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    Re: The development of bubble sextants
    From: Gary LaPook
    Date: 2009 Aug 15, 12:59 +0200

    Having fired many artillery projectiles over many miles of the earth's 
    surface I am familiar with coriolis. I can assure that once the 
    projectile leaves the tube that it flies in a straight line though space 
    but for an observer on earth, say an enemy platoon, it appears to curve 
    to the right. This is because the earth is turning under the path of the 
    projectile so we had to use tables to allow for this "Coriolis" and 
    ended up pointing the guns to the left of the target so the target would 
    rotate to the place that the projectile was aimed and they both arrived 
    at the same point at the same time.
    Coriolis is a fictitious force use to explain the perceived curve of the 
    flight path as observed by an observer on earth of other rotating frame 
    of reference. See:
    douglas.denny@btopenworld.com wrote:
    > Dear Gary,
    > Coriolis is a very real acceleration. It is not fictional at all.
    > The sextant (and person ) is being carried through space in a curved motion 
    by the Earth itself, and the acceleration due to curved motion is real 
    enough, just the same as if you are in the big Millenium Ferris Wheel in 
    London, or in a fairground 'Skyboat' device whizzing around in circular 
    > Coriolis just happens to be a small quantity - though relevant in 
    calculation if you are in a jet moving at around 400 knots.
    > I have a theodolite made by British Aerospace with a North seeking gyro 
    built in which 'feels' the acceleration right enough to provide North to 
    within a few second of arc.
    > Coriolis can be allowed for because the motion of the Earth is 'constant' so 
    the parameters can be calculated for the direction of travel and Latitude, 
    the main components affecting the apparent local gravitational field due to 
    > Douglas Denny.
    > Chichester. England.
    > >
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