Grubb 'C' Patent Lenses has a 3" diameter glass. 'A' was 2" and they went up to 'G' (6"). There were smaller lenses for stereo use, Doublets (see below) and Petzvals. Later Grubb's were by Howard, Thomas's son and varied with many being Doublets. Still working on a history of Grubb lenses but its looking as though Thomas Grubb was the first maker to produce the Doublets which would become better known as Rapid Rectilinear lenses, in 1864 ..... tbc