The Cooke Triplet was introduced in 1895 by Dennis Taylor of Cooke and Sons. Originally, the two (exterior) Plano-convex lenses were composed of borosilicate crown glass, and the biconcave (center) lens was made of flint. This lens system was used in cameras and is still implemented in some cameras today. Note the long focal length to the image plane.
The view is 2D from the side. Try moving the light source and optical elements to see their effect on the system.