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    Re: Bubble sextant construction
    From: Robert Eno
    Date: 2013 Mar 21, 20:26 -0400
    
    Slight correction to my last:

    Randall asked: Was it with application of pressure or by addding-subtracting volume of fluid?

    Robert responded:

    I can tell you that this is definately the case for the C.Plath (having fixed a lot of these babies over the years) and I do believe it is the same for the RAE MK IX: pressure was applied or relaxed to push fluid in and out of the bubble chamber.
    ---------------
     
     
    I will add a bit to this: on most bubble sextants (I have not used them all), in order to reduce the size of the bubble, or remove it altogether, you have to tilt the sextant such that the bubble abuts against a port (sometimes marked with an arrow on the chamber window ) in the chamber, then turn the adjusting knob. This essentially sucks out the air, while at the same time, fluid is introduced into the bubble chamber via a different port.
     
    When you look at the way these things were made, you cannot help but admire the ingenuity and workmanship that went into these wonderful instruments.
     
    Robert
       
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