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Author Topic: How Did the Castaways Build Fires  (Read 55851 times)

Tim Collins

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Re: How Did the Castaways Build Fires
« Reply #15 on: January 06, 2011, 07:10:22 AM »

Gallagher's confident identification of part of an inverting eyepiece that he supposedly never saw has always bothered me. ...

To me the term "inverting eyepiece" suggests a knowledge of a certain specialized jargon let alone that it specifically came from a sextant (I'm sure there are other instruments that use such a thing). Has anybody given any thought as to whether or not such a term would likely have even been a part of Galagher's vocabulary? And if not where would he have come by such a term?

t
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Ric Gillespie

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Re: How Did the Castaways Build Fires
« Reply #16 on: January 06, 2011, 07:30:53 AM »

Gallagher owned a sextant himself.
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Martin X. Moleski, SJ

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Re: How Did the Castaways Build Fires
« Reply #17 on: January 06, 2011, 07:35:30 AM »

Gallagher owned a sextant himself.

OK.  Here's how Gallagher might identify the missing piece without seeing it: show his sextant to the work party and ask them to point out the piece that most closely resembles the piece that went walkabout.
LTM,

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Ric Gillespie

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Re: How Did the Castaways Build Fires
« Reply #18 on: January 06, 2011, 07:36:33 AM »

That could work.
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Don Dollinger

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Re: How Did the Castaways Build Fires
« Reply #19 on: January 06, 2011, 11:00:14 AM »

Quote
We've done some experiments using the lens of an inverting eyepiece. It's basically a little magnifying glass. I can burn my hand with it on a sunny day right here in Delaware.

Just a thought, but didn't her inventory say she had a pair of binoculars?  I know that the removable eyepiece of my Dad's Bausch and Lomb binoculars used to fry ants in a fine fashion (until Dad found out we took his binoculars apart).  Although a pair have not been found by TIGHAR something like that found by someone at the 7 site I would think would be quickly snatched up and not left there to be found.  Although I would suppose that a sextant eyepiece would be similar.

You would think that most people in that situation (figuring what to save from the Electra) would highly consider binoculars to be able to see ships that may be searching for you.
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Mona Kendrick

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Re: How Did the Castaways Build Fires
« Reply #20 on: January 06, 2011, 11:30:18 AM »

You would think that most people in that situation (figuring what to save from the Electra) would highly consider binoculars to be able to see ships that may be searching for you.
[/quote]



It may depend on how much of their gear AE & FN were able to unload before the plane went over the edge of the reef.

LTM,
Mona
« Last Edit: January 06, 2011, 11:39:34 AM by Mona Kendrick »
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Ric Gillespie

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Re: How Did the Castaways Build Fires
« Reply #21 on: January 06, 2011, 11:50:20 AM »

Just a thought, but didn't her inventory say she had a pair of binoculars?

Remember that the only inventory we have is from after the Luke Field wreck.  We don't know what was aboard the plane for the Lae/Howland flight over three months later.  That said, I would want to have binoculars along on a flight that relied upon spotting a small island.
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Mark Petersen

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Re: How Did the Castaways Build Fires
« Reply #22 on: January 06, 2011, 02:19:53 PM »

To me the term "inverting eyepiece" suggests a knowledge of a certain specialized jargon let alone that it specifically came from a sextant (I'm sure there are other instruments that use such a thing). Has anybody given any thought as to whether or not such a term would likely have even been a part of Galagher's vocabulary? And if not where would he have come by such a term?

So if Gallagher had his own Sextant as Ric has said, then it's almost a given that he would know what this term means.  Even if Gallagher didn't own a sextant, I would think that he would still have been familiar with the term, because refractor telescope designs are so common  (even more so back then) and inverting eyepieces are part of the design. It wouldn't surprise me if Gallagher also had a "spyglass" telescope with a collapsible/telescoping tube as those were very common back then. 

It's also interesting that Gallagher knew enough about optical design to refer to it as an "inverting eyepiece" rather than an "erecting eyepiece".  I'm not an optical engineer, but from what I understand, an Inverting eyepiece refers to the most common eyepiece type that is used with refractor telescopes and I think they are also used with binoculars, microscopes and possibly sextants.  With refractor telescopes the image is inverted top to bottom as the norm which is where the inverting eyepiece gets it's name.   It requires a specialized prism (as is the case with binoculars) or a specialized lens (such as a Barlow) to reverse the image and these are referred to as an "erecting prism",  or "erecting eyepiece" and they are commonly used in combination with the inverting eyepiece.  Erecting eyepieces have the potential to degrade the image so it's common practice (especially with astronomers) to use only the inverting eyepiece and thereby live with the reversed up and down orientation. 

With that in mind has anyone considered the possibility that the eyepiece came from a different source from the sextant, say from binoculars?  Does Gallagher specifically say that the eyepiece came from a sextant?  Also does anyone know if sextants used only inverting eyepieces or did they sometimes also use erecting eyepieces as well?


