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Hello Frank,

A last cogitation about Lyons method.

I had study this week the methods of "linear tables" (Norie 1815) and Thomson,
with comparition with the method proposed by Lyons in the Nautical Almanac 1767.

I conclude that :

1) the formulas used for parralax correction was the same ;

2) Lyons proposed in NA 1767 tables for refraction correction, but not very practical ; so, Norie had proposed "linear tables", but added another correction given by table XXXV (quadratic correction).

3) in the Thompson method, the "Table XVIII" give directly the correction of refraction combined with quadratic correction.

Are you agree with me ?

Have a nice week end

Jacques

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