- A telescope with a diagonal eyepiece, suspended vertically in gimbals because of the item end beneath a hard and fast diagonal jet mirror. It really is useful for delineating surroundings through an attached pencil.
- A telescope with a diagonal eyepiece, suspended vertically in gimbals by the item end beneath a fixed diagonal airplane mirror. It is employed for delineating landscapes, through a pencil at eye end which renders the delineation on paper.
- a kind of telescope built for the intended purpose of copying surroundings, etc.