A noon-mark may easily be made by the aid of the transit instrument.
Surveyors make use of this proposition when they wish, without using a transit instrument, to run one line parallel to another.
The first plan is that of the "transit instrument," the second that of the "equatoreal."
The transit instrument was mounted as the transit circle is, between two solid stone piers, and moved in precisely the same way.
At that time, no original observations made at the transit instrument were ever preserved.
Hence the transit instrument and clock are the most important members of an astronomical observatory.
The transit instrument is a telescope which is fixed permanently in the meridian, and moves only in that plane.
The microscopic deviation of the axis of a transit instrument from the horizontal position.
transit instrument, with reversing arrangement, illumination with oil or electric lamp, Filar micrometer with two eye pieces.
The astronomical clock is the constant companion of the transit instrument.