Such rails are typically made of wood and designed to be very stiff. The rail normally begins with a chin rest followed by a graduated grove extending from this point. This allows other features such as holders for perceptual stimuli, filters, apertures, mirrors and cameras to be bolted down and precisely shifted along the length of the rail.
[Work in progress] A meta-perceptual/ metaphysical rail is a simple piece of hardware that provides a linear track along which to mount mirrors apertures and other props and stimuli. They are used for simple meta-perceptual experiments. Testing the limits of visual and meta perceptual experience as well as exploring more metaphysical and somaesthetic questions of our experiences and location self in relation to the physical body. The device is less a tool of measurement, but as a device to enable introspection, working with an experienced operator.