<?xml version="1.0" encoding="UTF-8"?> <TEI xmlns="http://www.tei-c.org/ns/1.0" xml:id="NATP00013"> <teiHeader> <fileDesc> <titleStmt> <title>Mr Newtons Letter of April 13. 1672 … being an Answer to the fore-going Letter of P. Pardies</title> <title type="short">First reply to Ignace Pardies</title> <author xml:id="in"><persName ref="nameid_1" xml:base="http://www.newtonproject.sussex.ac.uk/catalogue/xml/persNames.xml" ><forename>Isaac</forename> <surname>Newton</surname></persName></author> </titleStmt> <extent><hi rend="italic">c.</hi> <num n="word_count" value="956">956</num> words</extent> <publicationStmt> <authority>Newton Project</authority> <pubPlace>London</pubPlace> <date>2007-03-17</date> <publisher>Newton Project, University of Sussex</publisher> <availability n="lic-text" status="restricted"> <licence target="http://creativecommons.org/licenses/by-nc-nd/3.0/"><p>This text is licensed under a <ref target="http://creativecommons.org/licenses/by-nc-nd/3.0/">Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License</ref>.</p></licence> </availability> </publicationStmt> <notesStmt> <note n="pages">3pp.</note> <note n="language"> <p>in Latin</p> </note> <note n="related_texts"> <linkGrp n="document_relations" xml:base="http://www.newtonproject.sussex.ac.uk/view/normalized/"> <ptr type="is_responded_by" target="NATP00015"/> <ptr type="is_response_to" target="NATP00012"/> <ptr type="is_version_of" target="NATP00310"/> </linkGrp> </note> </notesStmt> <sourceDesc> <biblStruct> <analytic> <author><persName ref="nameid_1" xml:base="http://www.newtonproject.sussex.ac.uk/catalogue/xml/persNames.xml" ><forename>Isaac</forename> <surname>Newton</surname></persName></author> <title>Mr Newtons Letter of April 13. 1672 … being an Answer to the fore-going Letter of P. Pardies</title> </analytic> <monogr> <title level="j">Philosophical Transactions of the Royal Society</title> <title level="j" type="short">Philosophical Transactions</title> <imprint> <pubPlace>London</pubPlace> <date>17 June 1672</date> <biblScope type="no">84</biblScope> <biblScope type="pp">4091-4093</biblScope> </imprint> </monogr> </biblStruct> </sourceDesc> </fileDesc> <profileDesc> <creation> <origDate when="1672-06-17">13 April 1672 (published 17 June 1672)</origDate> <origPlace>England</origPlace> </creation> <langUsage> <language ident="eng">English</language> <language ident="lat">Latin</language> </langUsage> <handNotes> <handNote xml:id="printer" scribe="print">Print</handNote> </handNotes> </profileDesc> <encodingDesc> <classDecl> <taxonomy> <category> <catDesc n="Science">Science</catDesc> <category> <catDesc n="Optics">Optics</catDesc> <category> <catDesc n="Correspondence">Correspondence</catDesc> </category> </category> </category> </taxonomy> </classDecl> </encodingDesc> <revisionDesc> <change when="2001-01-01" type="metadata">Catalogue information compiled by Rob Iliffe, Peter Spargo & John Young</change> <change when="2003-01-21">Tagged transcription by <name xml:id="lc">Linda Cross</name></change> <change when="2003-08-21" status="released">Checked against original by <name xml:id="rhiggitt">Rebekah Higgitt</name></change> <change when="2007-03-01">Coding converted to modified TEI DTD and proofed by <name xml:id="mjh">Michael Hawkins</name></change> <change when="2009-04-20">Updated to Newton V3.0 (TEI P5 Schema) by <name>Michael Hawkins</name></change> <change when="2011-09-29" type="metadata">Catalogue exported to teiHeader by <name>Michael Hawkins</name></change> </revisionDesc> </teiHeader> <text> <body> <pb xml:id="p4091" n="4091"/> <fw type="pag" place="top-right">(4091)</fw> <div> <head><foreign xml:lang="eng">Mr. <hi rend="italic">Newtons</hi> Letter of <hi rend="italic">April</hi> 13. 1672. st. v. written to the Publisher, being an Answer to the fore-going Letter of <hi rend="italic">P. Pardies</hi></foreign>.