h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I'll do that.

I was also wondering whether, under 'Ancient Lenses'to make reference to Robert Tempe's The Crystal Sun'?BIGAL

I really like the new intro! Much more informative

The repetition of 'recognised' is awkward here >>showing up details was well recognised, as can be recognised from a reference in Seneca.<< Maybe try '...recognised, as is noted in a Seneca reference.' Also, the parenthetical information would work nicely as a footnote.

If you like you can block quote the excerpt from Comedy of the Clouds by surrounding it with and .

Need a space here - >> Robert Hooke (1605-1703)improved <<

Latin words should be italicised - Lens culinaris

In ancient lenses segment, since the discovery was recent and the lenses are presumably still in existence, it's better to describe them in present tense: 'shapes closely match' and 'are comparable to'.

Double quotes should be single quotes - "Ancient Inventions" should be 'Ancient Inventions'.

Heraklion Museum of ancient Cretan civilization - Ancient and Civilisation should be capitalised, and civilisation should probably be spelled with an 's'.

This is practically there! Good work!

Good eyesight, Miloso. I've made those changes and added a smalkl bit suggesting people look at 'The Cystal Sun'. It seems, from the extensive references that Temple gives that this is more than 'metascience'.BIGAL

I am troubled by "...a marvel to the Romans that cold water should be able to burn!" because it is ambiguous, and easily misinterpreted as saying that the water itself is in flames, rather than what I think you are asserting: that the cold water is *causing* a burn (cf. a boiling kettle will burn you without being on fire)

The ambiguity could be removed if you added 'something' to the end of the sentence ie "...able to burn something!"

Also I was a little thrown by use of the adjective 'spherical' which I usually take to mean "having the shape of a sphere or ball" being used to mean "having the shape of part of a sphere" - a spherical cap http://mathworld.wolfram.com/SphericalCap.html This may just be my unfamiliarity with optical terminology where I guess 'spherical' is frequently used to indicate the curvature of parts of spheres.

Pimms

Thanks Pimms. I've removed the ambiguity about burning.

I'm also unfamiliar with the terminology used in optics, but my understanding is that a spherical lens is a lens that has at least one surface forming an arc that is part of a sphere.

A 'cap' seems to be a much more substantial portion of the sphere e.g. a hemisphere.

Perhaps someone else could corroborate this for me?

BIGAL

Great job overall. I like the updates on the section on optical glasses. This is much clearer (pun intended).

I'd still take out the aspheric lens bit however. Have a look at the Melles Griot on line catalog glossary entry on "aspheric lens"
(www.mellesgriot.com then go to glossary) or this link: http://shop.mellesgriot.com/products/glossary/wordlist/shopglossarydetails.asp?wID=94

I've removed the reference to aspheric lenses. I nearly got myself into even deeper water by introducing the term 'toric lenses'. One reference said categorically that this was another term for spherical lenses whilst orther references seemed to imply that it was a term for elliptical lenses. Hence decided not to mention this as all!

BIGAL

An interesting article. I can see that to amplify you would need to add considerably more, but there does seem a bit of a dearth of 'modern history'.

The first sentence is not quite correct. Lenses can be other materials. The essential characteristics are that the material must be transparent and that one or both surfaces are curved such as to converge or diverge the light passing through the substance.

'The lens surface (either side) of spectacles can be spherical or cylindrical' - or a combination of both (toric). 'Throughout the surface' sounds wrong - perhaps it should be 'A spherical surface has a uniform curvature'?

I think you need another heading near the end which indicates that you are now talking about recent developments.
You might want to add that plastic lenses are also thicker than the equivalent power glass lens.

for that teaswill; I've tended to those points. Can't understand how I hadn't noticed the problem with the first sentence myself. It must have been because it was the first thing I put down to 'not have a blank sheet', and I never got around to improving it.

As I said at the top, my sole intention in writing this article was to show that optical quality lenses could have been avauilable during the 13th-15th Centuries to create the image on the Shroud of Turin in a camera obscura. I had hoped I would find such an article that I could refer to in the various Guide entries on telescopes, microscopes etc, but there wasn't.

Nevertheless, I have worried about the title; perhaps it should be 'A Brief Early History of Optical lenses. This would allow space for s'one else to write the 'Later History....'


BIGAL

A view of early optical lenses?

