prorsus improbabilem, nempe, lineas intra aliam ductas esse minores illâ. Et si enim videatur de Inscriptis velle loqui, tamen quas ipse scribit ni­hil minus sunt quans Inscriptae, cum circum scriptam non accedant nisi al­tero duntaxat termino. Rursus aequali temeritate vult Arcus circuli esse pro­portionaliter medios inter arcus Spira­lis aequalium angulorum. Sed (quod foedissimum est) tantae vanitatis est, ut cum erravisse sese putaverat, neque delendo tegere, neque candidè con­fiteri sustinuerit, sed excusationes texe­re quasi in ipso errore egregiè se gesserit, ostentare pergat, Quae (utpote de sumptae ex locis Logicis vel Rhetoricis) clarè docent hominem officij Geome­trici (quod hac respust) esse prorsus ig­narum, & ex eo Semidoctorum genere, qui cum ex magnorum virorum scriptis egregia multa depeculati fuerint, ut sua faeciant, additis quibusdam levibus, justi voluminis oftentatione se vulgò [Page 65] discentium ostentant: & (quod perni­ciosissimum est) mixtis incertis, sacrum Scientiae nomen denigrant, ut abundè egit noster Guldenus; Saltitationem telluris circa centrum, & consistentiam Centri in puncto imaginario, in Geo­metricum tractatum inferciens. H [...]c coactus sum de homine caeteroqui ignoto prodere quia umbra Tomi illustris, per opinionem consequam, officiebat veritati, quam ejusdem studiosis offerebam. Quantumvis operae pretium erat lecto­rem monitum redàere de exitiali hâc Sciolorum Sectâ, quae sub professione facultatis garriendi omnem certitudi­nem, tum è Scientiis, tum ex Fide Chri­stianâ tollere molitur.

In English thus.

WHerefore Guldens calculation is unskilful, and such as was fit to be received by him (for he made it not himself But he there made another more ac­curate.) a man no way vers'd in Mathematick, as his Reader will easily perceive. For endeavouring to give the proportion of a Spiral to a Circle, he assumes without proof a proposition wholly improbable, viz. [Page 66] that lines drawn within another line, are less then it. For though he seem to intend to speak of lines inscribed; yet those he describes are nothing less then such, since they touch the circumscri­bed but with one end onely. In like manner with equal temerity he will have the Arches of a Circle to be mean proportionals between the Ar­ches of a Spiral of equal Both these are retra­cted by Gulden, prop. 4. Angles. But that which above all is the most detestable, his vanity is so great, that when he thought he had erred, he could neither endure to suppress it, nor candidly to acknowledge it, but pro­ceeds framing excuses, and brags, as if therein he had carried himself very gallantly. All which, being but flou­rishes of Rhetorick, clearly shew him to be a man wholly ignorant of what belongs to Geometry; which uses no such Arts: and that he is one of those petty Schollars, who having stollen divers excellent things out of other mens Writings, that they may make them seem their own, adde some few trivial matters, and then boast them­selves amongst their Schollars as the Authours of a great Volume: and [Page 67] (which is most pernicious) by ming­ling many uncertainties, defile the Sacred Name of Science; as this Gulden hath done to the full, thrusting into a Geometricall Trea­tise the Dancing of the Earth a­bout its Center, and the Consistency of the same Center in an Imaginary Point. These things I was forced to publish of a man otherwise unknown to me, because the shadow of so fair a Tome, through the opinion it had gain'd, hindered the light of that truth, which I propos'd to those that sought it. Nevertheless it was worth the labour, to admonish the Reader of this pernicious Sect of Sciolists, who under profession of the Faculty of Prating, endeavour to remove all certainty, as well from Sciences, as from Christian Faith.

