Astrolabes

[Captain Jacob Badger]

http://mc.net/~jcm/jans/navig.htm

and fer those who wants t' build thar own...(ye may need t' scroll down the page s'wat

http://celestaire.com/pdf/sextants.pdf

what drake did...

http://www.longcamp.com/nav.html

history of...

http://www.mat.uc.pt/~helios/Mestre/Novemb...00/H61iflan.htm

can't find the 'quote' from Morgans Logs.....will do tho....just need t' remem where they was...

[blackjohn]

Do you find that the expansion and contraction of a wooden astrolabe (from wetting and drying) affects the accuracy?

One could ask the same question about the paper/parchment chart!

[Captain Jacob Badger]

nice....

[Fox]

if anyone tries to tell you that it is possible to sight stars with a wooden astrolabe aboard a ship, he's spinning a mighty gross yarn

As I've said before, an astrolabe is not the best instrument for sighting stars anyway IMHE, but I HAVE used a wooden astrolabe (more than one in fact) at sea for solar sightings and achieved very satisfactory results. What part of that do you not get? Or are you suggesting that I'm spinning a yarn? In which case, pistols at dawn it is, I'll let you nominate the place

QUOTE (Silver Steele @ Jun 10 2005, 10:48 PM)

Source:  Websters Instrument Makers Database - Letter F

Ruy Falerior, Spain, 1519, MIM

Made one wooden astrolabe and six wooden quadrants for Magellan.

Excellent find, but this may also be an astronomical astrolabe to calculate sunrise /sunset, the transit of sundry stars in different latitudes or the position of planets. It does not necessarily indicate a Mariner's astrolabes.

True, it may be, BUT a planispheric astrolabe is ten times more affected by the wind than a mariner's astrolabe (due to its solid construction), so if you reckon that Magellan was able to use a wooden planispheric astrolabe at sea then you can really have no sensible objection to the possibility of using a wooden mariner's astrolabe - though I have every faith that you will find one.

One might also add that a wooden astrolabe as used on land by de Gama will be just as affected by wind as a wooden astrolabe used on board ship, thus the real problem for de Gama was the heaving of the deck. Since the heaving of a deck will affect wooden and metal astrolabes to the same extent one might just as well use a wooden instrument as a metal one. That is of course, if one accepts that de Gama knew what he was about when it came to the practical aspects of navigation - and I'm inclined to.

[Capt DaggezEber]

I have a small medalian size (1.5inchs diameter) astrolab replica with moving parts, how can I tell if it is land or water type.

Oh and it be metal...arrr

[Capn_Enigma]

I HAVE used a wooden astrolabe (more than one in fact) at sea for solar sightings and achieved very satisfactory results.

Once or twice, in pondlike conditions and still in sight of land? Or over months, in bad weather in the middle of the North and South Atlantic, Mediterranean or Caribbean, where I have used my metal astrolabes?

Be it the former, I am sorry to say that your comprehensive experiences bear little to no value for me.

True, it may be, BUT a planispheric astrolabe is ten times more affected by the wind than a mariner's astrolabe (due to its solid construction), so if you reckon that Magellan was able to use a wooden planispheric astrolabe at sea then you can really have no sensible objection to the possibility of using a wooden mariner's astrolabe

Are you at all aware of the fact that a planispheric astrolabe has lots of other uses apart from sighting? It was most frequently used as an analog astronomical computer to determine sunrise, -set, culmination of stars etc. Magellan may have used it for those purposes and those purposes only.

[Capn_Enigma]

Oh and it be metal...arrr

First off, wise choice!

how can I tell if it is land or water type.

Does it roughly look like this?

Then it's an astronomical astrolabe, extremely useful as an astronomical computer.

If it looks like this

Congratulations! You have a Mariner's Astrolabe, used by discriminating navigators worldwide!

[Cap'n Pete Straw]

... allow me to quote from Dennis Fisher's excellent book Latitude Hooks and Azimuth Rings (p. 25 f)...

Everyone (Moderator especially) please forgive what may sound like fanning the fires of a flame war, but that is not my intent. I have here a (wooden, not metal) bucket of water to throw on the flames. (...Although some may consider the liquid to be kerosene...)

