Note 43 — Chapter VII · DESCRIPTION OF DIFFERENT STEREOSCOPES.
Reading edition
These solid telescopes may be made achromatic by cementing concave lenses of flint glass upon each end, or of crown glass if they are made of flint glass.
Reading edition
These solid telescopes may be made achromatic by cementing concave lenses of flint glass upon each end, or of crown glass if they are made of flint glass.