Talk:Telescope

Need good diagrammes

I am searching for good diagrammes for the different types of telescopes. Anyone have a lead on public domain diagrammes? --Thomas Simmons 20:10, 23 March 2008 (CDT)

Subsection waiting for rewrite

Telescopes as research tools

Zik (2001) notes that before the telescope scientific observation relied on instruments such as Heron's diopter, Levi Ben Gershom's cross-staff, Egnatio Danti's torqvetto astronomico, Tycho's quadrant, Galileo's geometric military compass, and Kepler's ecliptic instrument. At the beginning of the 17th century, however, it was unclear how an instrument such as the telescope could be employed to acquire new information and expand knowledge about the world. To exploit the telescope as a device for astronomical observations Galileo had to establish that telescopic images are not optical defects, imperfections in the eye of the observer, or illusions caused by lenses; and develop procedures for systematically handling errors that may occur during observation and measurement and methods of processing data. Galileo made it clear that in order to measure and interpret natural phenomena accurately, a suitable method and instrument would need to be developed. Historians of science explore the linkage established by Galileo among theory, method, and instrument, in his case the telescope. Although the telescope was not invented through science, Galileo used optics to employ a theory-laden instrument for bridging the gulf between picture and scientific language, between drawing and reporting physical facts, and between merely sketching the world and actually describing it.

Tele versus Telo

Hi Ro. In the article you edited "tele" saying that it is a word in its own right. We have looked and need a reference for this. I can not come up with any. I have reinserted telo (τηλó) but let me know if you come up with the exact word source and we'll change it to tele.--Thomas Simmons 01:04, 23 March 2008 (CDT)

I remember it from school Greek. My Concise Oxford mentions it in the etymology of the prefix thus: (tēle far off) & Wiktionary tells it as follows: From Ancient Greek τηλε- (tèle-), from τηλέ (tèle) "at a distance, far off, far away, far from". In their entry, the prefix is in blue, but the word itself is red, & if you type 'far off' in a Greek language site, it does not get 'tele'. At school we did Homer's Odyssey, so my guess is that Homer uses it as a word, but in later writers it has become a prefix. At the least τηλó needs changing though, omicron to epsilon. Ro Thorpe 10:20, 24 March 2008 (CDT)

Actually Ro, I am referring to roots not whole words. The archaic theory is probably a good one though. I have a Dorlands Med. Dict. which gives tèle too, it is a really old edition, 1981. I have some Orthodox Greek friends in Boston who are Greek scholars--speak the archaic forms fairly naturally evidently and do a lot of :research in this area. I will get their take on it.--Thomas Simmons 15:49, 24 March 2008 (CDT)

Yes, they should have something to say. Ro Thorpe 19:03, 24 March 2008 (CDT)

Hi Ro,

Corroborated. Send me the citation and well put it in the references.--Thomas Simmons 19:37, 25 March 2008 (CDT)

Good, thanks for that. The Oxford (not online) or the Wiktionary or both? Ro Thorpe 20:13, 25 March 2008 (CDT)

Ah, you've done it, very nice. Thanks for your collaboration on that - Ro Thorpe 19:44, 27 March 2008 (CDT)

Digges story

The Digges story goes back a long time but mainstream scholarlship rejects the claims, see Fred Watson, Stargazer: The Life and Times of the Telescope (2006) online reference p. 40; and Vincent Ilardi, Renaissance Vision from Spectacles to Telescopes (2006) online refernce p. 213

A leading historian of astronomy Westfall does NOT mention any telescope in his article on Digges, nor does his biographer Stephem Johnston, who in fact rejects such claims; there is "no evidence" for it Johnston says. No one ever says he saw such a telescope; son Thomas mentions an arrangement of lenses used to magnify objects on earth. Thomas who was an astronomer and senior military person never again mentioned the telescope and never used one or tried to get one built, which is astonishing if he indeed had one at one point during his father's lifetime. The son's statement that the father saw "at seven miles what had been doon at that instant in private places" is too incredible to believe. The son also claims "ye shall discerne any trifle, or read any letter there lying open, especially if the sunne beames come unto it, as plainly as if you were corporally present, although it be distante from you as farre as eye can discrye" which was quite impossible and strongly suggests he never used or invented a telescope. Of course science is a social interaction and claims of secret discoveries are very heavily discounted by historians. Richard Jensen 03:23, 23 March 2008 (CDT)

