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 (Note:  The text is not now complete, included initially are only those references directly to Della Porta himself---SLD)

The Naming of the Telescope


Edward Rosen

Forward by Harlow Shapley

Henry Schuman, New York, 1947


The Statement of the Problem

(Page 3)

Galileo startled his contemporaries by announcing, in the Sideral Messenger,  a number of spectacular astronomical discoveries that had been made possible only by the recent invention of the telescope.  But in this revolutionary little work, which marks the transition from naked-eye to telescopic observation, he did not call the new device a telescope, for that term had not yet been proposed.  Instead, he used organum and instrumentum, which were familiar to his readers in connection with naked-eye observational instruments.  But, more often than both these terms put together, he wrote perspicillum, which had had placed on his title page in plain avowal of his preference.

Kepler shared Galileo's liking for the name perspicillum.  His first reaction to his fellow-Copernican's Sideral Messenger was promptly published as a Conversation with the Sidereal Messenger.  In the Conversation he ....


The Attribution to Cesi

(Page 6)

In some quarters the credit for devising the term telescope is assigned to Frederick (Federico) Cesi, founder and president of the Academy of the Lynxes (Accademia dei lincei), an association for the advancement of science, whose most illustrious member was Galileo.  The attribution to Cesi rests ultimately on the evidence of two contemporaries, Della Porta and John Faber.  Their testimony is not entirely independent, and we shall consequently consider the earlier statement first.

John Baptist (Giovanni Battista, Giambattista) Della Porta was vice-president of the Academy of the Lynxes and chairman of its Naples branch.  In an undated letter to an unspecified correspondent Della Porta says:  "You write that you are greatly surprised that whereas Englishmen, Belgians, Frenchmen, Italians and Germans claim for themselves the invention of the telescope, I, the actual inventor, am the only one to remain silent amid so great a clamor."  He then goes on to explain how the credit for "his invention" slipped away from him:  "To many men have I shown the telescope (it is a pleasure to use this name, which was devised by my president).  Upon their return to their own countries, they ascribe the invention to themselves."

In this letter, then, Della Porta does more than "appear to attribute the name to Prince Cesi," as the Oxford English Dictionary would have said it; on the contrary, he flatly asserts, as we have just seen, that Cesi coined the word telescope:  Telescopium multis ostendi (lubet hoc uti nomine, a meo principe reperto).  Incidentally, the word principe in this sentence was misinterpreted by the Oxford English Dictionary, because it accepted an erroneous date for the letter.  It is perfectly true that Cesi acquired the title of prince (princeps) early in 1613.  But from the time of his foundation of the Academy at Rome in 1603 he had been its perpetual president.  From 1613, then until his death in 1630 Cesi was designated princeps in two distinct capacities, as president of the Academy of the Lynxes and as Prince of St. Angelo and St. Polo.  But before 1613 princeps, as applied to Cesi, referred only to his presidency of the Academy.  Now Della Porta's letter was written prior to 1613, as will be shown below.  Hence principe in the quoted sentence means president, not prince.


First Witness for Cesi:

John Baptist Della Porta

(Page 7)

Before we accept Della Porta's statement at face value, it behooves us to weigh carefully certain facts about the man and the circumstances under which he wrote the letter in question.  In the first place, he cannot in all justice be described as having been meticulously accurate even in his assertions about himself and his writings. Secondly, he displayed a distinct tendency to defer to persons of titled rank, without regard to their intellectual attainments.  Lastly, he was not in immediate contact with Cesi and Cesi's circle of close friends at the time when the term telescope was originated.  These considerations, which tend to undermine our confidence in Della Porta's testimony, deserve some elucidation.

Let us begin our test of his autobiographical reliability by asking at what age he published his first and major work, Natural Magic.  Of all his numerous scientific and literary writings, produced during an unusually prolonged and prolific career, his Magic attained the widest distribution, through successive editions in various languages.  In its original form, it consisted of four books, and was first printed at Naples, his native city, in 1558;  this first edition was dedicated to Philip II and contained a preface.  An amplified version in twenty books, bearing a second preface, first appeared at Naples in 1589.

In his Biblioteca matematica italiana Pietro Riccardi lists a non-existent edition in twenty books of Naples 1569.  This fictitious entry might perhaps be ignored, had it not been accepted by so eminent an authority as Antonio Favaro, who was responsible for the national edition of Galileo's works.  Yet two separate lines of argument merge to prove that an edition of 1569 is out of the question.  In the first place, Della Porta complains in the second preface that "a certain Frenchman" in his book on Oenomania thinks that I am an evil magician and that my book, which was printed some time ago, deserves to be burned."  Despite the weird misprint, the Frenchman was long ago identified as John Bodin.  In the preface to his De la demonomaie des sorciers (Paris, 1580), Bodin mentioned "a great Neapolitan sorcerer"; later on he spoke more explicitly of "a recent book on Natural Magic by a Neapolitan...which deserves to be burned."  In the second place, the approval by the ecclesiastical censor of the expanded Magic is dated August 9, 1588.  Hence Riccardi's 1569 edition in twenty books must be dismissed as a ghost.  It is regrettable that in cataloging the editions of the Magic Riccardi did not distinguish with sufficient care between the original version in four books and the enlarged version in twenty books.