Have you looked at David Hockney's theory? Google provides a few links including:

http://www.brianmicklethwait.com/culture/001426.shtml

yES, THANKS FOR THAT teaswill. I wasn't aware of that particular article, although I had seen the TV programme about Hockney/cameras obscura. I haven't mentioned him in my article (on C.O'S) simply because (as I explained elsewhere) he was preaching to the converted. IU thought it was generally accepted that several of the Grand Masters had used a C.O. in their work.
BIGAL

Are you happy with this as it is BigAl?

I was looking it over and wondered whether a first header, just after the short introduction to the subject of the entry, might be worthwhile - something like "From Burning Glasses to Microscopes"

It might be worth adding in the intro that 'traditionally the history of advances in lenses has focussed () on C16th to C18th Europe, particularly in Italy and the Netherlands, but there have been some anomalous archeological discoveries that contradict this simplistic view.' This would assist in making the structure of the entry comprehensible.

Also the Ancient Lenses header could be amended from ALL CAPS

Pimms

Hallo Pimms,

Yes, I like all the ideas you've suggested. I'' put you down as a co-author.

BIGAL

I've made those mods. Pimms. Also took the opportunity to do the paragraphing correctly and to put some more of the quotes into 'blockquotes'

I put you down as co-author but, for some reason, it now looka as though you researched and wrote the article, and I edited it.

Does this come out right during sub-editing? (Thre same thing happened in reverse when another Researcher put me down as a co-author)

BIGAL

I'm not sure I've made much of a contribution to the researching and writing. As Gnomon first pointed out to me adding co-researchers to your entries can give a misleading impression. While it is in PR you will be listed as Editor, and other co-researchers as researcher/writers. When it is recommended the copy that goes to sub-editor will become listed with the sub (or sometimes 'h2g2 Editors') as the editor, and everyone else is listed as researcher/writers *in U number order* - ie people who have been on h2g2 longer will be listed first. This can make it seem as if the *real* writer only assisted.

Anyway I like the changes made (well I would, wouldn't I?) The whole entry still seems a bit disjointed in places, with some points not being followed up eg

"The lens surface of spectacles can be either spherical or cylindrical." ...er yes? The significance of this is? possibly worth adding "ie with a regular curvature that relates to a centre of curvature or an axis of curvature respectively. This means that the lens focusses light to a point or line."


I also think some of the links don't need to be referred to so explicitly (to find out more click on...etc)

Just a couple of suggetions

Pimms

Ahn...Not here, please! I can't believe this position of author *crap* is already creeping into hootoo! So what!?!?! (Do you know the struggle over the 'who get's the asterisk'? I think this is absolutely horrible.) In my opinion the decision is up to Bigal (if you, PM, don't object of course). He knows what he's done, you know what you have contributed. The rest is of no importance.

UNK!

HELL

PS: If need be, one could always search for this PR thread and find the real author who did all the hard work. The asterisk guy. Grmpf!

... And while we're at it. All this 'solo author' fuzz is (IMHO) also just *crap*. The threshold for including people as co-authors on Entries is kept artificially high because of this. People just don't give credits where credits are due so easily.


But then again, maybe this is just me.

Sorry... (I know the soapbox would be a better place to put this - but now it's too late folks )

HELL

Hi Pimms

for that. (It's actually quite interesting to me at this stage in my h2g2 'career', Hell, for me to know what the convention is for indicating authorship).

I'll have another look at what I wrote about sherical and cylindical lenses but basically, I thought that any technical discussion belonged more appropriately in a separate entry on 'spectacles'. Before anyone actually write that, the hyperlinks are there to allow those interested to follow it through.

BIGAL

I see your point Hell. On the other hand I appreciate the slightly selfish pleasure of being able to point to an entry and say "I wrote that", an achievement that shouldn't be diluted with co-author credits for everyone who spotted a typo. Yes h2g2 is a great collaborative construction, but it isn't spoilt by .

I generally wouldn't expect to give or receive co-author credit for minor amendments made in PR. For one thing it makes it tricky for scouts to nurture an entry to where they are happy to recommend it, and find themselves in the situation where they may have qualms picking it because the author has listed them as a co-researcher

IMHO (I've got some too ) co-researcher credits are most effectively used for entries discussed and written by more than one researcher before they enter PR, or where a clear section of the entry (not just a sentence) owes its inclusion to the research of one of the co-researchers.

Anyway BigAl you now know the score with co-authoring, and personally I'm happy with a 'thanks for the help' posting if my suggestions have been helpful - if you want to remove me go ahead. As Hell says I know what I've done, and this may get picked quicker without me listed

Pimms