What is it?

Discussion in 'Off-Topic' started by scifan57, May 21, 2012.

  1. Richard Brown

    Richard Brown Super Moderator Staff Member

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    You are on the right track. It is small used indoors and measures distance.

    Sent from my iPad 1 using iPF - Greetings
     
  2. scifan57

    scifan57 Super Moderator Staff Member

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    An indoor distance measuring wheel?
     
  3. Richard Brown

    Richard Brown Super Moderator Staff Member

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    You are closer. Try this picture.

    image-1103921090.jpg

    This shoul be enough for you to answer both questions

    Sent from my iPad 1 using iPF - Greetings
     
  4. scifan57

    scifan57 Super Moderator Staff Member

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    It's part of a drafting tool set.
    It's used to measure distances on plans and blueprints.Is it calibrated to give a readout in actual distances when rolled across a scale plan?
     
  5. KevinJS

    KevinJS Super Moderator Staff Member

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    Richard PMed me the answer. That is exactly what it does. Any idea what it is called?

    Sent from my iPad 4 HD mini
     
  6. scifan57

    scifan57 Super Moderator Staff Member

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    How about a map wheel.
     
  7. Richard Brown

    Richard Brown Super Moderator Staff Member

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    Sort of, but there is a specific name.

    What do you use to take measurements such as speed, or mileage? That will give the last 5 letters of the name - the class of instrument.

    Sent from my iPad 1 using iPF - Greetings
     
  8. scifan57

    scifan57 Super Moderator Staff Member

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    You do realize that the original challenge didn't ask for the exact name of the instrument,don't you.

    Richard Brown said:

    "OK, I was hoping to answer a challenge before posting. The challenges have proved well. Very challenging!

    Here's mine.

    What is this part of?

    What is it used for?

    As a bonus, but not an essential question, how is it used?



    image-1231768316.jpg



    The original image is definitely out of copyright.

    Sent from my iPad 1 using iPF - Greetings"
     
    Last edited: May 24, 2012
  9. Richard Brown

    Richard Brown Super Moderator Staff Member

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    Fair enough, Scifan. You have the challenge now. The instrument is called an opisometer.

    Sent from my iPad 1 using iPF - Greetings
     
  10. AdmiralAdama

    AdmiralAdama Super Moderator Staff Member

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    Need to reattach the pic scifan. I can't read it.
    AA
     
  11. scifan57

    scifan57 Super Moderator Staff Member

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    I've looked and I discovered that the terms map wheel,map meter and opisometer are used interchangeably for the same device.
     
  12. scifan57

    scifan57 Super Moderator Staff Member

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    Here's one for everyone.
    What are we looking at?What was it used for?Who is credited with the invention of the first of these devices?

    image-1742991968.jpg

    image-1614027579.jpgWhat is the cone shaped piece in the second photo and what is it's purpose?
     
    Last edited: May 24, 2012
  13. scifan57

    scifan57 Super Moderator Staff Member

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    Here's another photo.

    image-3632262419.jpg
     
  14. twerppoet

    twerppoet iPad Legend

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    It looks like the mechanism for an early marine chronometer. These chronometers had to be certified, for accuracy, and were used for naval navigation. Knowing the exact time is crucial for determining longitude in when navigating using a sextant in celestial navigation. It was the invention, a lifetime of work, by John Harrison that allowed an era of exploration and navigation to begin.

    I'm less sure of the first, since I haven't found any good sources. The cone shaped pice is called the 'schnecke' in German, which translates to 'snail'. I've no idea if that is what it's actually called in English.

    In the diagram I saw there is a chain that wraps around the snail and the geared drum (shown in the last picture). Both the gear and the snail are a continuous spiral (thus the snail) rather than distinct rings. My guess is that it is used to compensate for variable strength (torque) of the spring as it unwinds.

    File:L-Cronometer.png - Wikipedia, the free encyclopedia


    Note: I'm out of the house for a bit, maybe an hour. Be back soon to see if I need to post a challenge.
     
  15. scifan57

    scifan57 Super Moderator Staff Member

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    You've solved the mystery.The photos are of an antique Marine Chronometer.
    The chronometer in the pictures is about 120 years old,but virtually identical Chronometers are still made today,mainly for the collectors market.
    The "cone" shaped piece is called the Fusee.
    Here are more pictures.
    An excellent resource to read is "The Marine Chronometer" by Rupert Gould,who restored the Harrison Chronometers,H-1 to H-4.
    There is an excellent TV miniseries about the problem of finding longitude at sea.It's called"longitude".


    image-4216761849.jpg



    image-2459068737.jpg



    image-3594587539.jpg



    image-2989596789.jpgThe hands are made of gold and the end stones of the balance wheel are diamond.
    Your turn to post the next challenge.
     
    Last edited: May 24, 2012

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