Hitherto we have heard, or rather seen Mr. Whites gall against this Au­thour, through whose sides he unwor­thily seems to endeavour the wound­ing of his whole Order, under the title of Exitialis Sciolorum Secta. Truly a man would wonder to see, how stu­diously [Page 68] and compleatly Mr. White here acts the part of a malitious Detractor, seeking every way to defame his Ad­versary: for besides what we have al­ready heard in the precedent Letter, he intimates him here to be so little versed in the Mathematicks, as not to be able to make even the computation of a Polygone of twelve sides: for speaking (as we have heard) of such a Calculation which he tearms unkilful, and calls it Guldens, (though he tells us withal, that Gulden made it not himself, but received it from another) he malitiously inserts in a Parenthesis, Neque enim vel talem ipse instruxit, thereby to insinuate, that Gulden was unable to frame so trivial a Computa­tion, as he (Mr. White) esteemed this. Wherein yet he could not be ignorant of the great injury he did this Author; who having set down the said Calcula­tion of twelve sides, acknowledging it to be none of his own, but sent him from another, he examines and ap­proves it in prop. I. c. 3. lib. 2. Which done, he presently in prop. 3. exhibites another of his own far more accurate, as consisting of a thousand sides, and [Page 69] performed by a different way of com­putation, with laborious Tables expres­sing the quantity of each particular side: thence also probably inferring that the proportion of the said Spira [...] to the half Circumference is as 1961 to 1818 proximè. Yet Mr. White would take no notice of this Computa­tion, although it were so near the place from whence he took that other of twelve sides.

But having attained his end in this he proceeds, finding a means to asperse him with a censure of absolute igno­rance in the Mathematicks: where that the Reader may see Mr. Whites mali­tious way of proceeding, he must know that Gulden (as we shall present­ly hear in his own words) having (be­fore the printing or publishing the of­ten mentioned Demonstration of the Spiral) discovered by help of a Friend an errour therein, thought good not­withstanding to print it, not as a true one, but as erroneus. This he per­forms in c. 2. lib. 2. and presently c. 3. shews and refutes all the particular er­rours committed in c. 2. to the end that others advertised of the errours [Page 70] committed in cap. 2. might beware of committing the like; Ʋt sciant (saith he) sibi cavere à scopulis.

Now here Mr. White playes his game, and taking no notice at all of this, playes upon Gulden, as if he had affirmed the contents of cap. 2. to be really true; which, as I said, Gulden did publish as absolutely false: then which a more unworthy proceeding can hardly be imagined, as will now appear.

For in the above named Nota Quar­ta, Mr. White terms him, Hominem prorsus Amathematicum, a man utter­ly ignorant of the Mathematicks, in assuming (as he sayes) without proof a Proposition wholly improbable, viz. that Lines drawn within another are less then it.

But in this Mr. White extreamly wrongs the Authour, who onely sets down cap. 2. Prop. 3. the said Proposi­on as erroneous, which he took at first sight to be true; and afterwards cap. 3. Prop. 1. at large declares the errour. Which had he not done, I dare boldly affirm, that all Mr. Whites Geometry would never have been able to disco­ver. [Page 71] But by this proceeding Mr. White thinks to attain what he aimed at; viz. the depressing of Gulden, and the exalting of himself. For by con­cealing Guldens refutation of the said Proposition, on the one side he would give the world to understand, that Gulden was not able to see and rectifie the errour: on the other he would gain to himself the opinion of a sharp wit, and deep insight into the Princi­ples of Geometry, in being able to detect what so great a Mathematician (as he reports in his Nota secunda that Gulden was esteemed) could not per­ceive: whereas indeed if Gulden had not put it into Mr. Whites head, it had never been there. But to seek the glo­ry of a great Wit and profound Ma­thematician, as also to purchase an esteem to all his other Writings by such Arts as these, is a thing most un­worthy of a Gentleman. And though such Artifices may for a time, by some more affected to him then learned to discover them, be received with ap­plause; yet at last they will be disco­vered, as here they are, and instead of the hoped glory, bring nothing but [Page 72] shame to such as use them.

Lastly, he accuses Gulden of rashness for affirming (as he sayes) the circular Arches to be mean proportionalls be­tween the Spiral Arches of equal An­gles. Wherein he uses the like artifice as before, by making Gulden assert even what he absolutely denies. For this Assertion corresponds onely to what Gulden sayes in the said cap. 2. Prop. 8. where he delivers it as false, and after proves the falsity, cap. 3. prop. 4, n. 6.

Thus much for Mr. VVhites invective against Gulden; let us now, if you please, hear Gulden speak himself, and see whether there appear in his words that great vanity, stubbornness, want of candour, and such ostentation as Mr. VVhite reproaches him with: and thereupon frame a judgement of them both, accordingly. Gulden therefore in the Preface to the cap. 3. gives a full account of his retracting the Demon­stration of the Spirall: which is as followeth.

De Centro Gravitatis, Lib. 2. Cap. 3. Pag. 58.
Examen eorum quae proxime praecedenti capite tradita sunt.

