Sunshine Recorder

This is a Campbell-Stokes sunshine recorder. Using this device weather stations around the world have recorded the time and duration of sunlight at hundreds of locations for well over a century. Investigators can reference this treasure trove of data to map long-term weather trends, or merely to check if the sun was out at 10AM on April 3, 1921, in Glasgow, Scotland (which it probably wasn't).

Here's how it works: A clamp holds a glass or resin orb and a hemi-spherical bowl centered on that orb. The bowl has grooves that hold a strip of paper such that sunlight passing through the orb reaches its focal point at the paper, scorching or burning it. As the Earth rotates, the apparent movement of the sun draws this focal point in a line across the strip of paper. By measuring the length of the scorched line, you can add up the hours of sunlight in a given day. You can also tell when the sun was out and when it wasn't. Ideally, you screw it into a rock or building and leave it there for