Eye chart number). The denominator indicates the distance in feet at which a person with normal vision could stand to correctly identify the same symbols identified by the person tested. For example, a visual acuity of 20/20 is considered normal. Numerous types of eye charts exist and are used in various situations. For example, the Snellen chart is designed for use at 6 meters or 20 feet, and is thus appropriate for testing distance vision. There is often also a need to test a subject's vision at near or occupational tasks (such as reading or computer use). For these situations, a Rosenbaum
Letter-Books of the City of London Letter-Books of the City of London The Letter-Books of the City of London are a series of fifty folio volumes in vellum containing entries of the matters of in which the City of London was interested or concerned, beginning in 1275 and concluding in 1509. The volumes are part of the collection of the City of London Records Office, and are kept in the London Metropolitan Archives. The volumes derive their name from being lettered from "A" to "Z" (with two odd volumes marked respectively "&c." and "AB") and again from "AA" to "ZZ". Besides being known by distinctive letters,