As I understand it, using the interactive image on the curve calculator, the "eye level" line would be the perpendicular level line from earth's radius. Shouldn't the eye level line be 12 ft above the horizon?
The calculator gives the dip in degrees, it's not a lot from 6 feet - very difficult to spot at all. The eye level IS 12 ft above the ocean horizon (at the horizon, 3 miles away), which in that image is exactly the same as being at the horizon or 6 feet above it, or 12 feet below it.The the only measurable and relevant way to measure the dip of the horizon is with degrees.
You can work it out perhaps more intuitively as arctan(12 feet/3 miles) = arctan(12/3/5280) in degrees = 0.043 degrees. It's a very long skinny triangle.It's arcsin(a/(r+h)), or arcsin(15838.00/(20903520.00+6.00)) = 0.00075767 radians, *180/PI = 0.04341137 degrees
I'd recommend drawing a diagram with suitable notation to explain what you have so far expressed in words. It might become clearer to you.Unless I'm really missing something, which is quite possible.
How can one accurately measure the angle of dip without an accurate third point for reference?
A vintage theodolite used in geodetic surveying. The wheels are marked in degrees. Is this what you would consider the third point for reference?
I'm just the most amateur of amateur astronomers and only know the basics.
I think where you're getting confused is in scale. A brick wall that's out of level by 18 inches would be a horrible bit of work.
But think about scale. Eighteen inches across three miles is a tiny error in proportion.
Just wondering, let's say the level is out 2mm in a km. How far off would that be in three miles or about 4.7km? I would guess that just as drop increases per mile that the inaccuracy of the level would increase also.
I doubt one can just multiply 4.7 by 2, surely the further one goes the error increases.
You've got to stop thinking as a builder, and start thinking as a navigator/astronomer/geodesist.
FE Believers tend to have a one-mental-step thought process. Seeing should be believing, according to their "Zetetic" philosophy:
The questions you pursue in this post are all based on this statement, above, "...it looks like the level is roughly 6 ft above sea level."Also, in the Malibu water level video it looks like the level is roughly 6 ft above sea level.
Separate topic, separate post!Just wondering, what did you expect to see? If you were at 14,500 ft looking out over land that's 5,000 ft, wouldn't one expect the level to be in the clouds?
This video shot at Malibu and Mt. Wilson (CA) is taken from a Metabunk member's much longer video shown here. That thread has been exiled to the "Rambles" sub-forum so it doesn't appear on the main index page.Here's a video of someone using the liquid level at various elevations (sea level, 1200 feet, and 5600 feet):
On the plus side, it shows exactly what we would expect - that the level of the liquid is somewhat higher than the horizon:
On the negative, he neither used a tripod for the camera, nor a stable base/frame for his level.
There was something else up there to learn that I had no clue about beforehand:
Even experienced surveyors, scientists and geologists are prone to let their sense of pride interfere with accuracy. And I can tell you why I say that, but maybe nobody is reading this, so I'll wait for someone to ask. Plus I don't want to be scolded for being "off topic." Maybe there is another thread somewhere that discusses this subject. I can't find one.
Flat earth Youtuber Antonio Subirats has devised a method for disproving or proving the globe using the horizon dip or lack thereof. The idea is to point one end of a tube at the horizon and see where the other end points
See attached model using CAD and according to CAD there will be a 18KM drop at aprox 30K feet (9KM), this will be seen easily I imagine.
There's plenty of theodolite apps that have you the angle. Just point them at the horizon. The problem is ensuring they are calibrated.If anyone has an idea of how I can actually measure the drop, I'm open to that for sure. Maybe need some sort of angle differential measurement?