HƲcusque ergo, amice Lector, novae haec, & non minùs jucunda quàm pulchra, de lineis Spiralibus speculatio non tam traxit, quàm tum equis quàm velis suavissimè nos provexit, nullum sive in aequore sive in montibus nobis ti­mentes vel periculum apertum, vel insi­dias latentes. Nam regiâ nos incedere viâ scivimus potiùs, quàm arbitrati su­mus; & solùm intenti fuimus quâ ra­tione, Scopum videlicet nostrum intuendo, nobis paulatim semitam ad indagandum Lineae Spiralis Gravitatis Centrum com­modè praepararemus. Occurrer at saepius quidem, dum haec tractaremus, non levis cogitatio; quae tamen ob certas rationes nos in caepto retardare minimè visa est: nimirum si haec Spiralis Lineae dimensio tam obvia, tam commoda, tamque ordi­nata est, ut nos eam invenimus; tam fa­cilè etiam progreditur, támque firmis [Page 74] potest roborari Demonstrationibus; cur cam non Magnus Archimedes, qui ea, quae alii de Lineâ Spirali proposuerant, ipse admirabili (ut cum Pappo loqua­mur) quâdam aggressione demonstra­vit; cur eam (inquam) Dimensionem libro suo De Spiralibus non inseruit? Sed facilè nobis ipsis responsum dedi­mus: ipsum videlicet Archimedem plu­ra alia, quae tamen alii post ipsum tractâ­runt, velneglexisse, vel studio ac volens praeteriisse; vel etiam jam ab ipso tra­ctata, injuriâ temporum, intercidisse. Quemadmodum etiam fecit, cum ae Pla­norum centro ageret gravitatis: omisit enim Tractatum de centro Linearum. Et sicut nos non absterruit illa objectio ab indagatione Centri Gravitatis Linea­rum, praesertim Circularium; sic & hìc nobis ipsis fecimus animos novi aliquid circa Spirales inveniendi, quod vel ipsum Archimedem fugere, aut posteros nos la­tere potuerit.

Et nostro quidem judicio rem tunc fe­licitèr & incepimus, & in eâdem ma­gnis etiam itineribus perreximus. Sed ecce dum hoc loco in medio quasi essemus cursu, portumque etsi valdè procul ad­huc positum, jam à longè tamen jam jam [Page 75] conspiceremus, vela repentè & erant contrahenda, & securitatis causâ ad le­genda littora prora convertenda. Incidi enim tunc primùm in Examen quoddam, per numeros institutum, dimensionis Li­neae Spiralis; de quo antè quidem inau­diveram, sed qualitèr ant quâ ratione dimensio illa progrederetur, cum rectâne, an cum curvâ, aut purè circulari, Spi­ralis illa linea conferretur, omninò nesci­ebam: tantum abest, ut ips [...] justam proportionem, à nobis inventam, inde redargui posse suspicarer. Quare ex pri­mo illius aspectu nequaquam sum ter­ritus; quippe qui meis fidebam Demon­strationibus, tam Geometricis quam Arithmeticis, quas irreprehensibiles esse judicavi. Hostem tamen qualem qua­lem saepe audivi spernendum esse minimè: quippe qui, quando minimè putamus, vel obesse vel nocere possit.

Examinavi igitur examen illud; quo in labore mille potius sperabam me in­venturum in calculo hujus examinis er­rores, quàm vel unicum in meis in­ventis. Sed contra quasi accidit. Re­peri enim Lineam Spiralem primae Cir­culationis majorem esse Semiperipheriâ primi Circuli; & tacitè victusque ma­nus [Page 76] dare debui. Quid facerem? Dissimu­laremne? Tacerem? Mordicus mea, instar Circuli Quadratorum suprà no­minatorum, defenderem? Et Archime­dem ipsum Euclidemque in jus vocarem, accusarem, condemnarem? Nequaquam. Sed servandum mihi duxi id, quod ipse Jos. Scaliger sibimet quidem servandum praescripsit; at minime servavit. Sic enim in Appendice ad sua Cyclometrica habet. ‘Primum, aio, in omnibus Scientiis & Artibus posse saepe tolerabilitèr pecca­ri: in Mathematicis ne semel quidem debere. Nam ut ait quidam vetus Scriptor, [...] Ita (que) cum Mathematicus erro­rem suum deprehenderit, primus occu­pare debet Me, Me, adsum, qui feci. Postquam autem per alium id cogno­verit, si non statim Castigatori gra­tias agit, malè de homine; si non corri­git, malè de Mathemetica meritus est.’ Verum bonus ille Scaliger praecipuos erro­res suos, atro & rubro colore jam edi­tos, non solum non correxit; sed & majori inscitiâ animique tumore pertina­citèr defendit. Conclusi ergo, in meis inventis alicubi peccatum esse. At ubi [Page 77] lateret anguis in herbâ, non it a facilè ne­que statim videre aut judicare potui. Quare Scripta mea amico in Mathema­ticis benè docto dedi perlegenda, ut an ea sibi constarent animum diligentèr ad­verteret, suumque mihi de iis judicium candidè aperiret, eundem rogavi.

