...aberrations outside the axis, which cannot be compensated for in the objective. With these eye -pieces, particularly with that of 25 mm. focal length, the...principle on which the objectives have been constructed is mdicated in a paper by Prof. Abbe in this Journal. u On new methods for improving spherical correction,"...

...Professor Abbe and Dr. Schott have been working for the past five years to perfect. Of the ten lenses, two only are of siliceous glass, the other eight being...borates and phosphates. The crown and flint glass ordinarily used by opticians does not contain more than six chemical elements, while the new glass...

...Professor Abbe and Dr. Schott have been working for the past five years to perfect. Of the ten lenses, two only are of siliceous glass, the other eight being made of berates and phosphates. The crown and flint glass ordinarily used by opticians does not contain more...

...Professor Abbe and Dr. Schott have been working for the past five years to perfect. Of the ten lenses, two only are of siliceous glass, the other eight being made of berates and phosphates. The crown and flint glass ordinarily used by opticians does not contain more...

...aberrations outside the axis, which cannot be compensated for in the objective. With these eye -pieces, particularly with that of 25 mm. focal length, the...essential components) more than six chemical elements, 0, 0a, K, Na, Pb, and Si, whilst the new objective contains not less than fourteen elements. The optical...