Probably the best example of this type of mounting applied to a refractor is that made by the elder Cooke of York for Fletcher of Tarnbank; the polar axis is of cast iron and the mounting very satisfactory and convenient, but unfortunately no detailed description has been published.
Fraunhofer's chef-d'oeuvre, the great Dorpat refractor, made for Otto Struve about 1820, had a mounting of this type, and was the first equatorial of any importance to be provided with clockwork.
The largest example of his work is the refractor of 24-in.
28, 1843) describes a " heliometre-oculaire " which he made for the great Pulkowa refractor, the result of consultations between himself and the elder Struve.
Refractor to enable it to take part in the International Photographic Survey of the Heavens.