https://creativecommons.org/publicdomain/zero/1.0/https://www.rawpixel.com/image/13984391![Hermann Ludwig Ferdinand von Helmholtz. Stipple engraving by C. H. Jeens, 1871.](https://images.rawpixel.com/image_social_portrait/cHJpdmF0ZS9sci9pbWFnZXMvd2Vic2l0ZS8yMDI0LTAyL2xyL3djZnBqZms3cWQtaW1hZ2UuanBn.jpg)
![Hermann Ludwig Ferdinand von Helmholtz. Stipple engraving by C. H. Jeens, 1871.](https://images.rawpixel.com/image_social_portrait/cHJpdmF0ZS9sci9pbWFnZXMvd2Vic2l0ZS8yMDI0LTAyL2xyL3djZnBqZms3cWQtaW1hZ2UuanBn.jpg)
Hermann Ludwig Ferdinand von Helmholtz. Stipple engraving by C. H. Jeens, 1871.
Hermann Ludwig Ferdinand von Helmholtz. Stipple engraving by C. H. Jeens, 1871.
Original public domain image from Wellcome Collection
Public DomainFree CC0 image for Personal and Business use