A leading historian? Mainstream? Send me copies of the sources mentioned above. I do not feel like spending my hard earned cash with Amazon dot Com everytime some one says that the British historians are unqualified to talk about British history. Sorry but I have placed good sources there. It would be appropriate to simply offer the counter arguments. The sources mentioned that do provide the story about the Diggeses involvement are not rumour, they exist. The position one may take from the available sources is in fact better than many of the events we ascribe to, say, the Romans, e,g, the entire events at Adrianople. Look at the mention Vesto Slipher gets for his research in spectral shift and the expansion of the universe yet his papers were published as far back as 1913. Consider how many times John Michell is mentioned when anyone talks about the theoretical underpinnings of black holes yet Cavendish did in fact read his paper to the Royal in the 18th century--Cavendish for pity's sake.

Most importantly, such sweeping deletions and revisions are to be discussed here. If you feel a balance is needed then write one and well discuss this. That is CZ policy. Please bear this in mind. --Thomas Simmons 04:14, 23 March 2008 (CDT)

To wit: Gilbert E Satterthwaite, Department of Physics, Imperial College, London SW7 2BH, UK; Colin Alistair Ronan, Science writer and lecturer. Author of The Cambridge Illustrated History of the World's Science. --Thomas Simmons 04:49, 23 March 2008 (CDT)

Regarding your comment about everytime some one says that the British historians are unqualified to talk about British history - This sort of nationalistic rhetoric is out of place in what should be a dispassionate review of the evidence. (And, by the way, I am a British citizen.) J. Noel Chiappa 09:18, 24 March 2008 (CDT)

Let's take a look at that. I am not really sure what was actually implied was inferred.

One: This is not a passionate review--it is dispassionate. I think it a bit precipitous to presume to know the mental and emotional state of the writer;

Two: Pointing out the very real possibility of nationalist rhetoric is very much a responsible aspect of any informed debate. I can accept that I may have jumped the gun and this is simply not the case. However, consider:

• Watson is Australian. Ilardi is Italian. Westfall is British but he was not addressing the scientific accomplishments per se, he was addressing the socio-political issues.
• The three sources I lined up are all British, John Gribbin, Gilbert E Satterthwaite, and Colin Ronan. The evidence here points to --does not conclusively show--a British versus non-British sources issue. Until the issue of credibility cropped up, I merely considered them sources that had established credentials. I did not seek to gather only those that are British. That issue came up after their credibility was maligned. I have spoken up for their credibility but have certainly not attempted to maintain a supremacy of expertise as has their detractor has done for his sources.

Let me just finish by saying that if you felt that this analysis was meant to be nationalistic and passionate, that was not the intent. Let me also say that having clarified the issue, the writer dictates meaning, the reader merely infers. I hope we have cleared that up.--Thomas Simmons 16:19, 24 March 2008 (CDT)

Digges myth and proposed compromise

Jensen: The idea that Digges invented a telescope is a vastly exaggerated myth that the consensus of recent scholars reject.

Please click on these 2006 book references and read their rejection of the myth. Fred Watson, Stargazer: The Life and Times of the Telescope (2006) online reference p. 40; and Vincent Ilardi, Renaissance Vision from Spectacles to Telescopes (2006) online refernce p. 213 re: Sorry but I have placed good sources there. The sources reject the myth. Thus Westfall, a leading scholar, says Digges invented an astrolabe and never mentions a telescope.

The article cites Johnson (Digges main biographer) who rejects the claim. Johnson in Oxford Dictionary of National Biography (2004): On the basis of comments by his son, occasional claims have been made that Digges devised a reflecting telescope; there is no evidence that his reported optical experimentation led to a working instrument for astronomical observation, but it seems likely that he did indeed use a rather unwieldy lens–mirror combination for terrestrial viewing.

The Gilbert E. Satterthwaite book on astronomy appeared in 1971 and hardly reflects current scholarship.