And I sincerely apologize for the length of this post, but I do not feel I can edit it further without losing the integrity of the argument. And I apologize for ever listing a sextant among my late 1700s gear, which seemed to be the original source of this flamy thread...

...But...

Capn Enigma, you proved the case yourself in your own cited reference. In "resting your case," you conclusively proved the "silly" hypothesis that "wooden astrolabes were used aboard ships once and for all."

Flame against me if you will (and I will not fight back, as I really have no interest in arguing with any of you), but I want to point out that you provided concrete evidence that these WERE used aboard ships (unless you wish to recant your own authoritative evidence). And no one else had to help you do it.

Your quoted "excellent" authoritative source stated:

"But taking accurate sights with an astrolabe...was next to impossible aboard a ship at sea."

"Next to impossible" is not "impossible." In making this statement, the author declares that it was tried, and it was done. Clearly it was not the preferred method, but they were used. Otherwise, your author could not make this statement.

Your source continues:

"Usually three men were required. One braced his back against the mainmast [...] Another sighted the star. The third would read the angular height from the degree scale..."

Proof positive! Your source states the methods, convoluted as they were, to overcome the handicap of owning a lightweight (and I presume you cited this reference to indicate a wooden) astrolabe! This ritual would not exist if heavy metal astrolabes were the ONLY astrolabes used aboard ships -- but you offer the logical and irrefutable argument that (1) if this method existed, then (2) wooden and/or small, lightweight astrolabes existed and (3) they were used aboard ships with (4) limited degrees of success requiring complicated methods of steadying them and taking readings. Q.E.D. Granted this same method was not used by all, but your source implies that this method, or something similarly complicated, was employed by EVERY crew who had to rely on a wooden or relatively lightweight astrolabe depending on prevailing wind conditions.

Wait.... there's more:

"Lining up the dimly shining Polaris through pinhole sights on a pitching, rolling deck demanded more skill than most seamen had, and if a breeze caught the instrument, sight taking was nearly impossible."

How can the author make this statement? It is pure speculation, and he has no proof whatsoever to back it up! HE IS A LIAR! Since this could NOT have happened (of course not -- lightweight wooden astrolabes were not used aboard ships, right? ) the author is purely speculative about this hypothetical situation and the entire referenced source must be abandoned...

...Unless the author is NOT lying... Are we suggesting that he has evidence to back it up? If, as stated, lining up Polaris in a blah, blah, blah was nearly impossible, then the author suggests that "most" sailors abandoned lightweight wooden astrolabes because they were considered inferior, or, more accurately, becuase "most" sailors lacked the skill required to use them. But first they had to be used in order for this to be known. Experience comes from trial AND from error.

And to reuse part of that same quote:

"... sight taking was nearly impossible."

Once again, "nearly impossible" is not "impossible." Trust me, I have done many things in my life that many people have gone on record as stating are "nearly impossible." The use of this statement by the author again states that sight taking was attempted on board ship -- otherwise the statement could not be made.... and this is an "excellent" authoritative source, right?

Why, I would not at all be surprised if someone -- maybe someone right here in this very forum -- could quite possibly have used a wooden astrolabe (more than one in fact) at sea for solar sightings and achieved very satisfactory results. Yet someone else -- perhaps most people -- might easily declare this actual event as being "nearly impossible." Incredulity does not negate reality. Used aboard ship and failing = used aboard ship. Degree of success or failure does not dictate fact.

I really tire of this, but there is actually more convincing evidence to be had...

"Vasco da Gama circumvented these problems [common on smaller marine instruments] by going ashore to take sights with a large, wooden astrolabe hung from a tree branch."

Vasco da Gama had a wooden astrolabe aboard his ship. He adopted the practice of going ashore to use it to get accurate readings because his wooden astrolabe (due to its size) gave more accurate readings than a small one (which he either did or did not have, and which either was or was not made from metal). Pure logic raises this question: How did this experienced sailor determine that his wooden astrolabe would give him better readings on land (inconvenient to land everytime he wanted to get an accurate reading) than onboard his ship (easy to simply whip it out and use it) ? Hmmm... you don't think he could have actually used it on board his ship, do you? Would trail and error have possibly suggested to him that he could get better readings by using it ashore?

