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Below are two cropped views of "Johannes Hevelius's 8 inch telescope with an open work wood and wire "tube" that had a focal length of 150 feet to limit chromatic aberration." from Harvard University, Houghton Library, pga_typ_620_73_451_fig_aa (found here) the first of which I've zoomed and enhanced the contrast.

I've used these images in two other questions in Astronomy SE:

This answer provides a link to the original text and image but the discussion was published in 1673 and may be difficult to understand or paste into google translate.

However, the structure itself may be familliar to engineers. I'm getting the feeling that the series of square blocks with round holes and string or lines connecting them (presumably under tension?) have no specific optical function, and are purley part of a system to keep the long "telescope tube" stiff.

Is this combination of blocks and lines a recognizable implementation of some named structure or technique?


enter image description here

enter image description here

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    $\begingroup$ An interesting way to make a telescope. It shows how ingenious humans have & can be, irrespective of what era they lived in. $\endgroup$
    – Fred
    Commented Feb 15, 2019 at 14:00

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Lateral stiffness is from the diamond stays and notched spreaders. The weight is distributed along the beam using a running "crow's foot" arrangement. The square blocks and holes are presumably there to aid in telling the rigger what they need to do to keep it all straight and true.

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  • $\begingroup$ Thanks for your answer! It must have been quite a group effort to set up and use. $\endgroup$
    – uhoh
    Commented Apr 6, 2019 at 23:54

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