I added an Appendix based on your suggestion.
http://tradidi.com/etc/fe-disappearing-ship
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That's beautiful -- even better than I was expecting!
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Your idea of making the third line dashed is brilliant.
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First off, at the far right side of the left hand boat you can see a nub or eave of the roof line in the main deck cabin sticking out to the right a quarter inch above the dashed red line, and the same roof line sticks out a quarter inch below the line. Below that is a chunk of blue sky before the apparent water surface. No such inferior image is to be found on the right hand boat.
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Moving to the left, you see two vertical blurs of white and then about 1/8th inch below the dashed red line is two white balls. Go over to the boat on the right and you see those same two white balls, looking like they're strung on a cable over the stern. So the boat on the left has a double image, with distortion in place of the white balls. No such inferior image is to be found on the right hand boat.
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Moving to the left of the white balls, there is a dark square above the red dashed line, and a hazy copy of the same black square below the red dashed line. See the boat on the right has only ONE bold, dark square, and none at all below it.
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Moving to the left again, you come to the doorway, which is much taller in the left boat than it is in the right boat. This illusion of taller height of the doorway is due to the illusion of a mirror-image below the red dashed line which makes the doorway APPEAR to be taller than it really is (see how tall it is on the boat on the right). The mirror image (inferior image) below the red dashed line obliterates what OUGHT to be there as seen on the right hand boat, because those details cannot be seen on the left hand boat due to the fact that the ocean surface occupies that space concealing the details, and the inferior image overwrites them. No such inferior image is to be found on the right hand boat.
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Proceeding past the corner to the left, the boat on the right clearly shows a series of 5 or 6 dark rectangles, probably windows, on the side of the boat's cabin. ALL of these dark rectangles are stretched out in the left hand boat
to become as tall as the doorway. Clearly on the actual boat the doorway is in fact much taller, as seen in the boat in the right hand picture, which has no inferior image.
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In the end, the actual horizon is twice as high as it first appeared on the left hand boat, showing how the boat has moved beyond the curvature of the earth at sea.
The horizon level covers half of the boat already..
When you let the same boat continue further away, the superstructure of the boat disappears entirely and the mast on top appears to stretch out before it suddenly disappears in the distance. The sudden changes are due to distortion of the inverted or inferior image, which changes quickly, appearing and disappearing in rapid flashes.
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Aspects of the inverted image are very similar to those of a mirage which appear and disappear in something akin to waves of images fading in and fading out in rapid succession. This flickering picture is very hard to show in a still image like these.
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