And another "proof positive" is that Vasco da Gama had a wooden astrolabe on his ship with him. He did not land, cut down a tree, have a carpenter fashion for him a wooden astrolabe, use it for a reading, and then abandon the instrument on the beach while going back on board his ship. While the original argument here (I think I have lost sight of it amongst the flames) may be that wooden astrolabes were never ever ever used aboard ship, the historical fact that a named sailor specifically carried a wooden astrolabe amongst his gear for an intended purpose places the wooden astrolabe among the list of legitimate nautical gear. (Large axes were typically not used on board ship, they were used to cut down trees on land for new masts -- yet they were considered essential nautical gear. Such a list could go on, but that is not my purpose.)

Another application of sheer logic indicates the silliness of declaring that wooden astrolabes were not used on board ship: When lost at sea, with no land in sight, and forced with the unfortunate choice to drift aimlessly or to attempt a navigational decision based on perhaps faulty readings derived from the wooden astrolabe on board (typically saved for landfall readings), what would you do? One might, indeed, attempt the "nearly imposssible."

*sigh* There is still more:

But for mariners far out at sea, the astrolabe was of limited use. Columbus had an astrolabe on his first voyage, but apparently never got accurate readings from it."

Can anyone tell me what this statement means? Astrolabes were never used at all? Astrolabes were used? I read this to mean: regardless of construction, the author indicates that astrolabes were (or are) considered to be inferior navigational tools. All of them. Does this suggest that astrolabes were never ever carried at all by anyone ever? No, we know this not to be true, and the author states that they were used on board ship (by Columbus, to name one person). It is a fact (and I am NOT going to cite references for this, there are too many, and you can easily find them yourself) that MOST astrolabes that now exist in collections were given as ornate gifts to heads of state and important VIPs, etc., and not intended for actual use. But many were carried to sea and used for this purpose. And not all of those used at sea were ornate models that cost a King's Rnasom. Some were plain. Some were cheap. Some (oh -- the author implies most, if not all) were inaccurate....

...Dare I suggest that some were wood? Pure, sheer logic indicates that not every crew was able to obtain a metal astrolabe. How did they dare go to sea? Wooden astrolabes were made.... why did anyone make them, as they were not suitable for non-navigational gifts?

Thank you, Capn Enigma. You have convinced me. You have proven me wrong. My own presumptions were that wooden astrolabes were NOT used aboard ships. But I have seen the error of this short-sightedness, and I now know better. The rest of you: back off. Capn Enigma has shown all of us that wooden astrolabes were used aboard ships, although they were considered inferior and were not the device of choice. And I will defend against anyone who tries to prove Capn Enigma wrong in his proven statements to this point.

...Although I do not see how wooden astrolabe would survive the raging fury of a flame war...

[Capn_Enigma]

My dear Sir,

as far as I am concerned, you can use wooden astrolabes until you turn blue in your face. Use an aluminum or a plastic one if you please, I really could not care less.

But make no mistake, they are not authentic.

I challenge you to show me a single 16th, 17th or 18th century wooden Mariner's Astrolabe.

And, as you are obviously as of yet still ignorant of the shape of a Mariner's Astrolabe, this be it:

Always your obedient &c &c.

[Lady Seahawke]

Cap Straw....I agree...I too must say

  And I apologize for ever listing a sextant among my late 1700s gear, which seemed to be the original source of this flamy thread...

Since one of the beginning posts stated the uses of sextant has been mentioned twice and I was the other one of the two...

[Capt DaggezEber]

Oh and it be metal...arrr

First off, wise choice!

how can I tell if it is land or water type.

Does it roughly look like this?

Then it's an astronomical astrolabe, extremely useful as an astronomical computer.

Yes more like this with lots of cool looking clock-like parts and tiny numbers like dates cover the back. :)

[Capn_Enigma]

These astronomical (or planispheric) astrolabes are especially beautiful.

