[time-nuts] reply re Harrison's timing method - #13 in Vol 176, Issue 44 digest

[jimlux]

On 3/26/19 4:27 PM, Neville Michie wrote:
> It must be a sign of the dedication that Harrison applied to his work.
> It is not as simple as the description first appears, this is England,
> and the method presupposes that there are no clouds. It might be a week
> or two before two nights occurred, when an unclouded night was followed
> by another night within several days that was not clouded.
> Similarly, with the longitude method, stars must be visible within a
> short period of dawn or dusk, when the horizon is visible together with
> the star. Sun sights are not so difficult.

You can use an artificial horizon (historically, a pool of mercury) and 
shoot the star and its reflection, then divide by two. I've used water 
reflection in a bowl to shoot the sun and moon, but those are really 
bright. I've not tried a star. It would be really hard in an area with 
background light because you'd have trouble dark adapting.  You can 
fairly easily shoot moon and star together, though, to get an angle 
between star and moon's limb.

Maybe you could float some aluminized mylar on the water surface to help 
the reflectivity.



> GPS makes is so easy for us!

Until the batteries go dead.