- bifocal spectacles
- 双焦点眼镜
Medical Chinese dictionary (湘雅医学词典). 2013.
bifocal spectacles
Look at other dictionaries:
bifocal lens — a lens with two principal focal lengths: the upper part of the lens gives a sharp image of distant objects and the lower part gives a sharp image of near objects, as when reading. Examples are bifocal spectacles, bifocal contact lenses, and… … Medical dictionary
bifocal lens — a lens with two principal focal lengths: the upper part of the lens gives a sharp image of distant objects and the lower part gives a sharp image of near objects, as when reading. Examples are bifocal spectacles, bifocal contact lenses, and… … The new mediacal dictionary
bifocal — adj. & n. adj. having two focuses, esp. of a lens with a part for distant vision and a part for near vision. n. (in pl.) bifocal spectacles … Useful english dictionary
spectacles — Lenses set in a frame that holds them in front of the eyes, used to correct errors of refraction or to protect the eyes. The parts of the s. are the lenses; the bridge between the lenses, resting on the nose; the rims or frames, encircling the… … Medical dictionary
bifocal — a. with two foci, especially applied to spectacle lens of which upper part is used for viewing distant and lower part for near objects; n. such lens; pl. spectacles with such lenses … Dictionary of difficult words
bifocals — bifocal spectacles, 1899, see BIFOCAL (Cf. bifocal). Conceived by Benjamin Franklin, but called by him double spectacles … Etymology dictionary
Franklin, Benjamin — born Jan. 17, 1706, Boston, Mass. died April 17, 1790, Philadelphia, Pa., U.S. American statesman, scientist, philosopher, and publisher. He was apprenticed at age 12 to his brother, a local printer. He taught himself to write effectively, and in … Universalium
1784 — Year 1784 (MDCCLXXXIV) was a leap year starting on Thursday (link will display the full calendar) of the Gregorian calendar (or a leap year starting on Monday of the 11 day slower Julian calendar). Events of 1784 January June * January 6 The… … Wikipedia
Dollond & Aitchison — Type formerly Limited, since 2009 subsidiary of Boots Opticians Industry Healthcare Founded 1750 … Wikipedia
Franklin,Benjamin — Franklin, Benjamin. 1706 1790. American public official, writer, scientist, and printer. After the success of his Poor Richard s Almanac (1732 1757), he entered politics and played a major part in the American Revolution. Franklin negotiated… … Universalium
Franklin , Benjamin — (1706–1790) American scientist, statesman, diplomat, printer, and inventor Franklin s father left England in 1682 and the following year settled in Boston, Massachusetts, where he worked as a candle maker and soap boiler. Although originally… … Scientists
