The Philosophical magazine; a journal of theoretical, experimental and applied physics
A long-running British scientific periodical begun in London in 1798 and later issued by Taylor & Francis, carrying papers on theoretical, experimental and applied physics for researchers and instrument makers. The plate shown gives two numbered figures of rotating discs in flat black, grey and white — pie sectors with lettered edge points and an opposed pair of white bowtie wedges on a solid black circle — usable as high-contrast geometric marks, spin diagrams or optical-illusion motifs.