Verùm enim verò dum ille differret lectitandi operam, ipse errorem meum re­peri, & digito (quod aiunt) demonstrare potui. In eo solùm haesi, an totum illud Caput praecedens, cum principi meo in­tento ac fini nihil tolleret; parum, etiamsi omnia vera essent, adferret, omittendum esset, totumque negotium mensurationis Lineae Spiralis dissimulandum: an vero, prout jam scripta essent omnia, unà cum hoc Examine edenda. Occurrebant ra­tiones plures & variae, prò & contrà: Vicerunt tamen illae, quae in bonum alio­rum laborem horum, partem saltem ali­quam, ipsis communicandum esse, caeteris praelatae sunt, suasêrunt & persuaserunt. Praesertim cum non defint exempla Au­ctorum, qui & cum laude suâ & cum utilitate Lectorum idem factitârunt: qui si nullum alium hinc auferrent fru­ctum, is saltem satis esse posset, quod in­veniant cautionem, ut si curiosiùs sive [Page 78] de Spiralibus, sive de alijs inquirere ve­lint, sibi sciant cavere & à scopulis, & ab alijs incommodis, in quae facillimè in­currere possent. Geometria profectò ipsa, secundum judicium Josephi Scaligeri suprà cap. primo Propos. 4. num. 7. adductum, sibi inprimis gratulabitur, quòd accessione saltem novorum aliquot Epichirematum locupletata sit.

Primum igitur indicandum est, qua­liter in cognitionem venimus inventa nostra lubricae esse fidei; deinde, vbinam haereat error, ostendendum: tum singulae propositiones examinandae, & pro meritis approbandae vel reprobandae, & siquidem id fieri commodè poterit, erroneae corri­gendae. Omisimus autem plurima jam conscripta, bonoque ordine ac methodo di­gesta; quae si rationibus suis solidè nixa fuissent, Lectori plurimùm oblectationi esse potuissent: cum verò vacillantia ea inventa fuerint, ne fastidio potius essent, jure meritò ea praeterivimus. Non esset autem abs re cogitationem suscipere, qua­lisnam aut quae sit illa flexuosa linea, & quâ arte illa compendiose describi possit, quae illas haberet proprietates, quas frustrà Spirali attribuimus. Id quod in aliud tempus, vel potius aliis faciendum reservamus.

Propositio prima. Occasionem Examinis hujus ac Dubitationis pressius declarare.

FƲisse quendam, qui Dimensionem Lineae Spiralis ante nos instituerit, memini me aliquando audivisse ex P. Hieronymo Kinig Societatis nostrae Mathematico, & olim in Ingolsta­dianâ, Dilinganâ, ac Pragensi Aca­demiis earundem Mathematicarum Disciplinarum Professore accuratissimo, mihi & Romae & alibi notissimo; imò eundem Lineam illam alicui alteri aequalem, sine tamen ullâ Demonstra­tione, pronunciasse; quod assertum di­ctus ille Professor examinaverit: cui vero Lineae illam adaequaverit, non so­lùm tunc scire, verum an aliquando id sciverim planè meminisse non potni. Cum ergo versarer in scriptione supe­rioris Capitis, venit in mentem Examen illud quod diximus, recordatione tamen satis confusâ. Existens ergo Graecii in Stiriâ scribo Viennam, ubi Mathe­maticus [Page 80] ille manebat; & siquid habe­ret his de rebus in Scripto, ad me mit­teret rogavi: non quòd incertus essem de meis jam inventis & scriptis, aut ullo modo de iisdem dubitarem, sed ut illud ipsum cum meis conferrem. An­nuit ipse, & sequens ad me misit, sive Examen, sive contra Asserta instan­tiam & reprobationem: quam cum examinassem, ut suprà diximus, eam veritati consonam esse, manifestè de­prehendi. Sic autem se habebant illa.

2. Propositum sit demonstrare, Li­neam Spiralem majorem esse Semi­circumferentiâ; Intellige Circuli pri­mieam comprehendentis.