Can you take it apart and change the tablet within to another latitude or is it fixed to one latitude?

[Fox]

Firstly, thankyou Cap'n Straw for saving me from writing a long reply myself (which I must own would have been less long and less eloquent).

Secondly, if there are any mediums present would they mind having a chat with de Gama and Magellan and telling them that their astrolabes are inauthentic?

Thirdly, Cap'n Enigma, lighten up! If you'd made the very sensible argument "metal astrolabes are far better than wooden astrolabes, both in terms of ease of use and of robustness (is that a word?), so would have been the preferred tools of GAoP navigators" then everyone would have sagely nodded and thought what a sensible chap you were. On the other hand by blustering about that wooden astrolabes were never used on board ships you've just made yourself look a bit daft. May I ask something? In all your wide experience, how many times have you tried using wooden astrolabes? I mean, you tell us that you've used metal ones all over the place, and I'm sure they've worked well for you, but how many wooden ones have you used and how were they constructed?

Finally, Cap'n Straw again, you wrote:

And I apologize for ever listing a sextant among my late 1700s gear, which seemed to be the original source of this flamy thread...

Unless that's a typo you'd better apologise twice. Sextants would be absolutely fine for late 1700s living history.

[Cap'n Pete Straw]

...as far as I am concerned, you can use wooden astrolabes until you turn blue in your face... But make no mistake, they are not authentic.

Sir, you are utterly mistaken. Capn Enigma has already proved beyond a shadow of a doubt that wooden astrolabes are, indeed authentic: he has proven that they were used aboard ships. If you are in doubt, please refer to the irrefutable evidence which he previously quoted from: "Dennis Fisher's excellent book Latitude Hooks and Azimuth Rings (p. 25 f)..." & etc. The full bibliographical reference is cited in his previous post. You should bone up on your nautical history, sir. Capn Enigma has done us all a great service proving that wooden astrolabes were used on board ships (although with limited accuracy), and we all owe him our gratitude. Unless you are calling Capn Enigma a liar. Then, sir, I think you owe him an apology.

Foxe: you asked:

"In all your wide experience, how many times have you tried using wooden astrolabes?

I had been chomping at the bit waiting for someone to ask this, as that is a hugely relevant point. Related to that question are three or four more points I would like to have addressed regarding authenticity, practice, common sense and skill, but I said more than enough, IMHO.

Also, Foxe, regarding my "Pirate Top Ten" list, you said:

(Interesting... 'I saw no need to refute a truthful statement'... Hmmm, why do I think that sentence does not belong in thius topic thread...?)

Yes, I know that. But it was such a minor point, I understood what you were trying to say, there were no feelings hurt, you were not innaccurate, and I saw no need to refute a truthful statement. (Interesting... 'I saw no need to refute a truthful statement'... Hmmm, why do I think that sentence does not belong in this topic thread...?) I am working toward more of a mid-to-late 1700s impression, and you were making a statement regarding the Golden (Great?) Age of Piracy -- there was no conflict of interest.

Next,

"I challenge you to show me a single 16th, 17th or 18th century wooden Mariner's Astrolabe."

Can it be from the early 19th century? 'Cuz I have an ace in the hole for that one.

However, for the true answer to your question, I refer you to Capn Enigma, as he has already shown us specific evidence of a wooden mariner's astrolabe from the Fifteenth Century. Of course, you must already be aware of this, as I see you specified 16, 17 & 18th centuries. I have already told you I will not tolerate your continued attemopts to refute the concrete evidence with which Capn Enigma has already provided us. Capn Enigma has proven the existance of wodden mariner's astrolabes and I will hear no more from ignorant naysayers to his well-researched historical evidence.

[Cap'n Pete Straw]

I am so terribly sorry, the cut-and-paste thing defaulted to another italicized statement. That paragraph should have read as follows:

Also, Foxe, regarding my "Pirate Top Ten" list, you said:

Unless that's a typo you'd better apologise twice. Sextants would be absolutely fine for late 1700s living history.

