| Abstract (croatian) | Konačnom redakcijom svoje optičke rasprave De radiis visus et lucis in vitris perspectivis et iride tractatus krajem 1609. i početkom 1610. godine Marko Antun de Dominis uključio se u prijepor o dalekozoru, neovisno od Galileia, a prije Keplera i Claviusa, usmjeren isključivo na teoriju instrumenta. Kako je zaključeno na temelju pomnog proučavanja posvete urednika Giovannija Bartolija uz pomoć isusovačkih vrela, rane de Dominisove bilješke iz optike nastale su u razdoblju 1588–1595, kad je mladi isusovac bio predavač matematike u Collegium Patavinum u Padovi i profesor matematike i filozofije u Collegium Brixiense u Brescii. A budući da je Bartoli te rane spise okarakterizirao dvojako, kao bilješke (commentaria) i raspravu (tractatus), ostavio nam je dvojbu o njihovoj naravi.
Ciljajući na svoj prinos teoriji dalekozora, de Dominis je poglavlje o dalekozoru završio izjavom: »prvi sam probio led«. S pravom, jer je njegov rukopis De radiis odobren za tisak 27. siječnja 1610, 32 dana prije znamenitoga Galileieva astronomskog izvješća Sidereus nuncius. Predajući rukopis na cenzuru, de Dominis nije znao da se istodobno Galilei u svom spisu usredotočio na primjenu dalekozora u astronomskim motrenjima, a ne na teoriju i konstrukciju instrumenta. Premda je de Dominisov De radiis objavljen najranije u listopadu 1611, više od godinu i pol dana nakon Galileieva djelca Sidereus nuncius, tekstualna analiza početnih stranica Galileieva pionirskog rada i dvaju de Dominisovih neizravnih prigovora Galileiu upućuje na zaključak da de Dominis rukopis svoje rasprave nije mijenjao nakon što je objavljen Galileiev Sidereus nuncius. Zato de Dominisove metode i zaključke u De radiis valja prosuđivati prema stanju istraživanja na kraju 1609.
Ako je Galileiev javni nastup s dalekozorom 1609. i bio povodom za konačno priređivanje i objavljivanje de Dominisove rasprave, ona je očuvala strukturu de Dominisova pristupa optičkim pitanjima iz njegovih profesorskih dana (1588–1595): temelji geometrijske i fizikalne optike, sažeta teorija optičkih leća,tumačenje duge. Najkasnije početkom 1610. izlaganju o lećama pridodan je kratak a dragocjen prinos teoriji dalekozora, prvi koji je sastavljen nakon 25. kolovoza 1609.
U prvom dijelu svoje rasprave pokušao je de Dominis nanizati sve fizikalne i matematičke pretpostavke i poučke na koje će se pozvati tijekom optičkih istraživanja. U svojoj je nakani tek djelomice uspio. Neke su njegove tvrdnje bile točne, neke netočne, a neke nejasne s točno opisanim učincima. Neke je pak naknadno uveo, ondje gdje su mu zatrebale u dokazu. Slično se dogodilo i s temeljnim pojmovima. Primjerice, definirao je pojam vidnog kuta, ali ne i žarišne daljine.
Nakon nejasnog vlastita tumačenja kako nastaje vid de Dominis se u drugom dijelu rasprave vješto bavio optičkim lećama, iako je oskudno poznavao temeljne optičke veličine; primjerice, pojam žarišne daljine i žarišta shvatio je tijekom pokusa. Štoviše, pri izricanju zaključaka o lećama oslonio se isključivo na pokuse. Dva poglavlja o dalekozoru niti je zamislio niti ostvario kao tekst koji će se zalagati za ili protiv Galileia i po tomu je de Dominisova rasprava sebi priskrbila povlašten položaj, neuočen u povijesnim i filozofskim proučavanjima Galileieve epohe. Premda je napisao teorijski tekst o dalekozoru i u prilog dalekozoru, znameniti je Rabljanin dvojio o tomu koliko se instrument može usavršiti, i to s obzirom na njegov glavni učinak – povečanje predmeta. Time je proturiječio jednoj od osnovnih nakana svoga rukopisa – »čudesnim učincima« (effectus mirabiles) lećā!
Da bi protumačio dugu, u trećem je dijelu rasprave de Dominis odabrao tri pristupa: povijesni prikaz tumačenja duge od Aristotela do renesansnih prirodnih filozofa, komentar treće knjige Aristotelove Meteorologije i izvornu znanstvenu raspravu (nova et propria disputatio) temeljenu na vlastitim pokusima i obrazloženjima. Slijedeći Aristotelovo polazište »Odbijanje je uzrok duge.« ponudio je vlastita tumačenja o nastanku unutrašnje i vanjske duge. U njima je izvorni doprinos bio popračen ponekom nejasnočom u obrazloženju i manjkavostima u likovnom prikazu pokusa. De Dominisovo je tumačenje duge bilo nepotpuno upravo ondje gdje se to najmanje moglo očekivati: on nije dosljedno primijenio stavak o lomu svjetlosti pri prijelazu iz jednog u drugo prozirno sredstvo, premda ga je jasno izrekao na početku rasprave. K tomu, opisujući pokuse sa staklenom kuglicom ispunjenom vodom nije razlučio hod pojedinačne zrake i prikaz snopa svjetlosnih zraka. Ta je trajna de Dominisova dilema, pratiti u pokusu jednu zraku ili njihov snop, učinila nerazgovijetnim i njegovo teorijsko obrazloženje i likovni prikaz ključnoga pokusa.
