Eye chart smaller towards the bottom of the chart. The person removes any glasses or contact lenses, and stands or sits a standardized distance from the chart (e.g., 20 feet for the Snellen chart). The person is then asked to identify the optotypes on the chart, starting with large rows and continuing to smaller rows until the optotypes cannot be reliably identified any more. The row in which the person can reliably identify symbols defines the visual acuity. One eye is tested at a time. Practically, this is accomplished by covering the other eye with a hand, piece of paper, or a
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,