Herschell mount

[hes not well again]

I was reading a book from 1850 about building telescopes and ran across an illustration of a mount for a reflector scope designed and used by Caroline Herschel for her 16 inch. It seems to be an altazimuth mount. Basically it is a horizontal bearing with a board mounted on its edge. In the top corner a hole is bored through which the focuser is inserted and the vertical bearing is either on or near the focuser. Elevation is acheived by lifting or lowering the mirror end with rope. The advantage of this mount is that the ep is always at the same height and very steady. Has anyone any experience of this kind of mount or has it faded away into history?

[canuck]

Do you mean this one at the Science Museum in London?

[hes not well again]

No, the one I saw had the pivot actually at the focuser. The one in the science museum has it at the other end. The book is "on the construction of a silvered glass telescope" by Henry draper. Can be downloaded free at Open Library.org as a pdf file. Page 27

[hes not well again]

Further to that, the book says that the mount was used for a 27 inch newtonian belonging to Caroline and also by a Mr Naysmith [the celebrated engineer] used it for a "large" scope which he used to make drawings of the moon. The author describes it as a stationary eyepiece mount.