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In many books in this series (especially older editions), a number of the plates are in black and white. For examples, older editions of the Eastern reptiles/amphibians book had many black and white plates which were colorized for the current edition, [1] and the original 1934 Eastern bird book had only 4 color plates. [2]
Intended for primary and secondary school level readers, the first books were field guides illustrated by James Gordon Irving, with such titles as Birds (1949), Insects (1951), and Mammals (1955). The series later expanded beyond identification guides to cover a wider range of subjects, such as Geology (1972), Scuba Diving (1968) , and Indian ...
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 floral diagram is a graphic representation of the structure of a flower. It shows the number of floral organs, their arrangement and fusion. Different parts of the flower are represented by their respective symbols. Floral diagrams are useful for flower identification or can help in understanding angiosperm evolution.
For a pixel pair (one white and one black pixel) this gives a pixel density of 128 pixels per degree (PPD). 6/6 vision is defined as the ability to resolve two points of light separated by a visual angle of one minute of arc, corresponding to 60 PPD, or about 290–350 pixels per inch for a display on a device held 250 to 300 mm from the eye.
Esme Glasses. These fashionable glasses from Warby Parker come in three different width options—narrow, medium, and wide—to ensure the best fit for any face shape and size.
An example of the Landolt C eye chart (also known as the Japanese eye chart). 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, while the ETDRS chart is designed for use at 4 meters. [16]
Some clinics do not have 6-metre eye lanes available, and either a half-size chart subtending the same angles at 3 metres (9.8 ft), or a reversed chart projected and viewed by a mirror is used to achieve the correct sized letters. In the most familiar acuity test, a Snellen chart is placed at a standard distance: 6 metres.