gravity hill straws lane woodend

Apparently this sort of hill is fairly common around the world. Many years ago I went to Straws Lane near Macedon and a plastic bottle full of water convinced me it was rolling uphill.

Here's an "experiment" with a sense of humour

Wikipedia says this uphill stuff is an illusion.

[I understand the third point of reference /triangulation bizzo, but a hill is a hill is a hill. ]

The slope of gravity hills is an optical illusion, although sites are often accompanied by claims that magnetic or even supernatural forces are at work.

The most important factor contributing to the illusion is a completely or mostly obstructed horizon; without a horizon, judging the slope of a surface is difficult as a reliable reference is missing. Objects one would normally assume to be more-or-less perpendicular to the ground (such as trees) may actually be leaning, offsetting the visual reference.

The Wikipedia article then goes on about some kind of physics experiment and an Ames Room – way over my head.

There is also a reference in Wikipedia to what cyclists call a “false flat”.

A low-gradient climb, usually occurring partway up a steeper climb. So-called because while it may look deceptively flat and easy (especially after the steep climb preceding it), it is still a climb.

This sort of made sense to me til I tried to plot it like a simple graph line. Now I get it even less.

It all makes me feel as stupid as Why is it so?’s professor Julius Sumner Miller.