The whole art of reflex dialling [electronic resource] : shewing the way to draw all manner of dialls which shall shew the hour by a spot of light reflected from a glasse upon any cieling, or other object whatsoever, without any respect had to the axis of the world, either projected or reflected. As also whether the glasse lie parallel to the horizon, or oblique unto it. Together with all necessary furniture belonging thereunto. All performed by an easie instrument fitted with lines to that purpose. By John Twysden, M.D.C.L.