</head> <p rend="indent0"><hi rend="dropCap">A</hi><hi rend="italic">Ccepi Observationes Reverendi Patris</hi> Ignatii Pardies <hi rend="italic">in <lb/>Epistolam meam de Lucis Refractionibus & Coloribus ad <lb/>Te conscriptam: quo nomine me illi valde devinctum agnosco; atque <lb/>hoc difficultatibus, quas proposuit, cluendis rescribo. Imprimis ait, <lb/>longitudinem solaris Imaginis à refractione Prismatis effectam non <lb/>aliâ indigere causâ, quàm diversâ radiorum ab oppositis partibus so<lb type="hyphenated"/>laris disci profluentium incidentiâ, adeoque non probare diversam <lb/>refrangibilitatem diversorum radiorum. Et, quò assertionis ejus ve<lb type="hyphenated" />ritatem confirmet, ostendit casum, in quo ex</hi> diversa <hi rend="italic">incidentia</hi> 30 <lb/><hi rend="italic">minutorum, differentia refractionis potest esse</hi> 2 <hi rend="italic">grad</hi>. 23. <hi rend="italic">min. vel <lb/>etiam paulo major, prout exigit meum experimentum. Sed hallu<lb/>sinatus est R. P. Nam refractiones à diversa parte Prismatis quan<lb type="hyphenated"/>tum potest inæquales statuit, cùm tamen ego tum in experimentis, <lb/>tum in calculo de experimentis istis inito, æquales adhibuerim, ut in <lb/>Epistola præfata videre est. Sit ergo A B C Prismatis sectio ad <lb/>axem ejus perpendicularis, F L & K G radii duo in x (medio fo<lb type="hyphenated"/>raminis) decussantes & in Prisma illud incidentes ad G & L; <lb/>sintque eorum refracti G H & L m, ac denuò H I & m n. Et <lb/><figure rend="blockCentered"> <graphic url="NATP00013-1.png"/> <figDesc/> </figure> cùm refractiones ad latus A C æquales esse refractionibus ad latus B C <lb/>quam proximè supposuerim; Si A C & B C statuantur æqualia, simi<lb type="hyphenated"/>lis erit radiorum G H & L m ad A B basin Prismatis inclinatio; <lb/>adeoque ang. C L m=ang. C H G & ang. C m L=ang. C G H. <lb/>Quare etiam refractiones in G & m æquales erunt, ut & in L & H;</hi> <fw type="catch" place="bottom-right">atque</fw><pb xml:id="p4092" n="4092"/><fw type="pag" place="top-right">(4092)</fw> <hi rend="italic">atque adeò ang. K G A=ang. n m B, & ang. F L A=ang. B H I; & <lb/>proinde refractorum H I & m n eadem erit ad invicem inclinatio ac <lb/>est incidentium radiorum F L & K G. Sit ergo angulus F x K</hi> 30 <hi rend="italic">min. <lb/>æqualis nempe solari diametro, & erit angulus, quem H I & m n <lb/>comprehendunt, etiam</hi> 30 <hi rend="italic">min. si modò radii F L & K G æqualiter re<lb type="hyphenated"/>frangibiles statuantur. At mihi experienti prodiit angulus ille circiter</hi> <lb/>2 <hi rend="italic">grad</hi>. 49. <hi rend="italic">min. quem radius H I, extremum violaceum colorem, & <lb/>m n, cæruleum exhibens, constituêre; ac proinde radios illos diversi<lb type="hyphenated"/>modè refrangibiles esse, sive refractiones secundùm disparem sinuum <lb/>incidentiæ & refractionis rationem peragi necessariò concedendum est.</hi></p> <p><hi rend="italic">Addit præterea R. P. quòd non sufficit ad obeundum ritè calculum, <lb/>ex longitudine imaginis impactæ in Chartam subtrahere magnitudinem <lb/>foraminis fenestræ; quandoquidem etiam posito foramine indivisibili, <lb/>adhuc fieret aliud veluti foramen latum in posteriori superficie prisma<lb type="hyphenated"/>tis. Mihi tamen videtur, his non obstantibus, quòd refractiones ra<lb type="hyphenated"/>diorum, in anteriori æquè ac in posteriori superficie Prismatis decussan<lb type="hyphenated" />tium, ex adhibitis principiis possint ritè computari. Sed si res secùs <lb/>esset, latitudo hiatûs in posteriori superficie quod ad instar forami<lb type="hyphenated"/>nis est, haud efficeret errorem duorum minutorum secundorum; & in <lb/>rebus practicis non operæ pretium duco ad minutias istas attendere.</hi></p> <p><hi rend="italic">Illi insuper experimento, quod</hi> Crucis <hi rend="italic" >vocaveram, nihil advesa<lb type="hyphenated"/>tur R. P, dum contendit, inæquales radiorum, diversis coloribus im<lb type="hyphenated"/>butorum, refractiones ex inæqualibus incidentiis effectas fuisse. Nam <lb/>radiis per duo admodum parva, ab invicem distantia & immota fo<lb type="hyphenated" />ramina, transeuntibus, incidentiæ illæ, prout ego experimentum insti<lb type="hyphenated"/>tui, omninò æquales erant, & tamen refractiones liquidò inæquales. <lb/>Sin ille de experimentis nostris dubitet, oro, ut radiorum diversis co<lb type="hyphenated"/>loribus præditorum refractiones ex incidentiis paribus mensuret, & <lb/>sentiet inæquales esse. Si modus ille, quem ego ad hoc negotium ad<lb type="hyphenated"/>hibui, minùs placeat (quo tamen nullus potest esse luculentior,) facile <lb/>est alios excogitare; sicut & alios ipse haud paucos cum fructu ex<lb type="hyphenated"/>pertus sum.