Still a third line of argument demonstrates that the amplified Magic could not have been published in 1569.  For in the second preface Della Porta described himself as fifty years old.  And the accompanying portrait of the author carried an inscription indicating that he sat for the artist in his fiftieth year.  Now while discussing the great eruption which shook the Naples area and raised Mone Nuovo overnight, he remarked that he was an infant when it occurred.  Through an unfortunate misprint, the year was given as 1528.  But Della Porta's description of the creation of Monte Nuovo and his dating of the event at the end of September, in close agreement with the reports of older contemporaries, dispel any doubt that he referred to the catastrophe of 1538.  Since he was a mere child in 1538, his fiftieth year obviously fell long after 1569.

But the date of his birth can be ascertained with somewhat greater precision from his formal enrollment as a member of the Academy of the Lynxes on July 6, 1610.  On that occasion, when he signed the official register, he wrote with his own hand that he was then in his seventy-fifth year.  Furthermore, in a letter of December 6, 1611, he gave his age as seventy-six.  According to these two documents, then, he must have been born between December 7, 1534 and July 6, 1535 (if we may disregard the shift from the Julian calendar to the Gregorian).

Should any modern reader feel dissatisfied with our lack of certainty regarding the exact date, let him contemplate the floundering of the Lynxes.  Cesi prepared a memorandum to serve as the basis for Faber's draft of the Academy's obituary notice of Della Porta.  In the latter document we read that Della Porta "died an old man of about 84."  Yet Cesi communicated the news of Della Porta's death to Faber in a letter of February 21, 1615, less then five years after Della Porta himself had recorded his age in the Academy's official papers as 75.

On the basis of the evidence indicated above, which fixes Della Porta's birth in 1535 (or in the last three and a half weeks of 1534); for the sake of brevity, let us agree to attach a similar qualification to all our subsequent statements about his chronology) we may date the composition of the second preface of the Magic in 1585.  Now the opening words of this preface speak of the work as almost finished, a report of progress that tallies fairly well with the first appearance of the expanded version in 1589.  So far, so good.  But here's the rub.  The second preface avers that when the Magic was first printed, Della Porta was a child prodigy, scarcely fifteen years old, and that thirty-five years have elapsed since the first edition.  These assertions create an air of arithmetical consistency between the alleged publication of the first edition in the author's fifteenth year and teh composition of the second preface in his fiftieth year.  But this interval could be thirty-five years only if the Magic had been first published in 1550.  Yet Della Porta dedicated the first edition to Philip II, Most Serene and Catholic King, and addressed him again at the end of Book IV; but that Hapsburg worth did not ascend the throne of Spain until 1556.  Incontrovertibly, the first edition came out in 1558, when Della Porta was at least twenty-two, not fifteen.  Are we not then obliged to conclude that in the second preface he exaggerated the precocity of his youthful accomplishments?

During the following year he gave a more credible account in a private letter not intended for publication.  On June 27, 1586 he mentioned "the book which I began more than thirty years ago."  Here he pictured the composition of the Magic, then, as beginning not long before 1556.  That was the year in which Philip II was crowned and Della Porta attained his majority.  Two years later the Magic went into its first edition.  All these details obviously merge into an entirely plausible story.  But if we have reconstructed that story correctly, then the second preface stands convicted of an undeniable falsification.

To some scholars such a verdict seems distasteful.  They seek to avert it, but in their effort to save Della Porta's face, they distort his language.  With his birth fixed in 1535, and the first edition of the Magic anchored to 1558 they are of course precluded from endorsing his claim that he was fifteen when the book was first published.  Hence they resort to portraying Della Porta as merely "composing" the Magic at the age of fifteen, or "commencing" it then or "studying" the subject, or "caressing the idea" of the book.  Yet in the second preface Della Porta plainly says that in his fifteenth year the work was printed (excusum) and published (editum).  Now excusum and editum were technical terms of the book trade, referring unambiguously to the final stages of a process which normally commences with study of a subject and composition of a manuscript.  The historians of the eighteenth century were entirely clear about the precise nature of Della Porta's boast, but that was before the trolley car of modern research was driven down the wrong track.  Don't all these recent divergent misconstructions, however well intended, flow from a manifest reluctance to acknowledge that a man of Della Porta's renown may sometimes have been, shall we say, somewhat unreliable?  We may have excellent grounds for believing that his intellect ripened at an exceptionally early age; but his published assertion that he was fifteen when the Magic first appeared conflicts with the facts as we know them.

