Smyth's parallactic ladder mount, details of the frame. This device was devised by the British optician and instrument maker George Dolland (1774-1852) and presented to the British astronomer William Henry Smyth (1788-1865). Its function was to act as an equatorial mount for portable telescopes, and to be cheaper and easier to construct than fixed mounts. The telescope would be moved by hand in the cradle, rather than moved by machinery. Artwork from 'A Handbook of Descriptive and Practical Astronomy' (1890, 4th edition, volume II) by British author George Frederick Chambers (1841â1915).
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