Glass made without lead or iron, originally in a circular sheet. Formerly used in windows, it is now used as optical glass of low refractive index.
- ‘Based of the research, crown glass has a refractive index in the range of 1.5 to 1.6.’
- ‘Note that the magnifying power of the crown glass is twice that of the flint in this combination, yielding a net power about half that of the crown element alone.’
- ‘The ‘Barlow lens ‘, a modification of this telescope lens, is a negative achromatic combination of flint glass and crown glass.’’
- ‘Several panes of crown glass may be cut out of each disc.’
- ‘It retains many of its original Georgian features including sash windows, crown glass, ornate ceiling cornicing, dado rails and picture rails.’
- ‘Progress in the production of window glass from the hand craft of blowing crown glass to large sheets of drawn glass in 1915 had a very noticeable effect on the appearance of buildings.’
- ‘The discovery of achromatic lenses made of flint and crown glass heralded a new era for telescope makers, but the same did not apply to the microscope.’
- ‘The material's color approaches the water-white clarity of crown glass.’
- ‘The two most common kinds of glass used for making achromats are crown glass and flint glass.’
- ‘The other kind - called crown glass - was made by pouring molten glass out on a turntable and letting centrifigal forces spread it out from a central point.’
We take a look at several popular, though confusing, punctuation marks.