>>o4c+(OP)
Awesome. I'd love to know more about instrument making techniques of the era -- especially for precisely calibrated analog computing applications like this. I know that by the 1890s machine tools were commercially available (e.g. Brown and Sharpe Manufacturing were incorporated in 1868 and were operating earlier[1, preface]) but presumably precision instrument makers evolved from clockmakers -- using hand tool techniques perfected much earlier. (Obligatory link to ClickSpring [2])
[1] https://archive.org/details/practicaltreati00cogoog/page/n8/...
[2] https://www.youtube.com/watch?v=dRXI9KLImC4&list=PLZioPDnFPN...