If you’re in the northern hemisphere, there’s a good chance it’s sunny where you are. How sunny is it? Well, our local chamber of commerce claims we have at least 360 days a year with at least partial sun. That’s pretty sunny for the Pacific Northwest!
Measuring the amount of sunshine received in a day has been around since the nineteenth century. Two surprisingly different men furthered the science. John Francis Campbell first invented a sunshine recorder in 1853. He was best known as a Gaelic linguist, author, and folklorist, traveling around Scotland to collect the old stories, but he also served as a barrister and a government official as well as a scientist. His recorder, sometimes called a heliograf, was a glass sphere set in a wooden bowl. The sunlight shining through the glass burned a line on the wood. The longer and deeper the line, the longer and stronger the light.
Perhaps physicist Sir George Gabriel Stokes wanted a bit more quantification. A talented scientist dedicated to education, he changed Campbell’s stand to metal and added a changeable card that records the line made by the light.
The result is the Campbell-Stokes Recorder, which measures the number of hours of bright sunlight in a certain period. The UK Met Office stores cards from various locations dating back to the nineteenth century, and the design is still widely used today. Hammacher Schlemmer even sells a version.
But if you’d like something more than measuring sunlight to occupy your time, you might check out my summer bonus, which I posted this week. “Master Thief” is a free, short online story set between Art and Artifice (formerly La Petite Four) and the soon-to-be-released Ballrooms and Blackmail. More on that soon. In the meantime, have some fun in the sun!