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Three spectacle lenses.

1900-1930
Segment polished on curved face to required reading curve. Ready for fusing. Stage in the manufacture of 'Kryptok' bi-focal spectacle lenses.

Segment polished on curved face to required reading curve

Fused blank ground and polished, giving the finished oval astigmatic bi-focal spectacle lens. Final stage in the manufacture of 'Kryptok' bi-focal spectacle lenses.

Fused blank ground and polished

Slab and segment fused by great heat and carefully annealed. Stage in the manufacture of 'Kryptok' bi-focal spectacle lenses.

Slab and segment fused by heat

Slab ground flat and shaped, with a reading curve depressed on one face. Ready for fusing stage in the manufacture of 'Kryptok' bi-focal spectacle lenses.

Slab ground flat and shaped

Selected segment of calculated high density, ground flat on one face and curved on the other. Stage in the manufacture of 'Kryptok' bi-focal spectacle lenses.

Selected segment of calculated high density

Selected unworked slab of calculated lower density, free from infections, stage in the manufacture of 'Kryptok' bi-focal spectacle lenses.

Selected unworked slab of calculated lower density

Number of spectacle lenses, circular, English, 1801-1920

Number of spectacle lenses

1801-1920
Twenty seven sunglass lenses, English, 1880-1940

Twenty seven sunglass lenses, English, 1880-1940

1880-1940
Collection of 24 tinted spectacle lenses, oval, glass, English, 1801-1920

Collection of 24 tinted spectacle lenses

1801-1920
Thirty five tinted spectacle lenses, English, 1851-1920

Thirty five tinted spectacle lenses

1851-1920
six stages in making fused tri-focal lenses (1) the segments are placed together, (2) segments fused together, and on to lens blank, (3) front surface of the compound lens is ground, (4) front surface of the compound lens polished, (5) lens cut to shape and bevelled, (6) plastic lenses mounted in spectacle frame. Supplied by Bateman, Frederick and Co (see note).

six stages in making fused tri-focal lenses (1) the segments are placed together