Harris built a device called the Meniscope. It maps the gradient of an air-water interface to color. The principle is direct: a converging lens sits above the water surface, and a colored target pattern sits below. Where the surface is flat, light passes straight through and the observer sees one color. Where the surface tilts, refraction shifts the apparent position on the target, and the observer sees a different color. The gradient becomes a color. The shape of the interface becomes an image you can read by eye.
The device is low-cost and requires no electronics, no computation, no calibration beyond placing the lens. It makes visible what is normally invisible: the shape of a water surface deformed by objects, flows, surface tension, or vibration. Harris demonstrates it in workshop settings where participants can interact with the surface and immediately see the gradient field respond.
There is something important in the design philosophy. Most modern measurement instruments convert a physical quantity into a digital signal, process it, and display a representation. The Meniscope skips the entire digital chain. It uses optics to perform the measurement and optics to perform the display. The conversion from physical quantity to human-readable output happens in a single analog step: refraction. No sampling, no discretization, no reconstruction. The measurement and the visualization are the same physical process.
Every conversion step — analog to digital, spatial to spectral, physical to computational — introduces latency, noise, and a barrier between the observer and the phenomenon. When a measurement can be made legible without intermediate representation, the observer develops intuition for the quantity itself, not for the instrument's rendering of it. This matters most in education and in early-stage investigation, where the goal is not precision but comprehension — where understanding the shape of a phenomenon matters more than knowing its fourth decimal place.