The only support comes from Colin A. Ronan who died in 1995 and he came to that idea late in life (1991). His article was not refereed and is based entitely on conjecture. In his 1967 book on English astronomy Ronan mentions Leonard Digges only in passing with no mention of these supposed inventions. see page 30

As for balance, while I think one sentence will do I nevertheless do have a compromise solution as follows:

Compromise statement by Jensen: Leonard Digges (?1515-?1559)was an English mathematician and architect who was the first in England to describe the altazimuth theodolitede. On the basis of much later comments by his son, some writers have claimed Digges might have devised a reflecting telescope. Apart from a brief few sentences by his son there is no independent evidence that he invented a working telescope for astronomical observation; it seems likely that he did indeed use a rather unwieldy lens–mirror combination for terrestrial viewing. His son Thomas, who was active in astronomy never claims to have used his father's supposed telescope; no one else claims to have seen it. +

Thomas in 1571 recalled how his father had observed things with "Perspective glasses" on numerous occasions from a considerable distance and with witnesses present: The father "sundrie Times hath by proportionall Glasses duly situate in convenient angles, not onely discovered things farre off, read letters, numbered peeces of money with the very coyne and superscription thereof, cast by some of his freends of purpose uppon Downes in open fields, but also at seven miles declared what had been doon at that instant in private places." +

Colin Ronan and Gilbert Satterthwaite built a working telescope in 2002 from a description found in a report on military and naval inventions, written in 1578 by William Bourne. It comprised a convex lens at the front and a curved mirror at the back, and gave an inverted image magnified 11x. There is no evidence that Bourne himself ever built the proposed telescope. +

end of compromise text Richard Jensen 05:13, 23 March 2008 (CDT)

First off, the clear and unsubstantiated assertion that it is a myth has no place here: "vastly exaggerated myth that the consensus of recent scholars reject." That is just over the top. It is refuted.

Second, scholarship is not about consensus. It is about evidence and the arguments preceding therefrom. And a great many arguments, especially in history, can never be resolved since all the witnesses are dead. Those are the facts.

So, here is yet another excellent scholarly source: someone with a PhD is astrophysics (Cambridge), prolific writer in the history of science, well known, has seen the primary sources herein cited, Visiting Research Fellow in Astronomy, University of Sussex etc. etc. John Gribbin

He says in his Science, a History:

"Leonard Digges invented the theodolite in 1551. About the same time his interest in seeing accurately over long distances led him to invent the reflecting telescope (and almost certainly the refracting telescope as well), although no publicity was given to these inventions at the time)"

The assertion of myth here is constructed by heaping disdain upon one Colin Ronan. Colin was competent, and certainly CUP felt him capable of writing an encyclopedia on the field of astronomy and he certainly had the freedom to look at the primary sources and make his own guesses. The assertion that Gilbert E. Satterthwaite wrote a book more than thirty years ago does not detract from the quality of his work then or now. Gribbin writing in 2002 agrees with that perspective. The sources cited in support of this assertion do not agree that it is a wild myth and while Watson, I did go to the web site were a few choice pages are available, will use the term mainstream scholars he does not generate nearly as much heat over the issue, he simply says that he doubts the Digges had the skills to pull it off. Telescope, by the way, was a word invented some years later.

Another source proffered here, Vincent Ilardi, does not use primary sources while Gribbin and Ronan do. See Ilardi's comments at the bottom of page 213 of the text cited above

Here is what Ilardi's sources can offer, the telescope, if it is constructed as described in Bourne's manuscript and the Pantometria, was not terribly practical. Fine. If that is what the evidence bears that is what it bears. But the assertion that they invented the telescope is a myth is just over the edge.

The dispute is the thing. Not some emotional venting about myths and declaring that my scholars are better than your scholars. In point of fact here is what real scholars do, they agree to disagree, and that really is a consensus. --Thomas Simmons 16:17, 23 March 2008 (CDT)

Telescopes

In light of the comment from Noel, this is moved here:

CZ can't be making claims that are rejected by most scholars. Notable the Digges story. Please argue it out on the telescope-talk page first; CZ does not allow for the kind of reverting-wars that mar Wikipedia Richard Jensen 04:05, 23 March 2008 (CDT)

The following comment which in part discusses the substantive content might better have been posted in Talk:Telescope, where future authors/editors can find it more easily. J. Noel Chiappa 11:26, 23 March 2008 (CDT)

Unbelievable. Most scholars? Someone took a survey and that has been made public? Let's be specific and stick to facts here. You have made massive deletions without consultation, dismissed sources that are employed by the Imperial College and or have written well known works in the field for Cambridge U. Press and then misrepresent the very sources that half-heartedly pronounce who is and who is not mainstream.

