Adam Walker, a natural philosopher, performing scientific experiments. Coloured etching after J. Gillray, 1796. https://www.rawpixel.com/image/13951440/image-cartoon-face-personFree Image from public domain licenseAdam Walker, a natural philosopher, performing scientific experiments. Coloured etching after J. Gillray, 1796. https://www.rawpixel.com/image/13969726/image-cartoon-face-frameFree Image from public domain license