Discoveries and inventions of the nineteenth century (1905)
Routledge, Robert · London : G. Routledge and Sons · leaf 529
FiG. 250. … duce images in different positions, giving the appearance of a jerky rotation.The instruments sold in the shops have sometimes a thin metallic discwith the slits in it, and a series of designs printed in smaller paper discs.The paper discs may be screwed on the other disc as required, and abutton…
Inventions
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