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Don Dollinger

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Re: How Did the Castaways Build Fires
« Reply #23 on: January 06, 2011, 02:43:52 PM »

Quote
I am curious to know how the castaways would have built fires?  Perhaps they had some matches or a cigarette lighter

Reread the Luke Field Inventory and one would think that some items that were prepackaged would remain the same on the second flight.  Item #67 is a canvas bag of assorted items with one of those being a "waterproof match container with matches".

I also listed that she had a signal pistol but I distinctly remember reading somewhere that she had jettisoned that prior to or at Lae prior to takeoff for Howland along with a water making machine and a hand crank generator for the radio.

That is what is so frustrating it seems that some of the very important items that would have aided in survival and/or rescue were uncermoniously dumped along the route.  It would make one think that she was cognizant of the importance of these items as someone had the foresight to think about the unthinkable (crashing enroute) and had purposely packed those items.

LTM,
Don
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Ric Gillespie

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Re: How Did the Castaways Build Fires
« Reply #24 on: January 06, 2011, 05:27:41 PM »

With that in mind has anyone considered the possibility that the eyepiece came from a different source from the sextant, say from binoculars?  Does Gallagher specifically say that the eyepiece came from a sextant?

You can read exactly what Gallagher said.

  Also does anyone know if sextants used only inverting eyepieces or did they sometimes also use erecting eyepieces as well?

I don't know but I do know that an inverting eyepiece is a standard sextant accessory for use in situations where you may want to move the observed celestial body up, rather than down, to the horizon.


[/quote]
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Mark Petersen

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Re: How Did the Castaways Build Fires
« Reply #25 on: January 06, 2011, 07:40:34 PM »

[
You can read exactly what Gallagher said.

Thanks Ric.  I'm not seeing mention of an eyepiece in the Gallagher exchange though.  I do see the exchange here though:
http://tighar.org/wiki/Inverting_eye_piece_found_on_Nikumaroro

  Also does anyone know if sextants used only inverting eyepieces or did they sometimes also use erecting eyepieces as well?

I don't know but I do know that an inverting eyepiece is a standard sextant accessory for use in situations where you may want to move the observed celestial body up, rather than down, to the horizon.

I think we've been using the term incorrectly.  I know nothing about Sextants, but from my knowledge of the terminology in astronomy, the term is somewhat of a misnomer.  With a refracting optical design the objective lens (the lens at the front of the telescope) inverts the image.  The basic eyepiece used with a refracting telescope does not correct this inversion but is unfortunately given the name "inverting eyepiece".  If a person wants to correct the inverted image an accessory eyepiece or prism is needed, but this eyepiece is called an erecting eyepiece.  So saying that it's an inverting eyepiece is equivalent to saying that it's a standard eyepiece rather than an accessory.

From the link above what Ross Devitt is describing is actually an erecting eyepiece rather than a standard inverting eyepiece. 
"An inverting eyepiece would be at least an inch or so of metal & glass. The eyepiece is used to flip the sextant image so it is more 'natural' to look at (a sextant as you know will show the image upside down). An experienced navigator probably wouldn't bother using it" (Ross Devitt, December 14, 1999 Forum).

I think Ross has the terms mixed up, but he is right that an experienced navigator probably wouldn't bother using an erecting eyepiece because it's well know that erecting eyepieces use more optical elements and degrade the image.  So what Gallagher probably found was the standard eyepiece that came with the sextant.

This probably has little relevance with the FN/AE disappearance, but it is good to know the differences between the eyepiece and what it is that Gallagher actually found. 

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Martin X. Moleski, SJ

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Re: How Did the Castaways Build Fires
« Reply #26 on: January 06, 2011, 08:30:19 PM »

I also listed that she had a signal pistol but I distinctly remember reading somewhere that she had jettisoned that prior to or at Lae prior to takeoff for Howland along with a water making machine and a hand crank generator for the radio.

See the Survival Equipment category for details.
LTM,

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Thom Boughton

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Re: How Did the Castaways Build Fires
« Reply #27 on: January 07, 2011, 12:26:22 AM »

Gallagher owned a sextant himself.

I've forgotten whether it's mentioned in the inventory of Gallaghers' effects, did he have his sextant with him on the island?

Possibly, for whatever reason, he himself snagged this one for use on his own sextant?

Merely an idle SWAG of a thought.



....TB
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Ric Gillespie

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Re: How Did the Castaways Build Fires
« Reply #28 on: January 07, 2011, 05:35:59 AM »

I've forgotten whether it's mentioned in the inventory of Gallaghers' effects, did he have his sextant with him on the island?

Yes
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Don Dollinger

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Re: How Did the Castaways Build Fires
« Reply #29 on: January 07, 2011, 09:49:31 AM »

Quote
See the Survival Equipment category for details.

Thank you very much sir, I have digested so much information on AE and FN that I have a hard time remembering from twixt it came.

LTM,

Don
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