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evaporative cooling - was saladin's ice

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  • julian wilson
    Dear Listers, great Posting about the solar cooker/cooler, Maitiú the JOAT , especial thanks from me for that.. While on this subject of coolers, and ice, -
    Message 1 of 13 , Jul 2, 2005
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      Dear Listers,
      great Posting about the solar cooker/cooler, Maitiú the JOAT , especial thanks from me for that..

      While on this subject of coolers, and ice, - would anyone care to refresh our collective memories on the subject of historical, low-tech, evaporative cooling?

      It occurs to me that - as this method apparently only needs 2 earthenware vessels, cloth, and water - we could all use it at our events - all one only needs 2 deep-walled earthenware pots or vessels, [one very much larger than the other, which fits inside it], enough water to fill the space between the two vessels, and two bits of a coarse thick unbleached cloth.

      I believe what you do is - put the smaller vessel inside the larger on some spacer blocks so that water gets underneath the inner vessel as well as all around the walls; put your dairy products into the inner vessel; wet one section of the cloth and drape it over the inner vessel so that the motuh is coeverd and the ends of the cloth drape down into the water; soak the second larger bit of cloth and drape it across the mouth of the larger vessel, covering all - and apparently evaporative cooling thensubstanitally lowers the temp. of the inner vessel well-below ambient.

      Our Companie haven't tried this way of keeping things - especially butter & cheese & wines - cool for our Noonmeals at our events yet, because we are still looking for suitable earthenware vessels.
      This method is also supposed to be as old as Roman Times; when it was said to have been described by Appius, and also by some Military Commentators when talking about the Legions' Commissary matters.
      Would any Lister who knows more care to add further enlightening comment for all of us?



      Yours in service,
      Julian Wilson,
      [aka. Messire Matthew Baker/Matthieu Besquer, Governor & Castellan of Jersey, 1486-1497: - "Si vis pacem, para bellum"]
      late-medieval Re-enactor; & Historian and Master Artisan to
      "The Companie of the Duke's Leopards",
      [the only medieval living-history Group
      in "olde" Jersey]

      ---------------------------------
      How much free photo storage do you get? Store your holiday snaps for FREE with Yahoo! Photos. Get Yahoo! Photos

      [Non-text portions of this message have been removed]
    • Maitiú the JOAT
      ... No problem. ... Really only useful in a dry climate. In theory, all wet things cool down until their temperature reaches the dew point, the temperature at
      Message 2 of 13 , Jul 3, 2005
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        Julian Wilson wrote:
        >great Posting about the solar cooker/cooler, Maitiú the JOAT , especial
        >thanks from me for that..

        No problem.

        >While on this subject of coolers, and ice, - would anyone care to refresh
        >our collective memories on the subject of historical, low-tech,
        >evaporative cooling?

        Really only useful in a dry climate. In theory, all wet things cool down
        until their temperature reaches the dew point, the temperature at which the
        water in the air becomes so saturated that it comes out to form
        condensation. The dew point is, depends on both the humidity and the
        temperature of the air. At 20° Celsius and a relative humidity of 50%, the
        dew point is at 13° Celsius, not a bad temperature for keeping fruits and
        vegetables. For more, see the chart:
        <http://www.matthewtakeda.net/evap_chart.gif>

        The Egyptians used porous clay pots fanned by slaves to cool water and wine
        by evaporation, as did the Romans. The water or wine soaks through the
        porous material to the surface, where it evaporates, cooling the contents.
        You've probably seen contemporary terracotta water coolers like this one:
        <http://www.watersavers.com/docs/waterfilter_ep_cooler_terracotta5gdispenser.shtml>

        Desert dwellers also used skin bags to cool water in much the same way. You
        may remember, if you are old enough, the use of water bags covered with
        canvas or other heavy material, by desert travelers in the last century.
        They were commonly seen hanging on cars in the southwestern US.

        > It occurs to me that - as this method apparently only needs 2
        > earthenware vessels, cloth, and water - we could all use it at our
        > events - all one only needs 2 deep-walled earthenware pots or vessels,
        > [one very much larger than the other, which fits inside it], enough water
        > to fill the space between the two vessels, and two bits of a coarse thick
        > unbleached cloth.
        >
        >I believe what you do is - put the smaller vessel inside the larger on
        >some spacer blocks so that water gets underneath the inner vessel as well
        >as all around the walls; put your dairy products into the inner vessel;
        >wet one section of the cloth and drape it over the inner vessel so that
        >the motuh is coeverd and the ends of the cloth drape down into the water;
        >soak the second larger bit of cloth and drape it across the mouth of the
        >larger vessel, covering all - and apparently evaporative cooling
        >thensubstanitally lowers the temp. of the inner vessel well-below ambient.