Na stranicama svoje optičke rasprave prirodni filozof i prirodoznanstvenik de Dominis povezivao je teoriju i eksperiment, i to češće nego što su mu mnogi proučavatelji njegova djela bili spremni priznati. Ponekad je vjernost eksperimentalnom nalazu utrla put pogrešnom teorijskom zaključku, a ponekad je vjernost teorijskom polazištu otežavala točno tumačenje pokusa. U de Dominisovim optičkim istraživanjima uzajamne odnose teorije i eksperimenta pratila je stalna napetost s nesigurnim ishodom. |
| Abstract (english) | The final version of de Dominis’s optical treatise De radiis visus et lucis in vitris perspectivis et iride tractatus, completed by the end of 1609 and the beginning of 1610, was marked by his contribution to the controversy on the telescope independently of Galileo and prior to Kepler and Clavius, devoted entirely to the theory of instrument. Close study of the dedication written by Giovanni Bartoli, the editor, and the Jesuit archival sources shows that de Dominis’s early writings on optics date from the period when the young Jesuit lectured mathematics at Collegium Patavinum in Padua (1588–1590) and was professor of mathematics and philosophy at Collegium Brixiense in Brescia (1592–1595). Bartoli’s dual characterization of these early writings, referred to as notes (commentaria) or treatise (tractatus), leaves us with a dilemma concerning their nature.
Alluding to his contribution to the theory of the telescope, de Dominis concluded the chapter on the new scientific instrument with the statement »I am the first to break the ice«. So right he was because the imprimatur of his treatise De radiis was dated January 27, 1610, or 32 days before Galileo’s astronomical report Sidereus nuncius. While submitting his manuscript before the censorship, de Dominis was not acquainted with Galileo’s writing and the latter’s parallel efforts directed towards the application of telescope in astronomical observations and not the theory and the construction of instrument. Although de Dominis’s De radiis was published in October 1611 at the earliest, more than a year and a half after Galileo’s Sidereus nuncius, the comparative textual analysis of the first pages of Galileo’s pioneering work and de Dominis’s two indirect objections concerning Galileo leads to the conclusion that de Dominis made no changes in his manuscript after the publication of Galileo’s Sidereus nuncius. That is why de Dominis’s methods and conclusions in De radiis should be viewed in accordance with status quaestionis of the end of 1609.
Even if Galileo’s public demonstration of the telescope on August 25, 1609, did influence the final version and publishing of de Dominis’s treatise, it retained the structure of de Dominis’s approach to optical problems from the time of his professorship (1588-1595): the foundations of geometrical and physical optics, an abridged theory of optical lenses, explanation of the rainbow. In January 1610 at the latest, the theory of lenses was accompanied by a short yet valuable contribution to the theory of the telescope, the first of the kind written after August 25, 1609.
In the »first« part of the treatise de Dominis tried to list all the physical and mathematical suppositions and propositions that he would refer to during the optical research. Some of his statements were true, some incorrect or obscure with exactly described effects. Certain statements were added afterwards in places where they could contribute to the proof. He followed a similar pattern with the basic notions as well. For example, he defined the notion of the angle of view but failed to do the same with the focal length.
After an obscure explanation of the origin of vision, in the »second« part de Dominis expounded the optical lenses despite his scanty knowledge of the basic optical notions; for example, he acquired his understanding of the notion of focal length and focus in the course of the experiments. Moreover, his conclusions on the lenses are entirely based on the experiments. Two chapters on the telescope were neither conceived nor realized as a text which would argue for or against Galileo, thus crediting de Dominis’s treatise with a privileged position, undetected in the historical or philosophical study of Galileo’s epoch. Although de Dominis’s text on the telescope is theoretical and promotive, the distinguished nobleman of Rab harboured doubts about the possible improvements of the instrument regarding its main effect – magnification of an object. Thus he contradicted one of the basic intentions of his treatise – »the marvellous effects« (effectus mirabiles) of the lenses. In his explanation of the rainbow, comprised in the »third« part of the treatise, de Dominis decided on three approaches: a historical survey of the interpretation of the rainbow from Aristotle to the natural philosophers of the Renaissance, commentary on the third book of Aristotle’s Meteorologica, and the original scientific dispute (nova et propria disputatio), based on his own experiments and explanations. Following Aristotle’s starting-point expressed in »Reflection is the cause of the rainbow«, he offered his own interpretations of the origin of the primary and secondary bow. In them the original contribution was accompanied by occasional lack of clarity and certain weaknesses in the illustration of the experiment. De Dominis’s interpretation of the bow proved incomplete where least expected: he was inconsistent in the application of the proposition on the refraction of light on the boundary between two transparent media, although he had clearly formulated it at the beginning of the treatise. In addition, while describing the experiments with the small glass ball filled with water, he failed to distinguish the path of a single light beam and the representation of the ray bundle. De Dominis’s ever-lasting dilemma of whether to follow in the experiment a single ray of light or their bundle made his theoretical explanation and the illustration of the key experiment incomprehensible.
On the pages of his optical treatise the natural philosopher and scientist, de Dominis, combined theory and experiment more frequently than many of his specialists were ready to admit. True, commitment to the experimental result did at times lead towards erroneous theoretical conclusions, just as adherence to a certain theoretical view interfered with the accurate interpretation of the experiment. De Dominis’s optical research was characterized by constant tension between theory and experiment, the result being unpredictible. |