Yes, I know that. But it was such a minor point, I understood what you were trying to say, there were no feelings hurt, you were not innaccurate, and I saw no need to refute a truthful statement. (Interesting... 'I saw no need to refute a truthful statement'... Hmmm, why do I think that sentence does not belong in this topic thread...?) I am working toward more of a mid-to-late 1700s impression, and you were making a statement regarding the Golden (Great?) Age of Piracy -- there was no conflict of interest.

It pays to proofread these things, eh? How embarrassing! I mean, I could have accidentally made an utterly stupid statement that I could not back up, such as "Though a wooden astrolabe is nice for learning how to use it, they were never used aboard a vessel." I mean, how embarrasing could that have been, huh?

[Capn_Enigma]

Foxe: I said that wooden Mariner's Astrolabes were never used on board a ship. If you feel the need to quote me, please be so kind as to quote me properly.

Also, I made 3 wooden astrolabes in all (2 planispheric and 1 Mariner's), using them onboard my various ships. Thereafter, I decided to abandon wood since it has no practical value aside from being cheap and easy to machine. My astrolabes / other instruments after that are brass, also used aboard my ships.

How many did you make and on what ships did you use them?

Capt Straw:

You, Sir, are obviously even too ignorant to realize that there two very different types of astrolabes (Planispheric and Mariner's) and I shall not waste my time again to teach the difference to the likes of you.

Your continuous efforts to ridicule me are thwarted by the fact that you are not even familiar with the most basic of knowledge in this area and trying to lecture others while being unladen with any knowlwdge yourself is ... foolhardy.

Forgive me, but unless you display that you do have command of at least that certain basic level of expertise in this field, you, Sir, are not a conversational partner for me.

I challenged you to show me any 16th, 17th and 18th century wooden Mariner's Astrolabes, because before that time, Mariner's Astrolabes were not "invented", and after that period, they were obsolete due to the backstaff and octant.

[Fox]

I wouldn't want to be accused of misquoting. The initial comment from Cap'n Enigma which sparked this furious debate was, and I quote:

Though a wooden astrolabe is nice for learning how to use it, they were never used aboard a vessel.

Later on in the argument Cap'n Enigma did move the goalposts by going on to specify that he was only talking about mariners' astrolabes. Recently he has moved them again by revealing that far from "never", he is actually talking about a specific time frame. Just to clear that up.

Now, Cap'n Enigma. I have built 5 different wooden astrolabes, and I own 2 metal ones. I have used them on several trips on both sailing and motor vessels in the English Channel, the North Atlantic, the Irish Sea and the North Sea. Weather conditions have varied from beautiful to, well, too poor to take readings. Of course, we read regularly of ships going days without taking sightings because of weather conditions, though I'm sure your fine astrolabes are perfect for taking sightings even in the most adverse conditions.

I have one further question for you. Is there a reason you're so damn rude to people? I mean, you've implied both that I am a liar and that I bore you (not to much to keep you coming back though...), you've quite blatantly stated others' ignorance. Are you so insecure that you can't hold a debate without resorting to insulting people? Were you bullied as a child?

I'd like to know your reasons for thinking that the astrolabe was made obsolete in the 18th century by the back staff and octant. As I'm sure you know, the backstaff was invented in the 16th century, so if it made the astrolabe obsolete surely it didn't take 200 years? And it must have enjoyed a very short favour, since the backstaff was made obsolete in the 18thC by the Campbell sextant. Either way, since your original statement was that astrolabes "were never used aboard a vessel" your challenge should include astrolabes of any period. In fact, the very fact that both you and I have used wooden astrolabes aboard vessels actually makes your original statement wrong. If Pete Straw has some information about 19th century wooden astrolabes then of course it's valid to the discussion!

I'd be interested in seeing Pete's 19th century astrolabe, but after that it pretty much seems to me that we've exhausted the information available at present. Cap'n Enigma has given us a run down of his experiences and has given us a quote showing...well, I'm not quite sure what it shows... I've given a run down of my experiences, various people have contributed information about famous navigators using wooden astrolabes, and many people have engaged in heated debate about the interpretation of all that evidence. It seems to me that until anyone comes up with new information (at which time I shall gladly rejoin the fray) all we're doing is arguing and re-arguing the same points and getting nowhere.