The same in English. [Page 81] OF The Center of Gravity. Lib. 2. Cap. 3. Pag. 58.

THus far (Courteous Reader) had this new, and no less specious then delightful speculation on the subject of Spiral Lines rather swiftly advanced me, by Sea and Land as I may say, then slowly drawn me, who apprehended nothing either of appa­rent danger, or unexpected surprize. For indeed I rather knew, then ima­gin [...]d, that I travelled in the High Road; and looking stedfastly on my main design, I was wholly attentive to the means whereby to tread out a commodious Path for the Discovery of the Center of Gravity in the Spiral. True it is, while I was plodding there­on, a serious reflection came often into my minde, which yet, for certain rea­sons, was not sufficient to retard my course, viz. That if this Dimension of the Spiral Line were so obvious, easie, and commodious a thing, as I found it [Page 82] to be; as also strengthned with such firm Demonstrations, how came it to pass that the great Archimedes, who (to speak with Pappus) did with admi­rable Dexterity demonstrate those Proprieties of the Spiral Line, which other men had onely hinted at; how came it, I say, to pass that he did not insert this Dimension into his Book of Spirals? But I easily answered my self; to wit, that Archimedes had ei­ther neglected or purposely omitted many other things, which have since his time been treated by others; or else it must be, that what he wrote thereof, hath perished by the injury of time. The like he did when he treated of the Center of Gravity in Plains; for he omitted the Tract of the Center of Lines. And as that objection deter­red me not from enquiring the Center of Gravity in Lines, especially Circular ones, so here I encouraged my self in hope to discover something new con­cerning Spirals, which hitherto had escaped both Archimedes and all that had come after him.

And truly in my opinion I began the business happily enough, and had [Page 83] made a great progress therein; but on a sudden when I was half way on my Voyage, and came within Kenning of the Port, I was fain to strike Sail, and for security, to make directly towards the shore: for I then first lighted on a certain Examen of the Dimension of the Spiral Line, performed by numbers: whereof indeed, I had heard before, but could not tell how or which way that Dimension pro­ceeded: or whether that Spiral were to be compared with a right Line or crooked, or a pure Circular Line. So far was I from suspecting, that the ex­act proportion I had already discover­ed, could be disproved thereby. So that I was nothing at all troubled at the first sight of this Examen, as being very confident of my own Demon­strations, both Geometrical and Arith­metical, which I thought to be irrepre­hensible. Yet I had often heard, that an enemy, how mean soever he seems, ought not to be contemned; for when we lest think of him, he may hap to stand in our way, if not do us a mis­chief.

I took in hand therefore to examine [Page 84] that Examen, promising my self to discover a thousand errours in his Cal­culation, rather then one in my own Inventions. But it happened far otherwise; for I found that the Spiral Line of the first Revolution was great­er then the Semi-circumference of the first Circle: so that I saw I was fairly to submit. See how unjustly Mr. White charges this Au­thor of obstinacy, for not confessing his errour. For what should I do? Should I dissemble the matter? should I hold my peace and conceal it? Or should I, with those Squarers of the Circle above-mentioned, obstinately defend my own Assertion, though I knew it to be false? Should I dare to question, accuse, yea and condemn Archimedes and Euclide himself, to maintain my own opinion? By no means. I resolved therefore to observe the Rule, which Joseph Scaliger once prescribed to himself, but never ob­served. It is in the Appendix to his Cyclometriques; where he thus speaks. I grant, saith he, that in all other Arts and Sciences, errour may be tollerably committed oftentimes: but in the Mathematiques it ought not so much as once. For as an old Wri­ter saith, [...], &c. All things digested [Page 85] by Art ought to have an unreprove­able evidence. So that a Mathe­matician observing his own errour, ought before all others to cry out, 'Tis I, 'tis I, here I am that did it. But if he comes to know it by means of some other person, unless he presently gives thanks to his Cor­rectour, he is ill-deserving towards the man; but if he do not presently amend his errour, he wrongs the Science it self.’ Yet this honest Sca­liger was so far from correcting his own over-sights, published both in black and red, that with greater igno­rance and animosity he still obstinately defended them. I concluded therefore with my self, that something was amiss in my Deductions. But where this Snake (the errour) lay, I could neither so easily nor so presently perceive. Wherefore I gave these my Writings to a Friend well skilled in the Mathe­maticks to read them over; entreating him to consider as attentively as he could, whether they were consistent or not; and that he would impart his judgement of them to me with all candour and clearness.