To quote one of these mainstream sources From Fred Watson (2006) Stargazer:The life and times of the telescope

"From Pantometria and from writings of another Elizabethan mathematicians, William Bourne (also a contemporary of Thomas Digges), it is clear that the instrument described by the two Diggeses incorporated a dished mirror though probably unlike the modern reflecting telescope. . . .

But what might be called mainstream scholarship upholds an opposing view, namely that the first practical reflecting telescope was constructed by Issac Newton in 1668."

I sum up: Given the difficulty in making an adequate mirror to provide the sort of resolution that Thomas Digges asserts in his words in the Pantometria, it is unlikely that a practical instrument was built by Thomas Digges simply because the technological skill would have most probably been beyond the efforts of the 16th century.

This is no where near a whole-hearted a denunciation of the Diggeses earlier purported in the rationale for the huge deletions nor does the information presented from the source, Colin Ronan, make any pretense to extraordinary accomplishments. The deed was done and the fine instruments we see today had to wait for another time. That sums it up. Issac Newton did not invent the telescope, Galileo did not, Lipperhey did not and it would not be surprising to hear than neither were the Diggeses the first to sort this one out. In fact, there is some possibility that Caesar, to use Watson as a source here, was able to see from afar as well. Galileo is reported to have built his own instruments from a mere traveler's description and was able to see well enough to draw rather detailed views of the lunar aspects.

Furthermore Watson denounces Thomas Digges' claims about his father's powers of resolution. And Watson admits that a mirror is technically much harder to produce than a lens--yet Galileo did make a refractive telescope that had sufficient resolution within one lifetime from Thos. Digges with far less preparation--but Leonard and Thomas could not?

The information offered by Watson certainly makes for a balanced and informed perspective even though it is very possible that he is constructing a straw man to deconstruct but the deletions were wholly unnecessary and well outside the CZ community norm.--Thomas Simmons 05:49, 23 March 2008 (CDT)

Assertions of what is and is not possible here in the text are not really constructive nor honest. I have submitted that it was unlikely given the information available. --Thomas Simmons 16:55, 23 March 2008 (CDT)

A comment here was deleted by The Constabulary on grounds of making complaints about fellow Citizens. If you have a complaint about the behavior of another Citizen, e-mail constables@citizendium.org. It is contrary to Citizendium policy to air your complaints on the wiki. See also CZ:Professionalism.

In the reference

"Thomas Digges: Gentleman and mathematician Stephen Johnston (1994) chapter 2 (pp. 50-106) of, ‘Making mathematical practice: gentlemen, practitioners and artisans in Elizabethan England’ Ph.D. thesis, Cambridge. Available through University of Oxford, Museum of History of Science; Johnson is the chuef biographer and explictly rejects claims for Digges' telescope."

Could not find such a explicit rejection. It would be interesting to see this and read the argument. Is there one available from this source? --Thomas Simmons 21:08, 23 March 2008 (CDT)

Final thoughts

I have contacted and received a response from John Gribbin, the astrophysicists and historian. He directed me to two sources we have already listed, the St. Andrews source [1] and the detailed account from the text of the Pantometria with substantiating arguments from the text of William Bourne and the actual construction and use of the device by Colin Ronan and Gilbert Satterthwaite.[2] It is John Gribbin's considered opinion that there is no controversy, that Leonard Digges did in fact design and construct a device which could, as Colin and Gilbert practically demonstrated, view troop movement as far away as seven miles which requires no more than a magnification of 8 and this was physically tested, not just theoretically conceived both by Leonard Digges, by Mr. Bourne and then confirmed centuries later Colin and Gilbert. Colin Ronan's argument from strictly primary sources which are quoted at length and his practical demonstration of the actual device have at the very least established that during the mid 16th century, well before Galileo constructed his refractive telescope, their was a device that provided sufficient magnification to be of use. What happened after that is a tale typical of great ideas, it languished for years to come, as little more than a curiosity. As to why, that is another story.

I for one am curious to know about the vague reference in Roger Bacon's account of Caesar's approach to the British Isles. Anyone have a clue about that?--Thomas Simmons 19:31, 25 March 2008 (CDT)