        This is a slightly garbled description of the pot-in-pot method of
        refrigeration, developed by Mohammed Bah Abba in 1995, for which he won a
        Rolex Award for Enterprise in 2000:
        <http://www.rolexawards.com/special-feature/inventions/abba.html>
        <http://www.rolexawards.com/journal/pdf/journal15-art3.pdf>
        <http://www.itdg.org/docs/agroprocessing/FC29_34.pdf>

        Campers through the early 1900s, when camping was still a somewhat
        heavyweight enterprise, used several methods to keep foods cool. A
        watertight box sunk partway in a stream or dug into the bank of a stream or
        pond was one. Another was a similar box buried in the ground, with gravel
        all around and fabric or pine boughs over top, all kept moist. Yet another
        was a "spring box," which was construced so that water from a spring
        entered the box at one end and exited at the other, with the food elevated
        above the water level. Yet another was a sort of hanging cupboard, with
        burlap walls, which were kept soaked by dipping the ends in a container of
        water. I'm sure that most of these solutions had much earlier origins.

        >This method is also supposed to be as old as Roman Times; when it was said
        >to have been described by Appius, and also by some Military Commentators
        >when talking about the Legions' Commissary matters.

        Although there isn't really any period information, you might also want to
        look at the History Channel's History of the Refrigerator:
        <http://www.historychannel.com/exhibits/modern/fridge.html>
        and Gizmo Highway's The History of the Refrigerator:
        <http://www.gizmohighway.com/history/refrigerator.htm>

        If you can find it, you also might be interested in looking at Camping and
        Woodcraft by Horace Kephart. They were published separately in 1916 and
        1917 by McMillan, then reissued in 1921 as a single volume. He lists
        several ways that fresh meat, fish, and fowl could be kept for considrable
        periods. I recall that one method for packing fish (without any ice) noted
        that such fish could be sent from Maine to New Orleans in August, a journey
        of at least a two or three days by rail, and arrive fresh.

        HTH

        Maitiú
      • julian wilson
        Maitiú the JOAT , thanks from me for another very informative posting. And for the URL s to educative web-pages. We shall certainly try applying the
        Message 3 of 13 , Jul 3, 2005
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          Maitiú the JOAT , thanks from me for another very informative posting. And for the URL's to educative web-pages.
          We shall certainly try applying the pot-in-pot cooling at our local Company events this summer, and see how well it works during a Summer in "olde" Jersey.
          I'd never seen the terracotta water-coolers, nor have I heard of the Rolex Awards or of Mohammed Bah Abba, before you mentioned them in your posting.
          My vague knowledge of "pot-in-pot evaporative cooling" came from an "ancient-history-buff" older cousin who served with the 8th Army in N. Africa during WW2, and was thereafter posted to Palestine for a 4 year hitch. When home on UK-long-Leave in the late 1940's, before returning to Palestine, he told me about coming across the evaporative method in use in N. Africa - I think it was during a Nile trip on one of his Leaves in Egypt. As best as I can recall, the subject came up while we were discussing ancient scientific discoveries/inventions being "rediscovered", because I was studying for my GCE exams in Physics and in Ancient History.

          Thanks again for sharing your knowledge with me'us/the List.

          God's Benison be upon you this Day, and until The Judgement.




          Yours in service,
          Julian Wilson,
          [aka. Messire Matthew Baker/Matthieu Besquer, Governor & Castellan of Jersey, 1486-1497: - "Si vis pacem, para bellum"]
          late-medieval Re-enactor; & Historian and Master Artisan to
          "The Companie of the Duke's Leopards",
          [the only medieval living-history Group
          in "olde" Jersey]

          ---------------------------------
          Yahoo! Messenger NEW - crystal clear PC to PCcalling worldwide with voicemail

          [Non-text portions of this message have been removed]
        • Joannah Hansen
          Have you tried looking in your local nursery? It springs to my mind that if you are looking for large terracotta pots in various shapes and sizes, that s where
          Message 4 of 13 , Jul 7, 2005
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            Have you tried looking in your local nursery? It springs to my mind that if you are looking for large terracotta pots in various shapes and sizes, that's where you will most likely find them.

            Joannah

            --- julian wilson <smnco37@...> wrote:
            <snip>
            Our Companie haven't tried this way of keeping things - especially butter & cheese & wines - cool for our Noonmeals at our events yet, because we are still looking for suitable earthenware vessels.
            This method is also supposed to be as old as Roman Times; when it was said to have been described by Appius, and also by some Military Commentators when talking about the Legions' Commissary matters.
            Would any Lister who knows more care to add further enlightening comment for all of us?




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          • byvordhr
            ... butter & cheese & wines - cool for our Noonmeals at our events yet, because we are still looking for suitable earthenware vessels. ... was said to have
            Message 5 of 13 , Jul 8, 2005
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              --- In Authentic_SCA@yahoogroups.com, julian wilson <smnco37@y...> wrote:
              > <snip>
              > Our Companie haven't tried this way of keeping things - especially
              butter & cheese & wines - cool for our Noonmeals at our events yet,
              because we are still looking for suitable earthenware vessels.
              > This method is also supposed to be as old as Roman Times; when it
              was said to have been described by Appius, and also by some Military
              Commentators when talking about the Legions' Commissary matters.
              > Would any Lister who knows more care to add further enlightening
              comment for all of us?

              Those terra cotta wine cooling vessels turn up at Goodwills and other
              thrift outlets with fair regularity. They are usually sized for one
              bottle of wine. One would be suitable for butter or cheese as well.

              Saeunn
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