SO, Readers of this topic. The evidence has been presented by both sides, and has been interpreted by both sides. It is up to you how you think about that evidence. I for one have no wish for endless repetetive nastiness so I'm going to step back until new information is presented. FOLKS make your own minds up. Anyone think that's unfair? Good.

[Capn_Enigma]

I wouldn't want to be accused of misquoting. The initial comment from Cap'n Enigma which sparked this furious debate was, and I quote:

Though a wooden astrolabe is nice for learning how to use it, they were never used aboard a vessel.

Please re- read my first post in this thread:

First off, I am talking mariner's astrolabes here.

Now: Which one of these words do you not understand?

Is there a reason you're so damn rude to people?

I do not suffer fools lightly. My time is much too valuable to waste it on fools.

... you've implied both that I am a liar ...

While I do not think that you are a liar - because that would call for consciuosly telling a falsehood - you are perpetrating a corruption of historic facts when you state that wooden Mariner's Astrolabes were used on ships in the 16th to 18th century period. Neither you nor that other guy were able to prove conclusively that they were used. I asked you to show me examples of wooden Mariner's Astrolabes and you were unable to comply.

I will not elaborate why I set this time frame which marks the period during which astrolabes were used on ships. This subject is too well documented in standard books like Stimson, Gunther, Fisher, Webster et al.

Just repeating that wooden Mariner's Astrolabes were used aboard ships does not make it a fact. It merely represents your opinion, nothing more.

[Fox]

I do not suffer fools lightly. My time is much too valuable to waste it on fools.

That is absolutely the least meaningful and most arrogant excuse for what are frankly atrocious manners ever invented. It is quite possible to give short, brusque replies (or not reply at all if your time is that valuable) without deliberately insulting people. Try it sometime.

Just repeating that wooden Mariner's Astrolabes were used aboard ships does not make it a fact. It merely represents your opinion, nothing more.

True, one might say the same of your arguments. However, as I said before, arguments have been advanced for both points of view. I respect other board members enough to allow them to form their own opinions based on the arguments already presented.

Now, would you care for a drink?

[Capn_Enigma]

Now, would you care for a drink? 

Always!

But, of course, dressed in style!

Down the hatch!

[Cap'n Pete Straw]

"...If you feel the need to quote me, please be so kind as to quote me properly."

I have done nothing but quote you correctly. Sadly, you are not keeping track of what you are saying, so it is terribly easy to use your contradictory statements against you. To be clear, again, you said the exact specific wording as follows:

"Though a wooden astrolabe is nice for learning how to use it, they were never used aboard a vessel."

And now I pose to you your own question: Now: Which one of these words do you not understand?

"Never"? "Never"?? You were stupid enough to boldface the word. Not once, but twice. And I tell you that you are wrong and mistaken. And I challenge you to prove this stupid statement you made. Go ahead, I dare you. You supplied one reference that proves they were used aboard ships, so now you need to provide at least two independent sources to cancel out the one you already provided (this is a respected method of historical research and documentation, an area in which you are clearly unfamiliar). I am sure you cannot, but go ahead and try.

If you wish to admit that your original statement was incorrect, or that it was a gross misstatement, then admit your error, withdraw your statement, and say what you want to say. But your original inaccurate (proved thus by no less than yourself) statement stands as is, unmodified.

"Also, I made 3 wooden astrolabes in all (2 planispheric and 1 Mariner's), using them onboard my various ships."

You fool! You used a wooden astrolabe aboard a ship -- not just one, but three! And you are stupid enough to admit this after making the unprovable claim that they were never used aboard a vessel! How are you expecting to prove your claim if you do not stop making statements that contradict it?

"You, Sir, are obviously even too ignorant to realize that there two very different types of astrolabes (Planispheric and Mariner's) and I shall not waste my time again to teach the difference to the likes of you."

