Gre′go-ri — an Tel′e-scope.
The first and most ordinary form of reflecting telescope, invented by Professor James Gregory of Scotland, and described by him 1663.Its object mirror or speculum is perforated in its axis, and reflects the image to a smaller concave speculum placed in the axis of the tube at a distance from the larger speculum. The image is viewed through an eye-piece in the aperture of the objectspeculum. See telescope.