This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
PSM Old Mathematical calculation . Old style mathematical calculation archive org Popular Science Monthly Volume author PDold Extracted image from book to grayscale cropped whitespace ineuw archive org Popular Science Monthly Volume Popular Science Monthly illustrations Mathematical education
Page 2023 Free-images.com. All images are Public Domain