Search results
Results From The WOW.Com Content Network
Near visual acuity or near vision is a measure of how clearly a person can see nearby small objects or letters.Visual acuity in general usually refers clarity of distance vision, and is measured using eye charts like Snellen chart, LogMAR chart etc. Near vision is usually measured and recorded using a printed hand-held card containing different sized paragraphs, words, letters or symbols.
A fire hydrant marked as 3-inch. The inch (symbol: in or ″) is a unit of length in the British Imperial and the United States customary systems of measurement.It is equal to 1 / 36 yard or 1 / 12 of a foot.
A Snellen chart is an eye chart that can be used to measure visual acuity. Snellen charts are named after the Dutch ophthalmologist Herman Snellen who developed the chart in 1862 as a measurement tool for the acuity formula developed by his professor Franciscus Cornelius Donders .
Let the measure of the smallest main-scale reading, that is the distance between two consecutive graduations (also called its pitch) be S, and the distance between two consecutive vernier scale graduations be V, such that the length of (n − 1) main-scale divisions is equal to n vernier-scale divisions. Then
A bronze caliper, dating from 9 AD, was used for minute measurements during the Chinese Xin dynasty. The caliper had an inscription stating that it was "made on the gui-you day, [a] the first day [b] of the first month of the first year of Shijianguo. [c]" The calipers included a "slot and pin" and "graduated in inches and tenths of an inch ...
The Jaeger chart is an eye chart used in testing near visual acuity.It is a card on which paragraphs of text are printed, with the text sizes increasing from 0.37 mm to 2.5 mm. [1] This card is to be held by a patient at a fixed distance from the eye dependent on the J size being read.
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
The circular forms of wire gauge measurement devices are the most popular, and are generally 3 + 3 ⁄ 4 inches (95 mm) in diameter, with thirty-six notches; many have the decimal equivalents of the sizes stamped on the back. Oblong plates are similarly notched.