Now that we have ascertained, within the limits of the available evidence, Della Porta's true age at the time of the first edition of the Magic, a related aspect of the question awaits out attention.  Long ago a sharp contrast was noted between the self-portraits in the two prefaces of the Magic.  As we have already seen the second preface depicts an infant prodigy of fifteen bringing out the first edition.  But the first edition itself presents a somewhat different picture.  To be sure, its preface begins by describing the work as precocious.  But in the dedication the author declares:  "From early boyhood I have long considered with a certain unwearied interest..."  And in the preface he says:  "From my early years I had an innate desire to hear and learn these things, a desire which grew as my age increased."  He turns teh volume over to his readers with these words:  Receive then, attentive readers, the outcome of long labors, accomplished not without the utmost application, sleeplessness, expense and trouble."  Surely these expressions were not calculated to evoke the figure of a teen-age author.  Even a confirmed advocate of Della Port's trustworthiness must grant that a certain degree of maturity is implied.  If then in his early twenties Della Porta unduly emphasized his maturity, and in his middle years retrospectively overstated his precocity, can the impartial student be blamed for feeling somewhat skeptical regarding his pronouncements about himself, let alone others?


Della Porta's Letter of Attribution

(Page 16)

Now that we have become acquainted with our first witness, let us look a little more closely at the letter in which he attributes the origin of the term telescope to Cesi.  In this letter, it will be recalled, Della Porta claimed for himself the invention of the telescope.  But he had raised not great outcry in his own behalf, he explains, because he was content to rest on the statement of his case by Kepler, who "shows that in my Natural Magic, Book XVII, Chapter 10, the construction seems to be set forth, and the mathematical demonstrations in my Refraction, Book VIII; these works I published twenty-five years ago."

This brief observation fairly bristles with historical difficulties, but before we can deal with them, we must first agree upon the wording.  The manuscript of the letter, as written in Della Porta's own hand, still survives; and on the basis of this autograph, a text was published by Boncompagni in 1846 and Gabrieli in 1939.  In their version, the sentence under examination is patently ungrammatical.  Della Porta evidently started out with one sort of construction in mind and unconsciously shifted, as he proceeded, to an incompatible alternative.  Odescalchi, who first published the letter in 1806, sought not repair the faulty syntax by substituting publicave, clarissime contineri for the last two words of the authentic reading.  But his emendation, while healing the sentence structurally, would transform it into a somewhat shaper claim than the Neapolitan savant intended.  Let us therefore adhere  to the authentic and lame version, consoling ourselves with the reflection that authors of even a greater reputation the Della Porta at times disappoint the purists among their admirers.

With out textural problem thus summarily disposed of, let us try to disentangle the historical perplexities.  To begin with, Della Porta's De refractione optices parte was published at Naples in 1593.  Hence he could not have written this letter twenty-five years later (which would be 1618), since he died early in 1615.  Moreover, there is nothing in Kepler's voluminous writings, so far as I know, to substantiate Della Porta's assertion that Kepler supported his claim by referring to his Refraction.  In fact, Kepler lamented his ability to secure a copy of that treatise.  To be sure, he voiced this complaint back to 1604, nearly a decade before our letter.  But more than a decade had already elapsed since the publication of the Refraction; and there is no indication, to my knowledge, that he ever succeeded in getting hold of the volume subsequently.  Even if he had, he could not have produced it in support of Della Porta's claim, for it does not contain any "mathematical demonstrations" basic to the telescope.  

In connection with the Magic, however, Della Porta stands on firm ground.  In the Conversation with the Sidereal Messenger, addressed to Galileo on April 19, 1610, Kepler did indeed cite the Magic ( Natural Magic, Book XVII, Chapter 10), praising Della Porta for having there suggested combining a concave with a convex lens in a single optical system.  Yet Kepler felt that in the very next chapter Della Porta's presentation was "so obscure that you don't know what he's saying; whether he's still talking about transparent lenses, as previously, or introducing an opaque polished mirror."  And under the mistaken impression that Della Porta was no longer alive, Kepler went on the relate that the Emperor - Kepler was at that time Imperial Mathematician to Rudolph II of the Holy Roman Empire - used to ask his opinion quite frequently about Della Porta's devices.  Kepler admits "disparaging them vigorously, and no wonder, for he obviously mixes up the incredible with the probable."  We should not be surprised, I suppose, that Della Porta called attention only to Kepler's specific laudatory comment, and failed to mention has general adverse judgment.  Presumably Della Porta felt man's normal craving for the respect and admiration of his fellows, and the corresponding distaste for their condemnation.