But to tell you the plain truth, while my Friend deferred somewhat the pains of reading my Writings, I in the mean time discovered the errour my self, and was able (as the Proverb saith) to point it out with my finger. Onely I could not well resolve, whe­ther I should now wholly lay aside the foregoing Chapter, (seeing that to do so would not be any prejudice to my principal intent, as on the other side it would not have added much to it, though every thing therein had proved true) and so dissemble the whole matter concering the measu­ring of the Spiral Line; or other­wise should publish whatsoever I had written on that Subject, toge­ther with this Examen. Many and various Reasons occurred to me Pro and Con: but at last those prevailed, which for the See if this Au­thors not expunging his errour proceeded out of pride, as he is accu­sed. good of others incli­ned me to think that some part at least even of those my Labours, was not to be denied to the publick. Especially seeing there wanted not the examples of Authours, who to their own praise, and the benefit of their Readers have done the like; who though they should [Page 87] happen to reap no other profit by it, yet were this alone sufficient, that they have here a Caveat given them, that in case they should themselves desire to search more curiously into this Subject of Spiral Lines, or any other of like nature, they should proceed warily and advisedly in the Where is now that great vani­ty Master White would pin upon this Authour?business, for the avoiding of those rocks of in­conveniences and errour, which other­wise they will most easily run upon. And lastly, that Geometry it self, even according to the judgement of the same Joseph Scaliger, (cap. 1. prop. 4. num. 7.) should rejoyce, being enriched thereby with the Addition of some New Endeavours.

The first thing therefore here to be done is to declare, how I came to know that my Inventions were but doubtful and uncertain; next to shew where the errour lyes: and lastly to examine all the severall Propositions, with approbation or rejection of them according to their merits; yea (where it may conveniently be done) by rectifying and correcting those which are erroneous. Yet many things I have omitted, though already written, [Page 88] and digested by me into due order and method; which had they been built upon good and solid grounds, would have given great delight to the Rea­der. But finding them loose and slip­pery, (to avoid offence) I have justly laid them aside. However, it might (perhaps) be matter not unworthy our consideration, to think what man­ner of Bending Line that is, (and also how it may be compendiously drawn, and described) which might be found to have all those properties, which in the Spiral Line we have hitherto but vainly sought. But that's a thing I must defer to some other time, or ra­ther leave to other persons to per­form.

The First Proposition. More particularly to declare the occasion of this following Exa­men, and of Doubting.

THat there was one, who before me had attempted the measu­ring of the Spiral Line, I remember well to have heard long since from the mouth of Father Hierome Kinig, a [Page 89] Mathematician of our Society, and formerly a most accurate professour of those Sciences in the Universities of Ingolstad, Dilingen, and Prague; whom I knew very well both at Rome and elsewhere; yea, that the abovesaid person had affirmed (but without any Demonstration given) that the said Spiral Line was exactly equal to some other Line: which Assertion of his the said professor did also examine. But to what Line he made the Spiral to be equal, I cannot possibly call to minde, whether I did either then, or any other time know it in all my life. Whilest therefore I was writing the precedent Chapter, I hapned to think on the afore mentioned Examen; yet remembring it but confusedly, and in gross. Whereupon being at Gratz in Stiria, I wrote to Vienna where the said Mathematician then was, and en­treated him, that if he had any thing of this Subject, he would send it in writing to me; not that I was then any way jealous of my self, or did in the least measure doubt of my own writings and discoveries; but onely that I might communicate what I had [Page 90] written, with those of my own pro­fession. He forthwith yielded to my request, and sent me this following Ex­amen, or rather refutation of the things I had asserted; which having my self examined, (as I said before) I manifestly found it agreeable to truth. Now that which he wrote was as followeth.

2. The second Proposition may be to shew, that the Spiral Line is greater then the Semi circumference to wit, the Semi-circumference of the first Circle that contains it.

Though I had here ended my ad­ditional Vindication of a worthy Ma­thematician by the name of Gulden, because I found him so written by the Author of the precedent Letter, as following Mr. White, who names him Paulus Guldenus; yet I thought it not amiss to advertise the Reader be­fore I took Pen from Paper, that his Adversary could not be ignorant that he calls himself Paulus Guldinus in his own printed works, not Guldenus. Whereby one may probably conje­cture, that this was a meer affected mi­stake [Page 91] in Mr. White, to confirm his Reader in the belief of that incredible story he delivers, that he had never ei­ther seen, nor heard of this Authors Work, till his own was ready for the Press.

FINIS.

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