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Night blindness (nyctalopia)
| Морской словарь |
A sufferer from this vitamin deficiency disease has normal vision in adequate light, but gradually requires more and more time to adjust to diminishing illumination, and in semidarkness becomes unable to detect moving or contrasting objects that are clearly visible to others. hence the problem would not become evident until a night lookout failed to spot something important and, even then, the unfortunate sufferer was likely to be punished for inattention rather than given medical attention. when highly advanced the eyes become visibly ulcerated and the lids develop triangular silver-grey deposits known as bitot’s spots. the disease was as common as scurvy in sailing ship navies and far more pernicious because it has no noticeable symptoms in its early stages, only beginning to appear after about twenty-four months on an unvaried seafarer’s diet. the principal cause is deficiency of vitamin a and/or zinc, both of which are found in egg yolks, butter, cream, liver, and fish oil, while leafy green and yellow vegetables provide the pro-vitamin a carotene. none of these foodstuffs has a long storage life and could only be served for a short while after a ship set sail.
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Deficiency, английский
- Дефицит. отсутствие. нехватка. недостаток.
- См. defective feature
- Дефицит, недостача
- A lack of something necessary
- What is wanting of a ship`s cargo at the time of delivery.
- Недостаток, дефицит
- The amount by which a project`s cash flow is not adequate to meet debt service.
Diminishing, английский
Уменьшающийся; убывающий
Illumination, английский
- Освещение; облучение (цели)
- Lighting minus craft. also, someone else`s setup.
- The amount or intensity of light striking an object.
- The luminous flux density incident on a surface, i.e., the luminous flux per unit area; usually expressed in lumens per square foot or footcandles, and lumens per square meter or lux.
- Act of illuminating or state of being illuminated. see also illuminate. compare illuminance.2,6
Unfortunate, английский
Triangular, английский
Noticeable, английский
A заметный, явный (син. pronounced) accent
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Night glasses, английский
Binoculars with high light-gathering capability.
Nicholson tube, английский
An instrument formerly used to measure a ship’s speed by reading the inboard pressure in a tube whose end was outboard, underwater and facing forward. see also pitot tube.
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