Foucault pendulum greyscale background, vintage image. Remixed by rawpixel. https://www.rawpixel.com/image/9825713/image-background-art-vintageView licenseSjabloon met vlinders en spiralen (1800 - 1909) by anonymous https://www.rawpixel.com/image/13735585/sjabloon-met-vlinders-spiralen-1800-1909-anonymousFree Image from public domain license