Book XVII of the Magic, as we have already seen, first appeared in print in the amplified version of 1589.  Yet it is noteworthy that no scholar has enough confidence in Della Porta's meticulousness to risk dating our letter in 1614, on the ground that it speaks of the Magic having been published twenty-five years before.  Govi for instance, wavered between 1611 and 1612.  Fiorentino and Vavaro chose 1613; Spampanato hesitated between 1612 and 1613; and Gabrieli, after favoring 1611 and 1612 and 1613, finally decided on 1612.  We shall see later on that there is some reason to prefer the spring of 1611.

The foregoing observations should not be construed to paint Della Porta as an inveterate, conscious liar.  It must be remembered that he composed the letter under review in his late seventies.  And as an integrated personality, his mental attitude as a writer of works of the imagination for the theatre quite likely carried over to his handling of scientific themes and familiar correspondence.  In view of his recognized inaccuracy we are amply justified, I submit, in disregarding his explicitly attribution of the term telescope to Cesi.  As a possible motive for his conduct, we should bear in mind his habitual inclination to confer undeserved intellectual honors on members of the aristocracy.  It is ironical to bear Cesi, himself a nobleman, report in a tone of some annoyance that he found it necessary to reprove this predisposition of Della Porta's.  The latter, finally was far away in Naples when the the new term was introduced.  But our next witness, John Faber, was on the scene in Rome when it all happened.

Before considering his testimony, however, we should take into account a letter composed by Francis Stelluti, one of the four charter members of the Lynxes.  Addressing his brother from Rome on September 15, 1610, Stelluti remarks:

I suppose that by this time you have already seen Galileo, that is, his Sideral Messenger, and the great things he says.  But now Kepler, a pupil of Tycho's has written against him, and a copy of the book has already come down from Venice to Father Clavius.  According to Kepler, Galileo makes himself out to be the inventor of the instrument (instrumento), but more than thirty years ago John Baptist Della Porta described it in his Natural Magic and mentioned it in his book on Refraction also.  And so poor Galileo will look foolish; But meanwhile the Grand Duke has given him 800 piastres, and the Council of Venice has raised his salary.

(Page 21)


John Faber

We are now ready to hear our second witness, the physician and naturalist, John Faber (1574-1629).  For many years a small group of the Lynxes interested in natural history collaborated on a treatise illustrating the flora and fauna of Mexico.  To this work Faber contributed a long section on animals, wherein he describes "the optical tube...which it has pleased me to call after the model of the telescope, a microscope, because it permits a view of minute things."  Having thus introduced to the world the term microscope, he digresses to discuss the origin of the telescope:

And since this marvelous optical instrument has been mentioned here, by means of which we see the most distant objects as though they were quite close, I have thought it worth while to bestow on its inventors their due fame.  John Baptist Della Porta, a member of the Lynxes, was the first to describe accurately, more than forty years ago, its theory and structure in his Natural Magick, and its mathematical roots so to speak, in his little book on Refraction.  Therefore he was the first creator of this invention as well as of many other remarkable innovations, both in mathematics and physics.  The German, John Kepler, who is the Imperial Mathematician, recognizing this fact, sincerely and spontaneously proclaims it to all men.

(Page. 24)

Faber continues as follows:

But we readily admit that some highly expert German or Dutch workman was the first to contrive and, perhaps by accident, to build the instrument.  Then Galileo, while a professor at Padua, merely hearing of it and without previously seeing it, made something similar of his own accord.  He showed his invention first at Venice and Padua, as is set forth in his book written in the Italian language and entitled Il saggiatore.  Whatever shouts or cries the envious may raise, Galileo not only constructed the instrument after scarcely hearing a rumor, but he also perfected it to such an exten that he was the first to turn this tube syward and to describe to all men all those marvels which I have already described in the dedication.

 At the same time in Rome the president of the Lynxes, the most illustrious Frederick Cesi, having heard only a rumor from Belgium, constructed the very instrument and passed it around among very many noblemen in the city.  He also thought up the name telescope and bestowed in on the instrument.  Not many months later Galileo came to Rome.  Cesi entertained him at dinner on the Janiculum, together with Anthony Persio;  John Demisiani;  John Terrentius; Francis Piffari, the Camaldolese mathematician; and Julius Caesar Lagalla, the leader of the peripatetics in the city;  I was there too.  (Cesi often gave such dinners on other occasions, for he understands no pleasures apart from scholarship and scholars.)  Before dining, we viewed some sights in the heavens and on the earth, and held philosophical discussions.  While the instrument was in use, Cesi repeated the name telescope many times.  It pleased everybody so much and was so welcome that it subsequently spread throughout the city and the world.

(Page 29)

To be continued....

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