</hi></p> <p><hi rend="italic">Contra Theoriam de</hi> Coloribus <hi rend="italic">obijcitur, quòd pulveres diverso<lb type="hyphenated"/>rum colorum permisti non candidum sed subobscurum & fulcum colorem <lb/>exhibent. Mihi verò albus, niger, & omnes intermedii fusci, qui ab <lb/>albo & nigro permistis componi possunt, non specie coloris sed quanti<lb type="hyphenated"/>tate lucis tantùm differre videntur. Et cùm in mistione pigmentorum, <lb/>singula corpuscula non nisi proprium colorem reflectant, adeoq; maxima</hi> <fw type="catch" place="bottom-right"><hi rend="italic">pars</hi></fw><pb xml:id="p4093" n="4093"/><fw type="pag" place="top-right">(4093)</fw> <hi rend="italic">pars lucis incidentis supprimatur & retineatur; lux reflexa subobscu<lb type="hyphenated"/>ra evadet, & quasi cum tenebris permista, adeò ut non intensum alborem, <lb/>sed qualem nigredinis permistio conficit, hoc est fuscum, exhibere debeat.</hi></p> <p><hi rend="italic">Obijcitur deinde, quòd à liquoribus quibuscunque diversi coloris in <lb/>eodem vase commistis, æquè ac in diversis vasis contentis, opacitas oriri <lb/>debet; quod tamen, ait, verum non esse. Sed non video consequen<lb type="hyphenated"/>tiam. Nam plurimi liquores agunt in se invicem, & novam sibi mu<lb type="hyphenated"/>tuò partium contexturam secretò inducunt; unde opaci, diaphani, vel <lb/>variis coloribus, ex coloribus permistorum nullo medo oriundis, prædi<lb type="hyphenated"/>ti evadere possunt. Et hâc de causâ experimenta hujusmodi minùs <lb/>apta semper existimavi, à quibus conclusiones deduci possint. Subnoto <lb/>tamen, quòd ad hoc experimentum requiruntur liquores saturis & in<lb type="hyphenated"/>tensis coloribus præditi, qui perpaucos nisi proprii coloris radios trans<lb type="hyphenated"/>mittant; quales rarò occurrunt, ut videbitur illuminando liquores <lb/>cum diversis coloribus Prismaticis in obscurato cubiculo. Nam pauci <lb/>reperientur, qui in propriis coloribus satis diaphani appareant, inque <lb/>alienis opaci. Convenit præterea, ut adhibiti colores sint inter se op<lb type="hyphenated"/>positi, quales existimo fore rubrum & cæruleum, vel flavum & vio<lb type="hyphenated"/>laceum, vel etiam viridem & purpureum illum qui coccineo affinis est. <lb/>Et ex hujusmodi liquoribus nonnulli (quorum partes tingentes non con<lb type="hyphenated"/>gredientur) fortaße permisti evadent opaciores. Sed de eventu nihil <lb/>sum sollicitus</hi>, tum <hi rend="italic">quod luculentius est experimentum in liquoribus <lb/>seorsim existentibus</hi>, tum <hi rend="italic">quod experimentum illud (sicut & Iridis, <lb/>Tincturæ Nephriticæ, & aliorum corporum naturalium phænomena) <lb/>non ad probandam sed ad illustrandam tantùm doctrinam proposui.</hi></p> <p><hi rend="italic">Quod R. P. Theoriam nostram</hi> Hypothesin <hi rend="italic" >vocat, amicè habeo, <lb/>siquidem ipsi nondum constet. Sed alio tamen consilio proposueram, & <lb/>nihil aliud continere videtur quàm</hi> proprietates quasdam Lucis, <lb/><hi rend="italic">quas jam inventas probare haud difficile existimo, & quas si non veras <lb/>esse cognoscerem, pro futili & inani speculatione mallem repudiare, <lb/>quàm pro mea Hypothesi agnoscere. Quid verò censeri mereatur, ex <lb/>responsionibus ad animadversiones Domini</hi> N. N. fortasse statim pro<lb type="hyphenated" />dituris <hi rend="italic">clariùs patebit: <space dim="horizontal" extent="2" unit="characters"/>Interea vale, & perge amare</hi></p> <p><space dim="vertical" extent="1" unit="lines"/><space dim="horizontal" extent="37" unit="characters"/><hi rend="italic">Tibi devinctissimum</hi></p> <p><space dim="vertical" extent="1" unit="lines"/><space dim="horizontal" extent="54" unit="characters"/><choice> <sic>J</sic> <corr>I</corr> </choice> Newton</p> </div> </body> </text> </TEI>
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