Is that what I am? Is it that obvious? How many years have you studied and researched astrolabes? How many years have I done it? How much reference material do you have on the subject in your private library? How much do I have? I hear you claim that you have actually constructed some and, if this claim is true, then I applaud you for your limited experience. But how many actual original astrolabes have you seen? And in which collections around the world have you seen them? Answer these questions, squire. Answer them all. Or are you too ignorant to be able to back up more of your outrageously false claims?

Oh, there were only two types of astrolabes? They were "very different" from each other? On the subject of ignorance sir, it is I that rest my case.

"Your continuous efforts to ridicule me are thwarted by the fact that you are not even familiar with the most basic of knowledge in this area and trying to lecture others while being unladen with any knowlwdge yourself is ... foolhardy."

"Fact"? You have the audacity to use this word? You, sir, have shown no evidence that you are familiar with the definition of this word. I am not ridiculing you at all -- you have done that all by yourself.

And I suggest you re-read all these posts. It is not I who purport to lecture others ... I have simply clarified quotes that you yourself clearly did not read.

"... 16th... century ... before that time, Mariner's Astrolabes were not "invented"..."

Reference? Show me a reference on this one. In the sake of discretion and manners you should zip it up, as your ignorance is showing, and I am embarrassed for you.

"... you, Sir, are not a conversational partner for me."

I apologize most wholeheartedly! Clearly you do not only spout untruths, as this is a purely accurate truthful statement! I agree with you 100%! I need prove nothing to you; you have backed up nothing you have said, and only continue to make ridiculous claims that you cannot prove.

This converstion is completely, absolutely and uterly ended here and now. I bid you Good Day.

[Capt DaggezEber]

These astronomical (or planispheric) astrolabes are especially beautiful.

Can you take it apart and change the tablet within to another latitude or is it fixed to one latitude?

Sadly I be a layman to much of this discussion. I'm trying to learn. So please forgive me ignorance. I believe it IS ment to come apart as the nut on the back is removable allowing the parts to disasimble. However I have not done this as it is largely a decoration on me cross-belt.

[Capn_Enigma]

I have to admit that I envy you. I have been looking for a keychain (it is a keychain, right?) of this kind for quite some time but I found most to be too expensive. But I keep looking...

Planispheric astrolabes are usually meant to be dis- and reassembled according to the latitude the user is on. There are usually several so- called tablets within the round outer thing (which is called the mater). The astrolabe is usually disassembled by unscrewing / undoing the axis and removing the star overlay (called the rete, Latin for "net" because of its cobweb - like appearance). After that, the tablets can be taken out of the mater, and the appropriate tablet reinserted on top.

To clarify this, here's a disassembled astrolabe that I have built:

Upper left: Rete

Below left: Assorted tablets

Upper right: Mater

Middle right: Rule and alidade

Below right: Axis pin, washer and wedge (equuleus)

[Capn_Enigma]

Mr Straw:

You fool! You used a wooden astrolabe aboard a ship -- not just one, but three!

Well, I guess you caught me there!

"You, Sir, are obviously even too ignorant to realize that there two very different types of astrolabes (Planispheric and Mariner's) and I shall not waste my time again to teach the difference to the likes of you."

Is that what I am? Is it that obvious? How many years have you studied and researched astrolabes? How many years have I done it? How much reference material do you have on the subject in your private library? How much do I have? I hear you claim that you have actually constructed some and, if this claim is true, then I applaud you for your limited experience. But how many actual original astrolabes have you seen? And in which collections around the world have you seen them?

To answer your questions in order:

Yes - definitely yes -15 - 0 - 10 to 15 books, several thousand copied pages, printouts, treatises etc, a dozen computer programs that I have written for calculating astrolabe construction - 0 - Thank you, but limited? I don't think so - about 20 - Museum für Kunst und Gewerbe (Hamburg), Stadtmuseum Frankfurt, Germanisches Nationalmuseum Nürnberg, Deutsches Museum (München), Conservatoire National des Arts et Metiers (Paris).

You?

[Captain Jacob Badger]

And?........still don't disprove that 'wooden' astrolabes ...'were' used aboard........but hey...wot do I know......I rely on gps.....